diff --git a/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/IntroduceSecondaryIndexInsertDeleteRule.java b/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/IntroduceSecondaryIndexInsertDeleteRule.java
index 0969fd8..3fc178a 100644
--- a/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/IntroduceSecondaryIndexInsertDeleteRule.java
+++ b/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/IntroduceSecondaryIndexInsertDeleteRule.java
@@ -383,8 +383,8 @@
 
                     // Check the field type of the secondary key.
                     IAType secondaryKeyType;
-                    Pair<IAType, Boolean> keyPairType = Index.getNonNullableOpenFieldType(secondaryKeyTypes.get(0),
-                            secondaryKeyFields.get(0), recType);
+                    Pair<IAType, Boolean> keyPairType = Index.getNonNullableOpenFieldType(index,
+                            secondaryKeyTypes.get(0), secondaryKeyFields.get(0), recType);
                     secondaryKeyType = keyPairType.first;
 
                     List<Object> varTypes = new ArrayList<>();
@@ -526,8 +526,8 @@
                 }
             } else {
                 // Get type, dimensions and number of keys
-                Pair<IAType, Boolean> keyPairType =
-                        Index.getNonNullableOpenFieldType(secondaryKeyTypes.get(0), secondaryKeyFields.get(0), recType);
+                Pair<IAType, Boolean> keyPairType = Index.getNonNullableOpenFieldType(index, secondaryKeyTypes.get(0),
+                        secondaryKeyFields.get(0), recType);
                 IAType spatialType = keyPairType.first;
                 boolean isPointMBR =
                         spatialType.getTypeTag() == ATypeTag.POINT || spatialType.getTypeTag() == ATypeTag.POINT3D;
@@ -724,7 +724,7 @@
                         workingElement.getUnnestList(), workingElement.getProjectList().get(0));
                 List<Boolean> firstUnnestFlags = ArrayIndexUtil.getUnnestFlags(workingElement.getUnnestList(),
                         workingElement.getProjectList().get(0));
-                ArrayIndexUtil.walkArrayPath(recordType, flatFirstFieldName, firstUnnestFlags, branchCreator);
+                ArrayIndexUtil.walkArrayPath(index, recordType, flatFirstFieldName, firstUnnestFlags, branchCreator);
                 secondaryKeyVars.add(branchCreator.lastFieldVars.get(0));
 
                 // For all other elements in the PROJECT list, add an assign.
@@ -860,6 +860,14 @@
                     // Field not found --> This is either an open field or a nested field. it can't be accessed by index
                     theFieldAccessFunc =
                             getFieldAccessFunction(new MutableObject<>(varRef), pos, indexFieldId.fieldName);
+                    // check IndexUtil.castDefaultNull(index), too, because we always want to cast even if
+                    // the overriding type is the same as the overridden type (this is for the case where overriding
+                    // the type of closed field is allowed)
+                    // e.g. field "a" is a string in the dataset ds; CREATE INDEX .. ON ds(a:string) CAST (DEFAULT NULL)
+                    if (IndexUtil.castDefaultNull(index)) {
+                        theFieldAccessFunc = castConstructorFunction(indexFieldId.funId, indexFieldId.extraArg,
+                                theFieldAccessFunc, sourceLoc);
+                    }
                 }
                 vars.add(fieldVar);
                 exprs.add(new MutableObject<>(theFieldAccessFunc));
@@ -880,10 +888,19 @@
         IAType fieldType = sourceType.getSubFieldType(skName);
         FunctionIdentifier skFun = null;
         IAObject fmtArg = null;
+        Pair<FunctionIdentifier, IAObject> castExpr;
         if (fieldType == null) {
-            Pair<FunctionIdentifier, IAObject> castExpr = getCastExpression(index, skType, srcLoc);
+            // open field
+            castExpr = getCastExpression(index, skType, srcLoc);
             skFun = castExpr.first;
             fmtArg = castExpr.second;
+        } else {
+            // closed field
+            if (IndexUtil.castDefaultNull(index)) {
+                castExpr = IndexUtil.getTypeConstructorDefaultNull(index, skType, srcLoc);
+                skFun = castExpr.first;
+                fmtArg = castExpr.second;
+            }
         }
         return new IndexFieldId(skSrc, skName, skType.getTypeTag(), skFun, fmtArg);
     }
diff --git a/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/am/AccessMethodUtils.java b/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/am/AccessMethodUtils.java
index 67e3784..3e5d5ae 100644
--- a/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/am/AccessMethodUtils.java
+++ b/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/am/AccessMethodUtils.java
@@ -1223,8 +1223,8 @@
         if (idxType == IndexType.RTREE && (skFieldUsedAfterTopOp || requireVerificationAfterSIdxSearch)) {
             IOptimizableFuncExpr optFuncExpr = AccessMethodUtils.chooseFirstOptFuncExpr(secondaryIndex, analysisCtx);
             int optFieldIdx = AccessMethodUtils.chooseFirstOptFuncVar(secondaryIndex, analysisCtx);
-            Pair<IAType, Boolean> keyPairType = Index.getNonNullableOpenFieldType(optFuncExpr.getFieldType(optFieldIdx),
-                    optFuncExpr.getFieldName(optFieldIdx), recordType);
+            Pair<IAType, Boolean> keyPairType = Index.getNonNullableOpenFieldType(secondaryIndex,
+                    optFuncExpr.getFieldType(optFieldIdx), optFuncExpr.getFieldName(optFieldIdx), recordType);
             if (keyPairType == null) {
                 return null;
             }
@@ -2509,8 +2509,8 @@
         }
 
         int optFieldIdx = AccessMethodUtils.chooseFirstOptFuncVar(chosenIndex, analysisCtx);
-        Pair<IAType, Boolean> keyPairType = Index.getNonNullableOpenFieldType(optFuncExpr.getFieldType(optFieldIdx),
-                optFuncExpr.getFieldName(optFieldIdx), recordType);
+        Pair<IAType, Boolean> keyPairType = Index.getNonNullableOpenFieldType(chosenIndex,
+                optFuncExpr.getFieldType(optFieldIdx), optFuncExpr.getFieldName(optFieldIdx), recordType);
         if (keyPairType == null) {
             return false;
         }
@@ -3156,7 +3156,7 @@
                     List<String> flatName = ArrayIndexUtil.getFlattenedKeyFieldNames(e.getUnnestList(), project);
                     List<Boolean> unnestFlags = ArrayIndexUtil.getUnnestFlags(e.getUnnestList(), project);
                     analysisCtx.getArrayIndexStructureMatcher().reset(assignVar, subTree);
-                    ArrayIndexUtil.walkArrayPath(subTree.getRecordType(), flatName, unnestFlags,
+                    ArrayIndexUtil.walkArrayPath(index, subTree.getRecordType(), flatName, unnestFlags,
                             analysisCtx.getArrayIndexStructureMatcher());
 
                     LogicalVariable varAfterWalk = analysisCtx.getArrayIndexStructureMatcher().getEndVar();
diff --git a/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/am/RTreeAccessMethod.java b/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/am/RTreeAccessMethod.java
index 8d4b83a..971760a 100644
--- a/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/am/RTreeAccessMethod.java
+++ b/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/am/RTreeAccessMethod.java
@@ -130,8 +130,8 @@
         IOptimizableFuncExpr optFuncExpr = AccessMethodUtils.chooseFirstOptFuncExpr(chosenIndex, analysisCtx);
 
         int optFieldIdx = AccessMethodUtils.chooseFirstOptFuncVar(chosenIndex, analysisCtx);
-        Pair<IAType, Boolean> keyPairType = Index.getNonNullableOpenFieldType(optFuncExpr.getFieldType(optFieldIdx),
-                optFuncExpr.getFieldName(optFieldIdx), recordType);
+        Pair<IAType, Boolean> keyPairType = Index.getNonNullableOpenFieldType(chosenIndex,
+                optFuncExpr.getFieldType(optFieldIdx), optFuncExpr.getFieldName(optFieldIdx), recordType);
         if (keyPairType == null) {
             return false;
         }
@@ -234,7 +234,8 @@
         int optFieldIdx = AccessMethodUtils.chooseFirstOptFuncVar(chosenIndex, analysisCtx);
         IAType optFieldType = optFuncExpr.getFieldType(optFieldIdx);
         List<String> optFieldName = optFuncExpr.getFieldName(optFieldIdx);
-        Pair<IAType, Boolean> keyPairType = Index.getNonNullableOpenFieldType(optFieldType, optFieldName, recordType);
+        Pair<IAType, Boolean> keyPairType =
+                Index.getNonNullableOpenFieldType(chosenIndex, optFieldType, optFieldName, recordType);
         if (keyPairType == null) {
             return null;
         }
diff --git a/asterixdb/asterix-app/src/main/java/org/apache/asterix/app/translator/QueryTranslator.java b/asterixdb/asterix-app/src/main/java/org/apache/asterix/app/translator/QueryTranslator.java
index 00138ed..438397c 100644
--- a/asterixdb/asterix-app/src/main/java/org/apache/asterix/app/translator/QueryTranslator.java
+++ b/asterixdb/asterix-app/src/main/java/org/apache/asterix/app/translator/QueryTranslator.java
@@ -1214,17 +1214,20 @@
                     }
 
                     boolean isFieldFromSchema = projectTypePrime != null;
-                    if (isFieldFromSchema && stmtCreateIndex.hasCastDefaultNull()) {
-                        throw new CompilationException(ErrorCode.COMPILATION_ERROR, indexedElement.getSourceLocation(),
-                                "CAST is not allowed since field \"" + projectPath + "\" is typed");
-                    }
                     IAType fieldTypePrime;
                     boolean fieldTypeNullable, fieldTypeMissable;
                     if (projectTypeExpr == null) {
+                        // the type of the indexed field is NOT specified in the DDL
+                        if (stmtCreateIndex.hasCastDefaultNull()) {
+                            throw new CompilationException(ErrorCode.COMPILATION_ERROR,
+                                    stmtCreateIndex.getSourceLocation(),
+                                    "CAST modifier is used without specifying " + "the type of the indexed field");
+                        }
                         fieldTypePrime = projectTypePrime;
                         fieldTypeNullable = projectTypeNullable;
                         fieldTypeMissable = projectTypeMissable;
                     } else {
+                        // the type of the indexed field is explicitly specified in the DDL
                         if (stmtCreateIndex.isEnforced()) {
                             if (!projectTypeExpr.isUnknownable()) {
                                 throw new CompilationException(ErrorCode.INDEX_ILLEGAL_ENFORCED_NON_OPTIONAL,
@@ -1242,9 +1245,12 @@
                                         indexedElement.getSourceLocation(), indexType);
                             }
                             if (isFieldFromSchema) {
-                                throw new CompilationException(ErrorCode.COMPILATION_ERROR,
-                                        indexedElement.getSourceLocation(), "Typed index on \"" + projectPath
-                                                + "\" field could be created only for open datatype");
+                                // allow overriding the type of the closed-field only if CAST modifier is used
+                                if (!stmtCreateIndex.hasCastDefaultNull()) {
+                                    throw new CompilationException(ErrorCode.COMPILATION_ERROR,
+                                            indexedElement.getSourceLocation(), "Typed index on \"" + projectPath
+                                                    + "\" field could be created only for open datatype");
+                                }
                             }
                         }
 
@@ -1286,12 +1292,12 @@
             boolean castDefaultNullAllowed = indexType == IndexType.BTREE && !isSecondaryPrimary;
             if (stmtCreateIndex.hasCastDefaultNull() && !castDefaultNullAllowed) {
                 throw new CompilationException(ErrorCode.COMPILATION_ERROR, sourceLoc,
-                        "Cast Default Null is only allowed for B-Tree indexes");
+                        "CAST modifier is only allowed for B-Tree indexes");
             }
             if (stmtCreateIndex.getCastDefaultNull().getOrElse(false)) {
                 if (stmtCreateIndex.isEnforced()) {
                     throw new CompilationException(ErrorCode.COMPILATION_ERROR, sourceLoc,
-                            "Cast Default Null cannot be specified together with ENFORCED");
+                            "CAST modifier cannot be specified together with ENFORCED");
                 }
             }
             Index.IIndexDetails indexDetails;
diff --git a/asterixdb/asterix-app/src/test/java/org/apache/asterix/test/dataflow/TestLsmBTreeResourceFactoryProvider.java b/asterixdb/asterix-app/src/test/java/org/apache/asterix/test/dataflow/TestLsmBTreeResourceFactoryProvider.java
index 9818538..2ee8fcf 100644
--- a/asterixdb/asterix-app/src/test/java/org/apache/asterix/test/dataflow/TestLsmBTreeResourceFactoryProvider.java
+++ b/asterixdb/asterix-app/src/test/java/org/apache/asterix/test/dataflow/TestLsmBTreeResourceFactoryProvider.java
@@ -111,7 +111,7 @@
             } else {
                 sourceType = metaType;
             }
-            Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(
+            Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(index,
                     indexDetails.getKeyFieldTypes().get(i), indexDetails.getKeyFieldNames().get(i), sourceType);
             IAType keyType = keyTypePair.first;
             secondaryTypeTraits[i] = typeTraitProvider.getTypeTrait(keyType);
@@ -148,7 +148,7 @@
             } else {
                 sourceType = metaType;
             }
-            Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(
+            Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(index,
                     indexDetails.getKeyFieldTypes().get(i), indexDetails.getKeyFieldNames().get(i), sourceType);
             IAType keyType = keyTypePair.first;
             secondaryCmpFactories[i] = cmpFactoryProvider.getBinaryComparatorFactory(keyType, true);
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/queries/btree-index-selection/cast-default-null/cast-default-null-20.sqlpp b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/btree-index-selection/cast-default-null/cast-default-null-20.sqlpp
new file mode 100644
index 0000000..d0229a3
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/btree-index-selection/cast-default-null/cast-default-null-20.sqlpp
@@ -0,0 +1,36 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+DROP DATAVERSE test IF EXISTS;
+CREATE DATAVERSE test;
+USE test;
+
+CREATE TYPE t1 AS { id: int, s_f1: string, s_f2: string?, i_f: int? };
+CREATE DATASET ds7(t1) PRIMARY KEY id;
+
+CREATE INDEX idx1 ON ds7(s_f2);
+CREATE INDEX idx2 ON ds7(s_f2: string) CAST (DEFAULT NULL);
+CREATE INDEX idx3 ON ds7(s_f2: int) CAST (DEFAULT NULL);
+
+CREATE VIEW view7_1(id int, s_f2 string, i_f int) DEFAULT NULL AS SELECT id, s_f2, i_f FROM ds7;
+CREATE VIEW view7_2(id int, s_f2 int, i_f int) DEFAULT NULL AS SELECT id, s_f2, i_f FROM ds7;
+
+USE test;
+// index idx2 should be used
+SELECT id, s_f2 FROM view7_1 WHERE s_f2 < "4" ORDER BY id;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/queries/btree-index-selection/cast-default-null/cast-default-null-21.sqlpp b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/btree-index-selection/cast-default-null/cast-default-null-21.sqlpp
new file mode 100644
index 0000000..fcf95e6
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/btree-index-selection/cast-default-null/cast-default-null-21.sqlpp
@@ -0,0 +1,36 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+DROP DATAVERSE test IF EXISTS;
+CREATE DATAVERSE test;
+USE test;
+
+CREATE TYPE t1 AS { id: int, s_f1: string, s_f2: string?, i_f: int? };
+CREATE DATASET ds7(t1) PRIMARY KEY id;
+
+CREATE INDEX idx1 ON ds7(s_f2);
+CREATE INDEX idx2 ON ds7(s_f2: string) CAST (DEFAULT NULL);
+CREATE INDEX idx3 ON ds7(s_f2: int) CAST (DEFAULT NULL);
+
+CREATE VIEW view7_1(id int, s_f2 string, i_f int) DEFAULT NULL AS SELECT id, s_f2, i_f FROM ds7;
+CREATE VIEW view7_2(id int, s_f2 int, i_f int) DEFAULT NULL AS SELECT id, s_f2, i_f FROM ds7;
+
+USE test;
+// no index is used (and no result is returned because of incompatible types. s_f2 string vs. 4 int)
+SELECT id, s_f2 FROM view7_1 WHERE s_f2 < 4 ORDER BY id;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/queries/btree-index-selection/cast-default-null/cast-default-null-22.sqlpp b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/btree-index-selection/cast-default-null/cast-default-null-22.sqlpp
new file mode 100644
index 0000000..4e32cfb
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/btree-index-selection/cast-default-null/cast-default-null-22.sqlpp
@@ -0,0 +1,36 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+DROP DATAVERSE test IF EXISTS;
+CREATE DATAVERSE test;
+USE test;
+
+CREATE TYPE t1 AS { id: int, s_f1: string, s_f2: string?, i_f: int? };
+CREATE DATASET ds7(t1) PRIMARY KEY id;
+
+CREATE INDEX idx1 ON ds7(s_f2);
+CREATE INDEX idx2 ON ds7(s_f2: string) CAST (DEFAULT NULL);
+CREATE INDEX idx3 ON ds7(s_f2: int) CAST (DEFAULT NULL);
+
+CREATE VIEW view7_1(id int, s_f2 string, i_f int) DEFAULT NULL AS SELECT id, s_f2, i_f FROM ds7;
+CREATE VIEW view7_2(id int, s_f2 int, i_f int) DEFAULT NULL AS SELECT id, s_f2, i_f FROM ds7;
+
+USE test;
+// no index is used (and no result is returned because of incompatible types. s_f2 int vs. "4" string)
+SELECT id, s_f2 FROM view7_2 WHERE s_f2 < "4" ORDER BY id;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/queries/btree-index-selection/cast-default-null/cast-default-null-23.sqlpp b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/btree-index-selection/cast-default-null/cast-default-null-23.sqlpp
new file mode 100644
index 0000000..a9bd6ba
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/btree-index-selection/cast-default-null/cast-default-null-23.sqlpp
@@ -0,0 +1,36 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+DROP DATAVERSE test IF EXISTS;
+CREATE DATAVERSE test;
+USE test;
+
+CREATE TYPE t1 AS { id: int, s_f1: string, s_f2: string?, i_f: int? };
+CREATE DATASET ds7(t1) PRIMARY KEY id;
+
+CREATE INDEX idx1 ON ds7(s_f2);
+CREATE INDEX idx2 ON ds7(s_f2: string) CAST (DEFAULT NULL);
+CREATE INDEX idx3 ON ds7(s_f2: int) CAST (DEFAULT NULL);
+
+CREATE VIEW view7_1(id int, s_f2 string, i_f int) DEFAULT NULL AS SELECT id, s_f2, i_f FROM ds7;
+CREATE VIEW view7_2(id int, s_f2 int, i_f int) DEFAULT NULL AS SELECT id, s_f2, i_f FROM ds7;
+
+USE test;
+// index idx3 should be used
+SELECT id, s_f2 FROM view7_2 WHERE s_f2 < 4 ORDER BY id;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/queries/btree-index-selection/cast-default-null/cast-default-null-24.sqlpp b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/btree-index-selection/cast-default-null/cast-default-null-24.sqlpp
new file mode 100644
index 0000000..ba2c8ff
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/btree-index-selection/cast-default-null/cast-default-null-24.sqlpp
@@ -0,0 +1,37 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+DROP DATAVERSE test IF EXISTS;
+CREATE DATAVERSE test;
+USE test;
+
+CREATE TYPE t1 AS { id: int, s_f1: string, s_f2: string?, i_f: int? };
+CREATE DATASET ds7(t1) PRIMARY KEY id;
+
+CREATE INDEX idx1 ON ds7(s_f2);
+CREATE INDEX idx2 ON ds7(s_f2: string) CAST (DEFAULT NULL);
+CREATE INDEX idx3 ON ds7(s_f2: int) CAST (DEFAULT NULL);
+
+CREATE VIEW view7_1(id int, s_f2 string, i_f int) DEFAULT NULL AS SELECT id, s_f2, i_f FROM ds7;
+CREATE VIEW view7_2(id int, s_f2 int, i_f int) DEFAULT NULL AS SELECT id, s_f2, i_f FROM ds7;
+
+USE test;
+// index idx1 should be used
+set `compiler.indexonly` "false"; // there is an issue with using index only plan where nulls/missings are included
+SELECT id, s_f2 FROM ds7 WHERE s_f2 < "4" ORDER BY id;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/results/btree-index-selection/cast-default-null/cast-default-null-20.plan b/asterixdb/asterix-app/src/test/resources/optimizerts/results/btree-index-selection/cast-default-null/cast-default-null-20.plan
new file mode 100644
index 0000000..885b6ba
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/results/btree-index-selection/cast-default-null/cast-default-null-20.plan
@@ -0,0 +1,23 @@
+-- DISTRIBUTE_RESULT  |PARTITIONED|
+  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+    -- STREAM_PROJECT  |PARTITIONED|
+      -- ASSIGN  |PARTITIONED|
+        -- SORT_MERGE_EXCHANGE [$$65(ASC) ]  |PARTITIONED|
+          -- STABLE_SORT [$$65(ASC)]  |PARTITIONED|
+            -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+              -- STREAM_PROJECT  |PARTITIONED|
+                -- ASSIGN  |PARTITIONED|
+                  -- STREAM_SELECT  |PARTITIONED|
+                    -- STREAM_PROJECT  |PARTITIONED|
+                      -- ASSIGN  |PARTITIONED|
+                        -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                          -- BTREE_SEARCH (test.ds7.ds7)  |PARTITIONED|
+                            -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                              -- STABLE_SORT [$$70(ASC)]  |PARTITIONED|
+                                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                  -- STREAM_PROJECT  |PARTITIONED|
+                                    -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                      -- BTREE_SEARCH (test.ds7.idx2)  |PARTITIONED|
+                                        -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                          -- ASSIGN  |PARTITIONED|
+                                            -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/results/btree-index-selection/cast-default-null/cast-default-null-21.plan b/asterixdb/asterix-app/src/test/resources/optimizerts/results/btree-index-selection/cast-default-null/cast-default-null-21.plan
new file mode 100644
index 0000000..a560c7f
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/results/btree-index-selection/cast-default-null/cast-default-null-21.plan
@@ -0,0 +1,16 @@
+-- DISTRIBUTE_RESULT  |PARTITIONED|
+  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+    -- STREAM_PROJECT  |PARTITIONED|
+      -- ASSIGN  |PARTITIONED|
+        -- SORT_MERGE_EXCHANGE [$$65(ASC) ]  |PARTITIONED|
+          -- STABLE_SORT [$$65(ASC)]  |PARTITIONED|
+            -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+              -- STREAM_PROJECT  |PARTITIONED|
+                -- ASSIGN  |PARTITIONED|
+                  -- STREAM_SELECT  |PARTITIONED|
+                    -- STREAM_PROJECT  |PARTITIONED|
+                      -- ASSIGN  |PARTITIONED|
+                        -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                          -- DATASOURCE_SCAN (test.ds7)  |PARTITIONED|
+                            -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                              -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/results/btree-index-selection/cast-default-null/cast-default-null-22.plan b/asterixdb/asterix-app/src/test/resources/optimizerts/results/btree-index-selection/cast-default-null/cast-default-null-22.plan
new file mode 100644
index 0000000..a560c7f
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/results/btree-index-selection/cast-default-null/cast-default-null-22.plan
@@ -0,0 +1,16 @@
+-- DISTRIBUTE_RESULT  |PARTITIONED|
+  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+    -- STREAM_PROJECT  |PARTITIONED|
+      -- ASSIGN  |PARTITIONED|
+        -- SORT_MERGE_EXCHANGE [$$65(ASC) ]  |PARTITIONED|
+          -- STABLE_SORT [$$65(ASC)]  |PARTITIONED|
+            -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+              -- STREAM_PROJECT  |PARTITIONED|
+                -- ASSIGN  |PARTITIONED|
+                  -- STREAM_SELECT  |PARTITIONED|
+                    -- STREAM_PROJECT  |PARTITIONED|
+                      -- ASSIGN  |PARTITIONED|
+                        -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                          -- DATASOURCE_SCAN (test.ds7)  |PARTITIONED|
+                            -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                              -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/results/btree-index-selection/cast-default-null/cast-default-null-23.plan b/asterixdb/asterix-app/src/test/resources/optimizerts/results/btree-index-selection/cast-default-null/cast-default-null-23.plan
new file mode 100644
index 0000000..88537b6
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/results/btree-index-selection/cast-default-null/cast-default-null-23.plan
@@ -0,0 +1,23 @@
+-- DISTRIBUTE_RESULT  |PARTITIONED|
+  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+    -- STREAM_PROJECT  |PARTITIONED|
+      -- ASSIGN  |PARTITIONED|
+        -- SORT_MERGE_EXCHANGE [$$65(ASC) ]  |PARTITIONED|
+          -- STABLE_SORT [$$65(ASC)]  |PARTITIONED|
+            -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+              -- STREAM_PROJECT  |PARTITIONED|
+                -- ASSIGN  |PARTITIONED|
+                  -- STREAM_SELECT  |PARTITIONED|
+                    -- STREAM_PROJECT  |PARTITIONED|
+                      -- ASSIGN  |PARTITIONED|
+                        -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                          -- BTREE_SEARCH (test.ds7.ds7)  |PARTITIONED|
+                            -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                              -- STABLE_SORT [$$70(ASC)]  |PARTITIONED|
+                                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                  -- STREAM_PROJECT  |PARTITIONED|
+                                    -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                      -- BTREE_SEARCH (test.ds7.idx3)  |PARTITIONED|
+                                        -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                          -- ASSIGN  |PARTITIONED|
+                                            -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/results/btree-index-selection/cast-default-null/cast-default-null-24.plan b/asterixdb/asterix-app/src/test/resources/optimizerts/results/btree-index-selection/cast-default-null/cast-default-null-24.plan
new file mode 100644
index 0000000..85d3144
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/results/btree-index-selection/cast-default-null/cast-default-null-24.plan
@@ -0,0 +1,19 @@
+-- DISTRIBUTE_RESULT  |PARTITIONED|
+  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+    -- STREAM_PROJECT  |PARTITIONED|
+      -- ASSIGN  |PARTITIONED|
+        -- SORT_MERGE_EXCHANGE [$$20(ASC) ]  |PARTITIONED|
+          -- STREAM_SELECT  |PARTITIONED|
+            -- STREAM_PROJECT  |PARTITIONED|
+              -- ASSIGN  |PARTITIONED|
+                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                  -- BTREE_SEARCH (test.ds7.ds7)  |PARTITIONED|
+                    -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                      -- STABLE_SORT [$$25(ASC)]  |PARTITIONED|
+                        -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                          -- STREAM_PROJECT  |PARTITIONED|
+                            -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                              -- BTREE_SEARCH (test.ds7.idx1)  |PARTITIONED|
+                                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                  -- ASSIGN  |PARTITIONED|
+                                    -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null-negative/index-cast-null-negative.003.ddl.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null-negative/index-cast-null-negative.003.ddl.sqlpp
index 3a4bf6a..ce5bf39 100644
--- a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null-negative/index-cast-null-negative.003.ddl.sqlpp
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null-negative/index-cast-null-negative.003.ddl.sqlpp
@@ -17,5 +17,5 @@
  * under the License.
  */
 USE test;
-// cannot use CAST with a typed field
+// the target type of the CAST is not specified
 CREATE INDEX idx ON ds1(typed_f1) CAST (DEFAULT NULL);
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null-negative/index-cast-null-negative.004.ddl.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null-negative/index-cast-null-negative.004.ddl.sqlpp
index c1cfa20..dc14260 100644
--- a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null-negative/index-cast-null-negative.004.ddl.sqlpp
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null-negative/index-cast-null-negative.004.ddl.sqlpp
@@ -17,5 +17,5 @@
  * under the License.
  */
 USE test;
-// cannot use CAST with a typed field
-CREATE INDEX idx ON ds1(typed_f2: int) CAST (DEFAULT NULL);
\ No newline at end of file
+// cannot override the type of a closed field without using CAST
+CREATE INDEX idx ON ds1(typed_f2: int);
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.000.ddl.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.000.ddl.sqlpp
index 3178a11..e015377 100644
--- a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.000.ddl.sqlpp
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.000.ddl.sqlpp
@@ -24,16 +24,15 @@
 CREATE DATAVERSE test;
 USE test;
 CREATE TYPE t1 AS { id: int, s_f: string, d_f: double, i_f: int, b_f: boolean };
+CREATE TYPE t2 AS { id: int, s_f1: string, s_f2: string?, i_f: int? };
 CREATE DATASET ds1(t1) PRIMARY KEY id;
 CREATE DATASET ds2(t1) PRIMARY KEY id;
 CREATE DATASET ds3(id int not unknown) OPEN TYPE PRIMARY KEY id;
 CREATE DATASET ds4(id int not unknown) OPEN TYPE PRIMARY KEY id;
-
-//CREATE INDEX ds2_idx1 ON ds2(s_f: int) CAST (DEFAULT NULL);
+CREATE DATASET ds5(t2) PRIMARY KEY id;
 
 CREATE INDEX ds2_o_idx1 ON ds2(o_s_f: int, o_i_f: string) INCLUDE UNKNOWN KEY CAST (DEFAULT NULL);
 CREATE INDEX ds2_o_idx2 ON ds2(o_s_f: double, o_d_f: string) CAST (DEFAULT NULL);
-//CREATE INDEX ds2_o_idx3 ON ds2(o_s_f: boolean, o_b_f: string) CAST (DEFAULT NULL);
 
 CREATE INDEX ds2_o_idx4 ON ds2(a.s_f: int) CAST (DEFAULT NULL);
 
@@ -51,4 +50,18 @@
 CREATE INDEX ds3_o_idx_f_d_fmt ON ds3(f_d_fmt: date) CAST (DEFAULT NULL date 'MM/DD/YYYY');
 CREATE INDEX ds3_o_idx_f_t_fmt ON ds3(f_t_fmt: time) CAST (DEFAULT NULL time 'hh:mm:ss.nnna');
 
-CREATE INDEX ds3_o_idx_invalid_fmt ON ds3(f_d_fmt: date) CAST (DEFAULT NULL date 'invalid_format');
\ No newline at end of file
+CREATE INDEX ds3_o_idx_invalid_fmt ON ds3(f_d_fmt: date) CAST (DEFAULT NULL date 'invalid_format');
+
+// on closed fields
+CREATE INDEX idx1 ON ds5(s_f1);
+CREATE INDEX idx2 ON ds5(s_f1: string) CAST (DEFAULT NULL);
+CREATE INDEX idx3 ON ds5(s_f1: int) CAST (DEFAULT NULL);
+
+CREATE INDEX idx4 ON ds5(s_f2);
+CREATE INDEX idx5 ON ds5(s_f2: string) CAST (DEFAULT NULL);
+CREATE INDEX idx6 ON ds5(s_f2: int) CAST (DEFAULT NULL);
+
+CREATE INDEX idx7 ON ds5(i_f: int) CAST (DEFAULT NULL);
+CREATE INDEX idx8 ON ds5(i_f: string) CAST (DEFAULT NULL);
+
+CREATE INDEX idx_exc1 ON ds5(s_f2: int) EXCLUDE UNKNOWN KEY CAST (DEFAULT NULL);
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.001.update.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.001.update.sqlpp
index 969f727..fac0b31 100644
--- a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.001.update.sqlpp
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.001.update.sqlpp
@@ -60,4 +60,13 @@
 {"id": 4, 'f_dt':'2019-01-20T14:40:41.001', 'f_d':'2019-01-20', 'f_t':'14:40:41.001', 'f_dt_fmt':'01/20/2019 02:40:41.001pm', 'f_d_fmt':'01/20/2019', 'f_t_fmt':'02:40:41.001pm'},
 {"id": 5, 'f_dt':null, 'f_d':null, 'f_t':null, 'f_dt_fmt':null, 'f_d_fmt':null, 'f_t_fmt':null},
 {"id": 6}
+];
+
+INSERT INTO ds5 [
+{"id": 1, "s_f1": "s",   "s_f2": "s",   "i_f": 1 },
+{"id": 2, "s_f1": "2",   "s_f2": "2",   "i_f": 2 },
+{"id": 3, "s_f1": "3.5", "s_f2": "3.5", "i_f": 3 },
+{"id": 4, "s_f1": "4",   "s_f2": "4",   "i_f": 4 },
+{"id": 5, "s_f1": "5",   "s_f2": null,   "i_f": null },
+{"id": 6, "s_f1": "" }
 ];
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.002.ddl.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.002.ddl.sqlpp
index ee2c025..8ddbebc 100644
--- a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.002.ddl.sqlpp
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.002.ddl.sqlpp
@@ -22,11 +22,8 @@
 
 USE test;
 
-//CREATE INDEX ds1_idx1 ON ds1(s_f: int) CAST(DEFAULT NULL);
-
 CREATE INDEX ds1_o_idx1 ON ds1(o_s_f: int, o_i_f: string) INCLUDE UNKNOWN KEY CAST(DEFAULT NULL);
 CREATE INDEX ds1_o_idx2 ON ds1(o_s_f: double, o_d_f: string) CAST(DEFAULT NULL);
-//CREATE INDEX ds1_o_idx3 ON ds1(o_s_f: boolean, o_b_f: string) CAST(DEFAULT NULL);
 
 CREATE INDEX ds1_o_idx4 ON ds1(a.s_f: int) CAST(DEFAULT NULL);
 
@@ -44,4 +41,18 @@
 CREATE INDEX ds4_o_idx_f_d_fmt ON ds4(f_d_fmt: date) CAST (DEFAULT NULL date 'MM/DD/YYYY');
 CREATE INDEX ds4_o_idx_f_t_fmt ON ds4(f_t_fmt: time) CAST (DEFAULT NULL time 'hh:mm:ss.nnna');
 
-CREATE INDEX ds4_o_idx_invalid_fmt ON ds4(f_d_fmt: date) CAST (DEFAULT NULL date 'invalid_format');
\ No newline at end of file
+CREATE INDEX ds4_o_idx_invalid_fmt ON ds4(f_d_fmt: date) CAST (DEFAULT NULL date 'invalid_format');
+
+// on closed fields
+CREATE INDEX idx9 ON ds5(s_f1);
+CREATE INDEX idx10 ON ds5(s_f1: string) CAST (DEFAULT NULL);
+CREATE INDEX idx11 ON ds5(s_f1: int) CAST (DEFAULT NULL);
+
+CREATE INDEX idx12 ON ds5(s_f2);
+CREATE INDEX idx13 ON ds5(s_f2: string) CAST (DEFAULT NULL);
+CREATE INDEX idx14 ON ds5(s_f2: int) CAST (DEFAULT NULL);
+
+CREATE INDEX idx15 ON ds5(i_f: int) CAST (DEFAULT NULL);
+CREATE INDEX idx16 ON ds5(i_f: string) CAST (DEFAULT NULL);
+
+CREATE INDEX idx_exc2 ON ds5(s_f2: int) EXCLUDE UNKNOWN KEY CAST (DEFAULT NULL);
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.032.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.032.query.sqlpp
new file mode 100644
index 0000000..13b56e6
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.032.query.sqlpp
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+
+SET `import-private-functions` `true`;
+FROM DUMP_INDEX("test", "ds5", "idx1") AS v
+SELECT VALUE v
+ORDER BY v.values;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.033.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.033.query.sqlpp
new file mode 100644
index 0000000..4e3ea15
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.033.query.sqlpp
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+
+SET `import-private-functions` `true`;
+FROM DUMP_INDEX("test", "ds5", "idx2") AS v
+SELECT VALUE v
+ORDER BY v.values;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.034.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.034.query.sqlpp
new file mode 100644
index 0000000..43bd912
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.034.query.sqlpp
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+
+SET `import-private-functions` `true`;
+FROM DUMP_INDEX("test", "ds5", "idx3") AS v
+SELECT VALUE v
+ORDER BY v.values;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.035.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.035.query.sqlpp
new file mode 100644
index 0000000..3129e17
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.035.query.sqlpp
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+
+SET `import-private-functions` `true`;
+FROM DUMP_INDEX("test", "ds5", "idx4") AS v
+SELECT VALUE v
+ORDER BY v.values;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.036.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.036.query.sqlpp
new file mode 100644
index 0000000..7dac7ba
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.036.query.sqlpp
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+
+SET `import-private-functions` `true`;
+FROM DUMP_INDEX("test", "ds5", "idx5") AS v
+SELECT VALUE v
+ORDER BY v.values;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.037.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.037.query.sqlpp
new file mode 100644
index 0000000..442e4c8
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.037.query.sqlpp
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+
+SET `import-private-functions` `true`;
+FROM DUMP_INDEX("test", "ds5", "idx6") AS v
+SELECT VALUE v
+ORDER BY v.values;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.038.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.038.query.sqlpp
new file mode 100644
index 0000000..0e16524
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.038.query.sqlpp
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+
+SET `import-private-functions` `true`;
+FROM DUMP_INDEX("test", "ds5", "idx7") AS v
+SELECT VALUE v
+ORDER BY v.values;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.039.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.039.query.sqlpp
new file mode 100644
index 0000000..73bcd31
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.039.query.sqlpp
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+
+SET `import-private-functions` `true`;
+FROM DUMP_INDEX("test", "ds5", "idx8") AS v
+SELECT VALUE v
+ORDER BY v.values;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.040.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.040.query.sqlpp
new file mode 100644
index 0000000..b8683cd
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.040.query.sqlpp
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+
+SET `import-private-functions` `true`;
+FROM DUMP_INDEX("test", "ds5", "idx9") AS v
+SELECT VALUE v
+ORDER BY v.values;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.041.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.041.query.sqlpp
new file mode 100644
index 0000000..a694667
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.041.query.sqlpp
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+
+SET `import-private-functions` `true`;
+FROM DUMP_INDEX("test", "ds5", "idx10") AS v
+SELECT VALUE v
+ORDER BY v.values;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.042.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.042.query.sqlpp
new file mode 100644
index 0000000..ba593c5
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.042.query.sqlpp
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+
+SET `import-private-functions` `true`;
+FROM DUMP_INDEX("test", "ds5", "idx11") AS v
+SELECT VALUE v
+ORDER BY v.values;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.043.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.043.query.sqlpp
new file mode 100644
index 0000000..c5931ab
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.043.query.sqlpp
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+
+SET `import-private-functions` `true`;
+FROM DUMP_INDEX("test", "ds5", "idx12") AS v
+SELECT VALUE v
+ORDER BY v.values;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.044.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.044.query.sqlpp
new file mode 100644
index 0000000..d168fb3
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.044.query.sqlpp
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+
+SET `import-private-functions` `true`;
+FROM DUMP_INDEX("test", "ds5", "idx13") AS v
+SELECT VALUE v
+ORDER BY v.values;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.045.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.045.query.sqlpp
new file mode 100644
index 0000000..090b384
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.045.query.sqlpp
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+
+SET `import-private-functions` `true`;
+FROM DUMP_INDEX("test", "ds5", "idx14") AS v
+SELECT VALUE v
+ORDER BY v.values;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.046.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.046.query.sqlpp
new file mode 100644
index 0000000..1d66487
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.046.query.sqlpp
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+
+SET `import-private-functions` `true`;
+FROM DUMP_INDEX("test", "ds5", "idx15") AS v
+SELECT VALUE v
+ORDER BY v.values;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.047.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.047.query.sqlpp
new file mode 100644
index 0000000..b6455d1
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.047.query.sqlpp
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+
+SET `import-private-functions` `true`;
+FROM DUMP_INDEX("test", "ds5", "idx16") AS v
+SELECT VALUE v
+ORDER BY v.values;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.048.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.048.query.sqlpp
new file mode 100644
index 0000000..e551576
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.048.query.sqlpp
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+
+SET `import-private-functions` `true`;
+FROM DUMP_INDEX("test", "ds5", "idx_exc1") AS v
+SELECT VALUE v
+ORDER BY v.values;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.049.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.049.query.sqlpp
new file mode 100644
index 0000000..6046ab4
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.049.query.sqlpp
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+
+SET `import-private-functions` `true`;
+FROM DUMP_INDEX("test", "ds5", "idx_exc2") AS v
+SELECT VALUE v
+ORDER BY v.values;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.050.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.050.query.sqlpp
new file mode 100644
index 0000000..cc547f8
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/ddl/index-cast-null/index-cast-null.050.query.sqlpp
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+
+FROM Metadata.`Index` v
+WHERE v.DatasetName = 'ds5' AND v.IsPrimary = false
+SELECT v.IndexName, v.SearchKey, v.SearchKeyType, v.`Cast`
+ORDER BY v.IndexName;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.01.ddl.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.01.ddl.sqlpp
index 98e54e3..9cc8fdd 100644
--- a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.01.ddl.sqlpp
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.01.ddl.sqlpp
@@ -21,12 +21,15 @@
 CREATE DATAVERSE test;
 USE test;
 
+CREATE TYPE t1 AS { id: int, s_f1: string, s_f2: string?, i_f: int? };
+
 CREATE DATASET ds1(id int not unknown, a string, b int) OPEN TYPE PRIMARY KEY id;
 CREATE DATASET ds2(id int not unknown, a string, b int) OPEN TYPE PRIMARY KEY id;
 CREATE DATASET ds3(id int not unknown, a string, b int) OPEN TYPE PRIMARY KEY id;
 CREATE DATASET ds4(id int not unknown, a string, b int) OPEN TYPE PRIMARY KEY id;
 CREATE DATASET ds5(id int not unknown) OPEN TYPE PRIMARY KEY id;
 CREATE DATASET ds6(id int not unknown) OPEN TYPE PRIMARY KEY id;
+CREATE DATASET ds7(t1) PRIMARY KEY id;
 
 CREATE INDEX idx1 ON ds1(x: int);
 CREATE INDEX idx2 ON ds2(x: int) CAST (DEFAULT NULL);
@@ -40,6 +43,10 @@
 CREATE INDEX idx6_d ON ds6(f_d: date) CAST (DEFAULT NULL);
 CREATE INDEX idx6_t ON ds6(f_t: time) CAST (DEFAULT NULL);
 
+CREATE INDEX idx1 ON ds7(s_f2);
+CREATE INDEX idx2 ON ds7(s_f2: string) CAST (DEFAULT NULL);
+CREATE INDEX idx3 ON ds7(s_f2: int) CAST (DEFAULT NULL);
+
 CREATE VIEW view1(id int, x int, y int) DEFAULT NULL AS SELECT id, x, y FROM ds1;
 CREATE VIEW view2(id int, x int, y int) DEFAULT NULL AS SELECT id, x, y FROM ds2;
 CREATE VIEW view3(id int, x string, y int) DEFAULT NULL AS SELECT id, x, y FROM ds3;
@@ -56,4 +63,7 @@
 
 CREATE VIEW view6_dt(id int, f_dt datetime) DEFAULT NULL AS SELECT id, f_dt FROM ds6;
 CREATE VIEW view6_d(id int, f_d date) DEFAULT NULL AS SELECT id, f_d FROM ds6;
-CREATE VIEW view6_t(id int, f_t time) DEFAULT NULL AS SELECT id, f_t FROM ds6;
\ No newline at end of file
+CREATE VIEW view6_t(id int, f_t time) DEFAULT NULL AS SELECT id, f_t FROM ds6;
+
+CREATE VIEW view7_1(id int, s_f2 string, i_f int) DEFAULT NULL AS SELECT id, s_f2, i_f FROM ds7;
+CREATE VIEW view7_2(id int, s_f2 int, i_f int) DEFAULT NULL AS SELECT id, s_f2, i_f FROM ds7;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.02.update.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.02.update.sqlpp
index a7d6ba6..1a51639 100644
--- a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.02.update.sqlpp
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.02.update.sqlpp
@@ -73,4 +73,13 @@
 {"id": 4, 'f_dt':'2019-01-20T14:40:41.001', 'f_d':'2019-01-20', 'f_t':'14:40:41.001'},
 {"id": 5, 'f_dt':null, 'f_d':null, 'f_t':null},
 {"id": 6}
+];
+
+INSERT INTO ds7 [
+{"id": 1, "s_f1": "s",   "s_f2": "s",   "i_f": 1 },
+{"id": 2, "s_f1": "2",   "s_f2": "2",   "i_f": 2 },
+{"id": 3, "s_f1": "3.5", "s_f2": "3.5", "i_f": 3 },
+{"id": 4, "s_f1": "4",   "s_f2": "4",   "i_f": 4 },
+{"id": 5, "s_f1": "5",   "s_f2": null,   "i_f": null },
+{"id": 6, "s_f1": "" }
 ];
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.19.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.19.query.sqlpp
new file mode 100644
index 0000000..e632e91
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.19.query.sqlpp
@@ -0,0 +1,22 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+// index idx2 should be used
+SELECT id, s_f2 FROM view7_1 WHERE s_f2 < "4" ORDER BY id;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.20.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.20.query.sqlpp
new file mode 100644
index 0000000..56296e8
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.20.query.sqlpp
@@ -0,0 +1,22 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+// no index is used (and no result is returned because of incompatible types. s_f2 string vs. 4 int)
+SELECT id, s_f2 FROM view7_1 WHERE s_f2 < 4 ORDER BY id;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.21.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.21.query.sqlpp
new file mode 100644
index 0000000..7e03ebf
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.21.query.sqlpp
@@ -0,0 +1,22 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+// no index is used (and no result is returned because of incompatible types. s_f2 int vs. "4" string)
+SELECT id, s_f2 FROM view7_2 WHERE s_f2 < "4" ORDER BY id;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.22.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.22.query.sqlpp
new file mode 100644
index 0000000..f0eece2
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.22.query.sqlpp
@@ -0,0 +1,22 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+// index idx3 should be used
+SELECT id, s_f2 FROM view7_2 WHERE s_f2 < 4 ORDER BY id;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.23.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.23.query.sqlpp
new file mode 100644
index 0000000..4fe0cae
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/index-selection/cast-default-null/cast-default-null.23.query.sqlpp
@@ -0,0 +1,23 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+USE test;
+// index idx1 should be used
+set `compiler.indexonly` "false"; // there is an issue with using index only plan where nulls/missings are included
+SELECT id, s_f2 FROM ds7 WHERE s_f2 < "4" ORDER BY id;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.032.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.032.adm
new file mode 100644
index 0000000..64cd5cf
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.032.adm
@@ -0,0 +1,6 @@
+{ "values": [ "", 6 ] }
+{ "values": [ "2", 2 ] }
+{ "values": [ "3.5", 3 ] }
+{ "values": [ "4", 4 ] }
+{ "values": [ "5", 5 ] }
+{ "values": [ "s", 1 ] }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.033.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.033.adm
new file mode 100644
index 0000000..64cd5cf
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.033.adm
@@ -0,0 +1,6 @@
+{ "values": [ "", 6 ] }
+{ "values": [ "2", 2 ] }
+{ "values": [ "3.5", 3 ] }
+{ "values": [ "4", 4 ] }
+{ "values": [ "5", 5 ] }
+{ "values": [ "s", 1 ] }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.034.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.034.adm
new file mode 100644
index 0000000..1674d82
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.034.adm
@@ -0,0 +1,6 @@
+{ "values": [ null, 1 ] }
+{ "values": [ 0, 6 ] }
+{ "values": [ 2, 2 ] }
+{ "values": [ 3, 3 ] }
+{ "values": [ 4, 4 ] }
+{ "values": [ 5, 5 ] }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.035.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.035.adm
new file mode 100644
index 0000000..97e4e83
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.035.adm
@@ -0,0 +1,6 @@
+{ "values": [ null, 5 ] }
+{ "values": [ 6 ] }
+{ "values": [ "2", 2 ] }
+{ "values": [ "3.5", 3 ] }
+{ "values": [ "4", 4 ] }
+{ "values": [ "s", 1 ] }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.036.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.036.adm
new file mode 100644
index 0000000..feca349
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.036.adm
@@ -0,0 +1,6 @@
+{ "values": [ null, 5 ] }
+{ "values": [ null, 6 ] }
+{ "values": [ "2", 2 ] }
+{ "values": [ "3.5", 3 ] }
+{ "values": [ "4", 4 ] }
+{ "values": [ "s", 1 ] }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.037.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.037.adm
new file mode 100644
index 0000000..8d8fe2a
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.037.adm
@@ -0,0 +1,6 @@
+{ "values": [ null, 1 ] }
+{ "values": [ null, 5 ] }
+{ "values": [ null, 6 ] }
+{ "values": [ 2, 2 ] }
+{ "values": [ 3, 3 ] }
+{ "values": [ 4, 4 ] }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.038.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.038.adm
new file mode 100644
index 0000000..f03683f
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.038.adm
@@ -0,0 +1,6 @@
+{ "values": [ null, 5 ] }
+{ "values": [ null, 6 ] }
+{ "values": [ 1, 1 ] }
+{ "values": [ 2, 2 ] }
+{ "values": [ 3, 3 ] }
+{ "values": [ 4, 4 ] }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.039.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.039.adm
new file mode 100644
index 0000000..12f73b1
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.039.adm
@@ -0,0 +1,6 @@
+{ "values": [ null, 5 ] }
+{ "values": [ null, 6 ] }
+{ "values": [ "1", 1 ] }
+{ "values": [ "2", 2 ] }
+{ "values": [ "3", 3 ] }
+{ "values": [ "4", 4 ] }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.040.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.040.adm
new file mode 100644
index 0000000..64cd5cf
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.040.adm
@@ -0,0 +1,6 @@
+{ "values": [ "", 6 ] }
+{ "values": [ "2", 2 ] }
+{ "values": [ "3.5", 3 ] }
+{ "values": [ "4", 4 ] }
+{ "values": [ "5", 5 ] }
+{ "values": [ "s", 1 ] }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.041.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.041.adm
new file mode 100644
index 0000000..64cd5cf
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.041.adm
@@ -0,0 +1,6 @@
+{ "values": [ "", 6 ] }
+{ "values": [ "2", 2 ] }
+{ "values": [ "3.5", 3 ] }
+{ "values": [ "4", 4 ] }
+{ "values": [ "5", 5 ] }
+{ "values": [ "s", 1 ] }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.042.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.042.adm
new file mode 100644
index 0000000..1674d82
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.042.adm
@@ -0,0 +1,6 @@
+{ "values": [ null, 1 ] }
+{ "values": [ 0, 6 ] }
+{ "values": [ 2, 2 ] }
+{ "values": [ 3, 3 ] }
+{ "values": [ 4, 4 ] }
+{ "values": [ 5, 5 ] }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.043.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.043.adm
new file mode 100644
index 0000000..97e4e83
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.043.adm
@@ -0,0 +1,6 @@
+{ "values": [ null, 5 ] }
+{ "values": [ 6 ] }
+{ "values": [ "2", 2 ] }
+{ "values": [ "3.5", 3 ] }
+{ "values": [ "4", 4 ] }
+{ "values": [ "s", 1 ] }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.044.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.044.adm
new file mode 100644
index 0000000..feca349
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.044.adm
@@ -0,0 +1,6 @@
+{ "values": [ null, 5 ] }
+{ "values": [ null, 6 ] }
+{ "values": [ "2", 2 ] }
+{ "values": [ "3.5", 3 ] }
+{ "values": [ "4", 4 ] }
+{ "values": [ "s", 1 ] }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.045.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.045.adm
new file mode 100644
index 0000000..8d8fe2a
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.045.adm
@@ -0,0 +1,6 @@
+{ "values": [ null, 1 ] }
+{ "values": [ null, 5 ] }
+{ "values": [ null, 6 ] }
+{ "values": [ 2, 2 ] }
+{ "values": [ 3, 3 ] }
+{ "values": [ 4, 4 ] }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.046.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.046.adm
new file mode 100644
index 0000000..f03683f
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.046.adm
@@ -0,0 +1,6 @@
+{ "values": [ null, 5 ] }
+{ "values": [ null, 6 ] }
+{ "values": [ 1, 1 ] }
+{ "values": [ 2, 2 ] }
+{ "values": [ 3, 3 ] }
+{ "values": [ 4, 4 ] }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.047.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.047.adm
new file mode 100644
index 0000000..12f73b1
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.047.adm
@@ -0,0 +1,6 @@
+{ "values": [ null, 5 ] }
+{ "values": [ null, 6 ] }
+{ "values": [ "1", 1 ] }
+{ "values": [ "2", 2 ] }
+{ "values": [ "3", 3 ] }
+{ "values": [ "4", 4 ] }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.048.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.048.adm
new file mode 100644
index 0000000..086d8cb
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.048.adm
@@ -0,0 +1,3 @@
+{ "values": [ 2, 2 ] }
+{ "values": [ 3, 3 ] }
+{ "values": [ 4, 4 ] }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.049.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.049.adm
new file mode 100644
index 0000000..086d8cb
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.049.adm
@@ -0,0 +1,3 @@
+{ "values": [ 2, 2 ] }
+{ "values": [ 3, 3 ] }
+{ "values": [ 4, 4 ] }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.050.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.050.adm
new file mode 100644
index 0000000..99eb793
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/ddl/index-cast-null/index-cast-null.050.adm
@@ -0,0 +1,18 @@
+{ "IndexName": "idx1", "SearchKey": [ [ "s_f1" ] ] }
+{ "IndexName": "idx10", "SearchKey": [ [ "s_f1" ] ], "SearchKeyType": [ "string" ], "Cast": { "Default": null } }
+{ "IndexName": "idx11", "SearchKey": [ [ "s_f1" ] ], "SearchKeyType": [ "int64" ], "Cast": { "Default": null } }
+{ "IndexName": "idx12", "SearchKey": [ [ "s_f2" ] ] }
+{ "IndexName": "idx13", "SearchKey": [ [ "s_f2" ] ], "SearchKeyType": [ "string" ], "Cast": { "Default": null } }
+{ "IndexName": "idx14", "SearchKey": [ [ "s_f2" ] ], "SearchKeyType": [ "int64" ], "Cast": { "Default": null } }
+{ "IndexName": "idx15", "SearchKey": [ [ "i_f" ] ], "SearchKeyType": [ "int64" ], "Cast": { "Default": null } }
+{ "IndexName": "idx16", "SearchKey": [ [ "i_f" ] ], "SearchKeyType": [ "string" ], "Cast": { "Default": null } }
+{ "IndexName": "idx2", "SearchKey": [ [ "s_f1" ] ], "SearchKeyType": [ "string" ], "Cast": { "Default": null } }
+{ "IndexName": "idx3", "SearchKey": [ [ "s_f1" ] ], "SearchKeyType": [ "int64" ], "Cast": { "Default": null } }
+{ "IndexName": "idx4", "SearchKey": [ [ "s_f2" ] ] }
+{ "IndexName": "idx5", "SearchKey": [ [ "s_f2" ] ], "SearchKeyType": [ "string" ], "Cast": { "Default": null } }
+{ "IndexName": "idx6", "SearchKey": [ [ "s_f2" ] ], "SearchKeyType": [ "int64" ], "Cast": { "Default": null } }
+{ "IndexName": "idx7", "SearchKey": [ [ "i_f" ] ], "SearchKeyType": [ "int64" ], "Cast": { "Default": null } }
+{ "IndexName": "idx8", "SearchKey": [ [ "i_f" ] ], "SearchKeyType": [ "string" ], "Cast": { "Default": null } }
+{ "IndexName": "idx9", "SearchKey": [ [ "s_f1" ] ] }
+{ "IndexName": "idx_exc1", "SearchKey": [ [ "s_f2" ] ], "SearchKeyType": [ "int64" ], "Cast": { "Default": null } }
+{ "IndexName": "idx_exc2", "SearchKey": [ [ "s_f2" ] ], "SearchKeyType": [ "int64" ], "Cast": { "Default": null } }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/index-selection/cast-default-null/cast-default-null.19.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/index-selection/cast-default-null/cast-default-null.19.adm
new file mode 100644
index 0000000..49938d5
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/index-selection/cast-default-null/cast-default-null.19.adm
@@ -0,0 +1,2 @@
+{ "id": 2, "s_f2": "2" }
+{ "id": 3, "s_f2": "3.5" }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/index-selection/cast-default-null/cast-default-null.20.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/index-selection/cast-default-null/cast-default-null.20.adm
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/index-selection/cast-default-null/cast-default-null.20.adm
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/index-selection/cast-default-null/cast-default-null.21.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/index-selection/cast-default-null/cast-default-null.21.adm
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/index-selection/cast-default-null/cast-default-null.21.adm
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/index-selection/cast-default-null/cast-default-null.22.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/index-selection/cast-default-null/cast-default-null.22.adm
new file mode 100644
index 0000000..78954d0
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/index-selection/cast-default-null/cast-default-null.22.adm
@@ -0,0 +1,2 @@
+{ "id": 2, "s_f2": 2 }
+{ "id": 3, "s_f2": 3 }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/index-selection/cast-default-null/cast-default-null.23.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/index-selection/cast-default-null/cast-default-null.23.adm
new file mode 100644
index 0000000..49938d5
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/index-selection/cast-default-null/cast-default-null.23.adm
@@ -0,0 +1,2 @@
+{ "id": 2, "s_f2": "2" }
+{ "id": 3, "s_f2": "3.5" }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml b/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml
index 4cafa0e..8801ce7 100644
--- a/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml
@@ -4318,10 +4318,10 @@
     <test-case FilePath="ddl">
       <compilation-unit name="index-cast-null-negative">
         <output-dir compare="Text">index-cast-null-negative</output-dir>
-        <expected-error>Cast Default Null is only allowed for B-Tree indexes</expected-error>
-        <expected-error>Cast Default Null cannot be specified together with ENFORCED</expected-error>
-        <expected-error>CAST is not allowed since field "[typed_f1]" is typed</expected-error>
-        <expected-error>CAST is not allowed since field "[typed_f2]" is typed</expected-error>
+        <expected-error>CAST modifier is only allowed for B-Tree indexes</expected-error>
+        <expected-error>CAST modifier cannot be specified together with ENFORCED</expected-error>
+        <expected-error>CAST modifier is used without specifying the type of the indexed field</expected-error>
+        <expected-error>Typed index on "[typed_f2]" field could be created only for open datatype</expected-error>
         <expected-error>Parameter invalid_date cannot be set</expected-error>
       </compilation-unit>
     </test-case>
diff --git a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/declared/BTreeResourceFactoryProvider.java b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/declared/BTreeResourceFactoryProvider.java
index 6276044..168b56e 100644
--- a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/declared/BTreeResourceFactoryProvider.java
+++ b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/declared/BTreeResourceFactoryProvider.java
@@ -146,7 +146,7 @@
             } else {
                 sourceType = metaType;
             }
-            Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(
+            Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(index,
                     indexDetails.getKeyFieldTypes().get(i), indexDetails.getKeyFieldNames().get(i), sourceType);
             IAType keyType = keyTypePair.first;
             secondaryTypeTraits[i] = typeTraitProvider.getTypeTrait(keyType);
@@ -183,7 +183,7 @@
             } else {
                 sourceType = metaType;
             }
-            Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(
+            Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(index,
                     indexDetails.getKeyFieldTypes().get(i), indexDetails.getKeyFieldNames().get(i), sourceType);
             IAType keyType = keyTypePair.first;
             secondaryCmpFactories[i] = cmpFactoryProvider.getBinaryComparatorFactory(keyType, true);
diff --git a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/declared/MetadataProvider.java b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/declared/MetadataProvider.java
index 5ce97eb..4cc83ab 100644
--- a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/declared/MetadataProvider.java
+++ b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/declared/MetadataProvider.java
@@ -68,7 +68,6 @@
 import org.apache.asterix.external.provider.AdapterFactoryProvider;
 import org.apache.asterix.external.util.ExternalDataConstants;
 import org.apache.asterix.formats.base.IDataFormat;
-import org.apache.asterix.formats.nontagged.BinaryComparatorFactoryProvider;
 import org.apache.asterix.formats.nontagged.BinaryIntegerInspector;
 import org.apache.asterix.formats.nontagged.LinearizeComparatorFactoryProvider;
 import org.apache.asterix.formats.nontagged.TypeTraitProvider;
@@ -140,7 +139,6 @@
 import org.apache.hyracks.algebricks.runtime.base.IScalarEvaluatorFactory;
 import org.apache.hyracks.algebricks.runtime.operators.std.SinkWriterRuntimeFactory;
 import org.apache.hyracks.api.dataflow.IOperatorDescriptor;
-import org.apache.hyracks.api.dataflow.value.IBinaryComparatorFactory;
 import org.apache.hyracks.api.dataflow.value.ILinearizeComparatorFactory;
 import org.apache.hyracks.api.dataflow.value.IMissingWriterFactory;
 import org.apache.hyracks.api.dataflow.value.IResultSerializerFactory;
@@ -647,8 +645,8 @@
             ARecordType recType = (ARecordType) findType(dataset.getItemTypeDataverseName(), dataset.getItemTypeName());
             List<List<String>> secondaryKeyFields = secondaryIndexDetails.getKeyFieldNames();
             List<IAType> secondaryKeyTypes = secondaryIndexDetails.getKeyFieldTypes();
-            Pair<IAType, Boolean> keyTypePair =
-                    Index.getNonNullableOpenFieldType(secondaryKeyTypes.get(0), secondaryKeyFields.get(0), recType);
+            Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(secondaryIndex,
+                    secondaryKeyTypes.get(0), secondaryKeyFields.get(0), recType);
             IAType keyType = keyTypePair.first;
             int numDimensions = NonTaggedFormatUtil.getNumDimensions(keyType.getTypeTag());
             int numNestedSecondaryKeyFields = numDimensions * 2;
@@ -1066,53 +1064,6 @@
         return new Pair<>(dataScanner, constraint);
     }
 
-    private Pair<IBinaryComparatorFactory[], ITypeTraits[]> getComparatorFactoriesAndTypeTraitsOfSecondaryBTreeIndex(
-            List<List<String>> sidxKeyFieldNames, List<IAType> sidxKeyFieldTypes, List<List<String>> pidxKeyFieldNames,
-            ARecordType recType, DatasetType dsType, boolean hasMeta, List<Integer> primaryIndexKeyIndicators,
-            List<Integer> secondaryIndexIndicators, ARecordType metaType) throws AlgebricksException {
-
-        IBinaryComparatorFactory[] comparatorFactories;
-        ITypeTraits[] typeTraits;
-        int sidxKeyFieldCount = sidxKeyFieldNames.size();
-        int pidxKeyFieldCount = pidxKeyFieldNames.size();
-        typeTraits = new ITypeTraits[sidxKeyFieldCount + pidxKeyFieldCount];
-        comparatorFactories = new IBinaryComparatorFactory[sidxKeyFieldCount + pidxKeyFieldCount];
-
-        int i = 0;
-        for (; i < sidxKeyFieldCount; ++i) {
-            Pair<IAType, Boolean> keyPairType =
-                    Index.getNonNullableOpenFieldType(sidxKeyFieldTypes.get(i), sidxKeyFieldNames.get(i),
-                            (hasMeta && secondaryIndexIndicators.get(i).intValue() == 1) ? metaType : recType);
-            IAType keyType = keyPairType.first;
-            comparatorFactories[i] = BinaryComparatorFactoryProvider.INSTANCE.getBinaryComparatorFactory(keyType, true);
-            typeTraits[i] = TypeTraitProvider.INSTANCE.getTypeTrait(keyType);
-        }
-
-        for (int j = 0; j < pidxKeyFieldCount; ++j, ++i) {
-            IAType keyType = null;
-            try {
-                switch (dsType) {
-                    case INTERNAL:
-                        keyType = (hasMeta && primaryIndexKeyIndicators.get(j).intValue() == 1)
-                                ? metaType.getSubFieldType(pidxKeyFieldNames.get(j))
-                                : recType.getSubFieldType(pidxKeyFieldNames.get(j));
-                        break;
-                    case EXTERNAL:
-                        keyType = IndexingConstants.getFieldType(j);
-                        break;
-                    default:
-                        throw new CompilationException(ErrorCode.COMPILATION_UNKNOWN_DATASET_TYPE, dsType.toString());
-                }
-            } catch (AsterixException e) {
-                throw new AlgebricksException(e);
-            }
-            comparatorFactories[i] = BinaryComparatorFactoryProvider.INSTANCE.getBinaryComparatorFactory(keyType, true);
-            typeTraits[i] = TypeTraitProvider.INSTANCE.getTypeTrait(keyType);
-        }
-
-        return new Pair<>(comparatorFactories, typeTraits);
-    }
-
     private Pair<IOperatorDescriptor, AlgebricksPartitionConstraint> getInsertOrDeleteRuntime(IndexOperation indexOp,
             IDataSource<DataSourceId> dataSource, IOperatorSchema propagatedSchema, List<LogicalVariable> keys,
             LogicalVariable payload, List<LogicalVariable> additionalNonKeyFields, RecordDescriptor inputRecordDesc,
@@ -1447,8 +1398,8 @@
         Index.ValueIndexDetails secondaryIndexDetails = (Index.ValueIndexDetails) secondaryIndex.getIndexDetails();
         List<List<String>> secondaryKeyExprs = secondaryIndexDetails.getKeyFieldNames();
         List<IAType> secondaryKeyTypes = secondaryIndexDetails.getKeyFieldTypes();
-        Pair<IAType, Boolean> keyPairType =
-                Index.getNonNullableOpenFieldType(secondaryKeyTypes.get(0), secondaryKeyExprs.get(0), recType);
+        Pair<IAType, Boolean> keyPairType = Index.getNonNullableOpenFieldType(secondaryIndex, secondaryKeyTypes.get(0),
+                secondaryKeyExprs.get(0), recType);
         IAType spatialType = keyPairType.first;
         int dimension = NonTaggedFormatUtil.getNumDimensions(spatialType.getTypeTag());
         int numSecondaryKeys = dimension * 2;
@@ -1759,8 +1710,8 @@
             // return the derived type.
             // e.g. UNORDERED LIST -> return UNORDERED LIST type
             IAType secondaryKeyType;
-            Pair<IAType, Boolean> keyPairType = Index.getNonNullableOpenFieldType(secondaryKeyTypeEntries.get(0),
-                    secondaryKeyExprs.get(0), recType);
+            Pair<IAType, Boolean> keyPairType = Index.getNonNullableOpenFieldType(secondaryIndex,
+                    secondaryKeyTypeEntries.get(0), secondaryKeyExprs.get(0), recType);
             secondaryKeyType = keyPairType.first;
             List<List<String>> partitioningKeys = dataset.getPrimaryKeys();
             i = 0;
diff --git a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/entities/Index.java b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/entities/Index.java
index b00ca82..9e67292 100644
--- a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/entities/Index.java
+++ b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/entities/Index.java
@@ -32,6 +32,7 @@
 import org.apache.asterix.common.transactions.IRecoveryManager.ResourceType;
 import org.apache.asterix.metadata.MetadataCache;
 import org.apache.asterix.metadata.api.IMetadataEntity;
+import org.apache.asterix.metadata.utils.IndexUtil;
 import org.apache.asterix.om.types.ARecordType;
 import org.apache.asterix.om.types.AUnionType;
 import org.apache.asterix.om.types.IAType;
@@ -154,8 +155,13 @@
         return new Pair<>(actualKeyType, nullable);
     }
 
-    public static Pair<IAType, Boolean> getNonNullableOpenFieldType(IAType fieldType, List<String> fieldName,
-            ARecordType recType) throws AlgebricksException {
+    public static Pair<IAType, Boolean> getNonNullableOpenFieldType(Index index, IAType fieldType,
+            List<String> fieldName, ARecordType recType) throws AlgebricksException {
+        if (IndexUtil.castDefaultNull(index)) {
+            Pair<IAType, Boolean> nonNullableType = getNonNullableType(fieldType);
+            nonNullableType.second = true;
+            return nonNullableType;
+        }
         Pair<IAType, Boolean> keyPairType = null;
         IAType subType = recType;
         boolean nullable = false;
diff --git a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/ArrayIndexUtil.java b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/ArrayIndexUtil.java
index 7282c7d..1abf300 100644
--- a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/ArrayIndexUtil.java
+++ b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/ArrayIndexUtil.java
@@ -240,7 +240,7 @@
      * Traverse each distinct record path and invoke the appropriate commands for each scenario. Here, we keep track
      * of the record/list type at each step and give this to each command.
      */
-    public static void walkArrayPath(ARecordType baseRecordType, List<String> flattenedFieldName,
+    public static void walkArrayPath(Index index, ARecordType baseRecordType, List<String> flattenedFieldName,
             List<Boolean> unnestFlags, TypeTrackerCommandExecutor commandExecutor) throws AlgebricksException {
         ArrayPath arrayPath = new ArrayPath(flattenedFieldName, unnestFlags).invoke();
         List<List<String>> fieldNamesPerArray = arrayPath.fieldNamesPerArray;
@@ -266,8 +266,9 @@
                     // Determine whether we have an open field or not. Extract the type appropriately.
                     isTrackingType = isTrackingType && intermediateRecordType.doesFieldExist(fieldPart);
                     if (isTrackingType) {
-                        workingType = Index.getNonNullableOpenFieldType(intermediateRecordType.getFieldType(fieldPart),
-                                Collections.singletonList(fieldPart), intermediateRecordType).first;
+                        workingType =
+                                Index.getNonNullableOpenFieldType(index, intermediateRecordType.getFieldType(fieldPart),
+                                        Collections.singletonList(fieldPart), intermediateRecordType).first;
                         if (workingType instanceof ARecordType) {
                             // We have an intermediate step, set our record step for the next loop iteration.
                             intermediateRecordType = (ARecordType) workingType;
diff --git a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/InvertedIndexResourceFactoryProvider.java b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/InvertedIndexResourceFactoryProvider.java
index 970c5a8..a75a75d 100644
--- a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/InvertedIndexResourceFactoryProvider.java
+++ b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/InvertedIndexResourceFactoryProvider.java
@@ -185,8 +185,8 @@
         } else {
             sourceType = metaType;
         }
-        Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(indexDetails.getKeyFieldTypes().get(0),
-                indexDetails.getKeyFieldNames().get(0), sourceType);
+        Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(index,
+                indexDetails.getKeyFieldTypes().get(0), indexDetails.getKeyFieldNames().get(0), sourceType);
         IAType secondaryKeyType = keyTypePair.first;
         int numTokenFields = (!isPartitioned) ? numSecondaryKeys : numSecondaryKeys + 1;
         ITypeTraits[] tokenTypeTraits = new ITypeTraits[numTokenFields];
@@ -222,8 +222,8 @@
         } else {
             sourceType = metaType;
         }
-        Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(indexDetails.getKeyFieldTypes().get(0),
-                indexDetails.getKeyFieldNames().get(0), sourceType);
+        Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(index,
+                indexDetails.getKeyFieldTypes().get(0), indexDetails.getKeyFieldNames().get(0), sourceType);
         IAType secondaryKeyType = keyTypePair.first;
         // Comparators and type traits for tokens.
         int numTokenFields = (!isPartitioned) ? numSecondaryKeys : numSecondaryKeys + 1;
@@ -258,8 +258,8 @@
         } else {
             sourceType = metaType;
         }
-        Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(indexDetails.getKeyFieldTypes().get(0),
-                indexDetails.getKeyFieldNames().get(0), sourceType);
+        Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(index,
+                indexDetails.getKeyFieldTypes().get(0), indexDetails.getKeyFieldNames().get(0), sourceType);
         IAType secondaryKeyType = keyTypePair.first;
         // Set tokenizer factory.
         // TODO: We might want to expose the hashing option at the AQL level,
diff --git a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/KeyFieldTypeUtil.java b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/KeyFieldTypeUtil.java
index 6a0c44f..61effa8 100644
--- a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/KeyFieldTypeUtil.java
+++ b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/KeyFieldTypeUtil.java
@@ -133,7 +133,7 @@
         List<Integer> keySourceIndicators = indexDetails.getKeyFieldSourceIndicators();
         List<IAType> indexKeyTypes = new ArrayList<>();
         for (int i = 0; i < indexDetails.getKeyFieldNames().size(); i++) {
-            Pair<IAType, Boolean> keyPairType = Index.getNonNullableOpenFieldType(
+            Pair<IAType, Boolean> keyPairType = Index.getNonNullableOpenFieldType(index,
                     indexDetails.getKeyFieldTypes().get(i), indexDetails.getKeyFieldNames().get(i),
                     chooseSource(keySourceIndicators, i, recordType, metaRecordType));
             indexKeyTypes.add(keyPairType.first);
@@ -178,8 +178,8 @@
         List<Integer> keySourceIndicators = indexDetails.getKeyFieldSourceIndicators();
         List<IAType> indexKeyTypes = new ArrayList<>();
         ARecordType targetRecType = chooseSource(keySourceIndicators, 0, recordType, metaRecordType);
-        Pair<IAType, Boolean> keyPairType = Index.getNonNullableOpenFieldType(indexDetails.getKeyFieldTypes().get(0),
-                indexDetails.getKeyFieldNames().get(0), targetRecType);
+        Pair<IAType, Boolean> keyPairType = Index.getNonNullableOpenFieldType(index,
+                indexDetails.getKeyFieldTypes().get(0), indexDetails.getKeyFieldNames().get(0), targetRecType);
         IAType keyType = keyPairType.first;
         IAType nestedKeyType = NonTaggedFormatUtil.getNestedSpatialType(keyType.getTypeTag());
         int numKeys = KeyFieldTypeUtil.getNumSecondaryKeys(index, targetRecType, metaRecordType);
@@ -217,7 +217,7 @@
             case RTREE:
                 Index.ValueIndexDetails indexDetails = (Index.ValueIndexDetails) index.getIndexDetails();
                 List<Integer> keySourceIndicators = indexDetails.getKeyFieldSourceIndicators();
-                Pair<IAType, Boolean> keyPairType = Index.getNonNullableOpenFieldType(
+                Pair<IAType, Boolean> keyPairType = Index.getNonNullableOpenFieldType(index,
                         indexDetails.getKeyFieldTypes().get(0), indexDetails.getKeyFieldNames().get(0),
                         chooseSource(keySourceIndicators, 0, recordType, metaRecordType));
                 IAType keyType = keyPairType.first;
diff --git a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/RTreeResourceFactoryProvider.java b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/RTreeResourceFactoryProvider.java
index 22f968a..463cffb 100644
--- a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/RTreeResourceFactoryProvider.java
+++ b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/RTreeResourceFactoryProvider.java
@@ -78,7 +78,7 @@
             throw new CompilationException(ErrorCode.COMPILATION_ILLEGAL_INDEX_NUM_OF_FIELD,
                     indexDetails.getKeyFieldNames().size(), index.getIndexType(), 1);
         }
-        IAType spatialType = Index.getNonNullableOpenFieldType(indexDetails.getKeyFieldTypes().get(0),
+        IAType spatialType = Index.getNonNullableOpenFieldType(index, indexDetails.getKeyFieldTypes().get(0),
                 indexDetails.getKeyFieldNames().get(0), recordType).first;
         if (spatialType == null) {
             throw new CompilationException(ErrorCode.COMPILATION_FIELD_NOT_FOUND,
@@ -211,7 +211,7 @@
         } else {
             sourceType = metaType;
         }
-        Pair<IAType, Boolean> spatialTypePair = Index.getNonNullableOpenFieldType(
+        Pair<IAType, Boolean> spatialTypePair = Index.getNonNullableOpenFieldType(index,
                 indexDetails.getKeyFieldTypes().get(0), secondaryKeyFields.get(0), sourceType);
         IAType spatialType = spatialTypePair.first;
         if (spatialType == null) {
@@ -248,7 +248,7 @@
         } else {
             sourceType = metaType;
         }
-        Pair<IAType, Boolean> spatialTypePair = Index.getNonNullableOpenFieldType(
+        Pair<IAType, Boolean> spatialTypePair = Index.getNonNullableOpenFieldType(index,
                 indexDetails.getKeyFieldTypes().get(0), secondaryKeyFields.get(0), sourceType);
         IAType spatialType = spatialTypePair.first;
         if (spatialType == null) {
diff --git a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryArrayIndexBTreeOperationsHelper.java b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryArrayIndexBTreeOperationsHelper.java
index 32138dc..c8a7ee1 100644
--- a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryArrayIndexBTreeOperationsHelper.java
+++ b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryArrayIndexBTreeOperationsHelper.java
@@ -245,7 +245,7 @@
         } else {
             EvalFactoryAndRecDescInvoker commandExecutor =
                     new EvalFactoryAndRecDescInvoker(!evalFactoryAndRecDescStackBuilder.isUnnestEvalPopulated());
-            ArrayIndexUtil.walkArrayPath(recordType, flattenedFieldName, workingUnnestFlags, commandExecutor);
+            ArrayIndexUtil.walkArrayPath(index, recordType, flattenedFieldName, workingUnnestFlags, commandExecutor);
         }
     }
 
@@ -515,7 +515,7 @@
     }
 
     private void addAtomicFieldToBuilder(ARecordType recordType, int indexPos) throws AlgebricksException {
-        IAType workingType = Index.getNonNullableOpenFieldType(flattenedKeyTypes.get(indexPos),
+        IAType workingType = Index.getNonNullableOpenFieldType(index, flattenedKeyTypes.get(indexPos),
                 flattenedFieldNames.get(indexPos), recordType).first;
         IScalarEvaluatorFactory sef =
                 metadataProvider.getDataFormat().getFieldAccessEvaluatorFactory(metadataProvider.getFunctionManager(),
diff --git a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryBTreeOperationsHelper.java b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryBTreeOperationsHelper.java
index bb1bd40..c3e2394 100644
--- a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryBTreeOperationsHelper.java
+++ b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryBTreeOperationsHelper.java
@@ -242,12 +242,11 @@
             }
             secondaryFieldAccessEvalFactories[i] = createFieldAccessors(i, isOverridingKeyFieldTypes, enforcedType,
                     sourceType, sourceColumn, indexDetails, indexDetails.getKeyFieldTypes().get(i));
-            Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(
+            Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(index,
                     indexDetails.getKeyFieldTypes().get(i), indexDetails.getKeyFieldNames().get(i), sourceType);
             IAType keyType = keyTypePair.first;
             anySecondaryKeyIsNullable = anySecondaryKeyIsNullable || keyTypePair.second;
-            ISerializerDeserializer keySerde = serdeProvider.getSerializerDeserializer(keyType);
-            secondaryRecFields[i] = keySerde;
+            secondaryRecFields[i] = serdeProvider.getSerializerDeserializer(keyType);
             secondaryComparatorFactories[i] = comparatorFactoryProvider.getBinaryComparatorFactory(keyType, true);
             secondaryTypeTraits[i] = typeTraitProvider.getTypeTrait(keyType);
             secondaryBloomFilterKeyFields[i] = i;
@@ -306,7 +305,11 @@
         IDataFormat dataFormat = metadataProvider.getDataFormat();
         IScalarEvaluatorFactory fieldEvalFactory = dataFormat.getFieldAccessEvaluatorFactory(funManger, recordType,
                 indexDetails.getKeyFieldNames().get(field), recordColumn, sourceLoc);
-        boolean castIndexedField = isOverridingKeyFieldTypes && !enforcedRecordType.equals(recordType);
+        // check IndexUtil.castDefaultNull(index), too, because we always want to cast even if the overriding type is
+        // the same as the overridden type (this is for the case where overriding the type of closed field is allowed)
+        // e.g. field "a" is a string in the dataset ds; CREATE INDEX .. ON ds(a:string) CAST (DEFAULT NULL)
+        boolean castIndexedField = isOverridingKeyFieldTypes
+                && (!enforcedRecordType.equals(recordType) || IndexUtil.castDefaultNull(index));
         if (!castIndexedField) {
             return fieldEvalFactory;
         }
diff --git a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryCorrelatedBTreeOperationsHelper.java b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryCorrelatedBTreeOperationsHelper.java
index aca953b..6e5bc17 100644
--- a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryCorrelatedBTreeOperationsHelper.java
+++ b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryCorrelatedBTreeOperationsHelper.java
@@ -161,7 +161,7 @@
             secondaryFieldAccessEvalFactories[i] = metadataProvider.getDataFormat().getFieldAccessEvaluatorFactory(
                     metadataProvider.getFunctionManager(), isOverridingKeyTypes ? enforcedItemType : sourceType,
                     indexDetails.getKeyFieldNames().get(i), sourceColumn, sourceLoc);
-            Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(
+            Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(index,
                     indexDetails.getKeyFieldTypes().get(i), indexDetails.getKeyFieldNames().get(i), sourceType);
             IAType keyType = keyTypePair.first;
             anySecondaryKeyIsNullable = anySecondaryKeyIsNullable || keyTypePair.second;
diff --git a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryCorrelatedInvertedIndexOperationsHelper.java b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryCorrelatedInvertedIndexOperationsHelper.java
index c111f0e..a50f50c 100644
--- a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryCorrelatedInvertedIndexOperationsHelper.java
+++ b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryCorrelatedInvertedIndexOperationsHelper.java
@@ -116,7 +116,7 @@
             secondaryFieldAccessEvalFactories[0] = metadataProvider.getDataFormat().getFieldAccessEvaluatorFactory(
                     metadataProvider.getFunctionManager(), isOverridingKeyFieldTypes ? enforcedItemType : itemType,
                     indexDetails.getKeyFieldNames().get(0), recordColumn, sourceLoc);
-            Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(
+            Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(index,
                     indexDetails.getKeyFieldTypes().get(0), indexDetails.getKeyFieldNames().get(0), itemType);
             secondaryKeyType = keyTypePair.first;
             anySecondaryKeyIsNullable = anySecondaryKeyIsNullable || keyTypePair.second;
diff --git a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryCorrelatedRTreeOperationsHelper.java b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryCorrelatedRTreeOperationsHelper.java
index 82c67d7..ff5b021 100644
--- a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryCorrelatedRTreeOperationsHelper.java
+++ b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryCorrelatedRTreeOperationsHelper.java
@@ -83,7 +83,7 @@
             throw AsterixException.create(ErrorCode.INDEX_RTREE_MULTIPLE_FIELDS_NOT_ALLOWED, sourceLoc,
                     numSecondaryKeys);
         }
-        Pair<IAType, Boolean> spatialTypePair = Index.getNonNullableOpenFieldType(
+        Pair<IAType, Boolean> spatialTypePair = Index.getNonNullableOpenFieldType(index,
                 indexDetails.getKeyFieldTypes().get(0), secondaryKeyFields.get(0), itemType);
         IAType spatialType = spatialTypePair.first;
         anySecondaryKeyIsNullable = spatialTypePair.second;
diff --git a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryInvertedIndexOperationsHelper.java b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryInvertedIndexOperationsHelper.java
index 67f58a5..a84454f 100644
--- a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryInvertedIndexOperationsHelper.java
+++ b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryInvertedIndexOperationsHelper.java
@@ -120,7 +120,7 @@
             secondaryFieldAccessEvalFactories[0] = metadataProvider.getDataFormat().getFieldAccessEvaluatorFactory(
                     metadataProvider.getFunctionManager(), isOverridingKeyFieldTypes ? enforcedItemType : itemType,
                     indexDetails.getKeyFieldNames().get(0), numPrimaryKeys, sourceLoc);
-            Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(
+            Pair<IAType, Boolean> keyTypePair = Index.getNonNullableOpenFieldType(index,
                     indexDetails.getKeyFieldTypes().get(0), indexDetails.getKeyFieldNames().get(0), itemType);
             secondaryKeyType = keyTypePair.first;
             anySecondaryKeyIsNullable = anySecondaryKeyIsNullable || keyTypePair.second;
diff --git a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryRTreeOperationsHelper.java b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryRTreeOperationsHelper.java
index e4b5cf8..e36e71f 100644
--- a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryRTreeOperationsHelper.java
+++ b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/SecondaryRTreeOperationsHelper.java
@@ -89,7 +89,7 @@
             throw new AsterixException("Cannot use " + numSecondaryKeys + " fields as a key for the R-tree index. "
                     + "There can be only one field as a key for the R-tree index.");
         }
-        Pair<IAType, Boolean> spatialTypePair = Index.getNonNullableOpenFieldType(
+        Pair<IAType, Boolean> spatialTypePair = Index.getNonNullableOpenFieldType(index,
                 indexDetails.getKeyFieldTypes().get(0), secondaryKeyFields.get(0), itemType);
         IAType spatialType = spatialTypePair.first;
         anySecondaryKeyIsNullable = spatialTypePair.second;
diff --git a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/TypeUtil.java b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/TypeUtil.java
index 570757e..cef963f 100644
--- a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/TypeUtil.java
+++ b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/utils/TypeUtil.java
@@ -192,13 +192,15 @@
         private String bridgeNameFoundFromOpenTypeBuild;
         private IAType endOfOpenTypeBuild;
         private int indexOfOpenPart;
+        private boolean castDefaultNull;
 
         public void reset(ARecordType baseRecordType, List<String> keyFieldNames, List<Boolean> keyUnnestFlags,
-                IAType keyFieldType) {
+                IAType keyFieldType, boolean castDefaultNull) {
             this.baseRecordType = baseRecordType;
             this.keyFieldNames = keyFieldNames;
             this.keyUnnestFlags = keyUnnestFlags;
             this.keyFieldType = keyFieldType;
+            this.castDefaultNull = castDefaultNull;
         }
 
         public ARecordType build() throws AlgebricksException {
@@ -301,12 +303,16 @@
                     && ((AUnionType) enforcedFieldType).isUnknownableType()) {
                 enforcedFieldType = ((AUnionType) enforcedFieldType).getActualType();
             }
-            if (enforcedFieldType != null
-                    && !ATypeHierarchy.canPromote(enforcedFieldType.getTypeTag(), this.keyFieldType.getTypeTag())) {
-                throw new AsterixException(ErrorCode.COMPILATION_ERROR, "Cannot enforce field \""
-                        + String.join(".", this.keyFieldNames) + "\" to have type " + this.keyFieldType);
-            }
-            if (enforcedFieldType == null) {
+            if (enforcedFieldType != null) {
+                // choose the type specified in the DDL over the type in the dataset schema if CAST is used
+                if (castDefaultNull) {
+                    recordNameTypesMap.put(keyFieldNames.get(keyFieldNames.size() - 1),
+                            nestArrayType(keyFieldType, isKeyTypeWithUnnest));
+                } else if (!ATypeHierarchy.canPromote(enforcedFieldType.getTypeTag(), this.keyFieldType.getTypeTag())) {
+                    throw new AsterixException(ErrorCode.COMPILATION_ERROR, "Cannot enforce field \""
+                            + String.join(".", this.keyFieldNames) + "\" to have type " + this.keyFieldType);
+                }
+            } else {
                 recordNameTypesMap.put(keyFieldNames.get(keyFieldNames.size() - 1),
                         AUnionType.createUnknownableType(nestArrayType(keyFieldType, isKeyTypeWithUnnest)));
             }
@@ -425,7 +431,8 @@
                         "Indexing an open field is only supported on the record part");
             }
             enforcedTypeBuilder.reset(enforcedRecordType, keyFieldNames.get(i),
-                    Collections.nCopies(keyFieldNames.get(i).size(), false), keyFieldTypes.get(i));
+                    Collections.nCopies(keyFieldNames.get(i).size(), false), keyFieldTypes.get(i),
+                    valueIndexDetails.getCastDefaultNull().getOrElse(false));
             validateRecord(enforcedRecordType);
             enforcedRecordType = enforcedTypeBuilder.build();
         }
@@ -445,7 +452,7 @@
                         "Indexing an open field is only supported on the record part");
             }
             enforcedTypeBuilder.reset(enforcedRecordType, keyFieldNames.get(i),
-                    Collections.nCopies(keyFieldNames.get(i).size(), false), keyFieldTypes.get(i));
+                    Collections.nCopies(keyFieldNames.get(i).size(), false), keyFieldTypes.get(i), false);
             validateRecord(enforcedRecordType);
             enforcedRecordType = enforcedTypeBuilder.build();
         }
@@ -468,7 +475,7 @@
                 List<String> project = projectList.get(i);
                 enforcedTypeBuilder.reset(enforcedRecordType,
                         ArrayIndexUtil.getFlattenedKeyFieldNames(unnestList, project),
-                        ArrayIndexUtil.getUnnestFlags(unnestList, project), typeList.get(i));
+                        ArrayIndexUtil.getUnnestFlags(unnestList, project), typeList.get(i), false);
                 validateRecord(enforcedRecordType);
                 enforcedRecordType = enforcedTypeBuilder.build();
             }