diff --git a/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/ConstantFoldingRule.java b/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/ConstantFoldingRule.java
index e99817d..0c2eeba 100644
--- a/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/ConstantFoldingRule.java
+++ b/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/ConstantFoldingRule.java
@@ -85,6 +85,7 @@
 import org.apache.hyracks.algebricks.core.config.AlgebricksConfig;
 import org.apache.hyracks.algebricks.core.jobgen.impl.JobGenContext;
 import org.apache.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule;
+import org.apache.hyracks.algebricks.core.rewriter.base.PhysicalOptimizationConfig;
 import org.apache.hyracks.algebricks.runtime.base.IEvaluatorContext;
 import org.apache.hyracks.algebricks.runtime.base.IScalarEvaluator;
 import org.apache.hyracks.algebricks.runtime.base.IScalarEvaluatorFactory;
@@ -151,7 +152,7 @@
                 UnnestingPositionWriterFactory.INSTANCE, null,
                 new ExpressionRuntimeProvider(new QueryLogicalExpressionJobGen(metadataProvider.getFunctionManager())),
                 ExpressionTypeComputer.INSTANCE, null, null, null, null, GlobalConfig.DEFAULT_FRAME_SIZE, null,
-                NoOpWarningCollector.INSTANCE, 0);
+                NoOpWarningCollector.INSTANCE, 0, new PhysicalOptimizationConfig());
     }
 
     @Override
diff --git a/asterixdb/asterix-app/src/main/java/org/apache/asterix/api/common/APIFramework.java b/asterixdb/asterix-app/src/main/java/org/apache/asterix/api/common/APIFramework.java
index 0091304..919a24e 100644
--- a/asterixdb/asterix-app/src/main/java/org/apache/asterix/api/common/APIFramework.java
+++ b/asterixdb/asterix-app/src/main/java/org/apache/asterix/api/common/APIFramework.java
@@ -135,7 +135,8 @@
             CompilerProperties.COMPILER_SORTMEMORY_KEY, CompilerProperties.COMPILER_WINDOWMEMORY_KEY,
             CompilerProperties.COMPILER_TEXTSEARCHMEMORY_KEY, CompilerProperties.COMPILER_PARALLELISM_KEY,
             CompilerProperties.COMPILER_SORT_PARALLEL_KEY, CompilerProperties.COMPILER_SORT_SAMPLES_KEY,
-            CompilerProperties.COMPILER_INDEXONLY_KEY, CompilerProperties.COMPILER_INTERNAL_SANITYCHECK_KEY,
+            CompilerProperties.COMPILER_EXTERNALSCANMEMORY_KEY, CompilerProperties.COMPILER_INDEXONLY_KEY,
+            CompilerProperties.COMPILER_INTERNAL_SANITYCHECK_KEY,
             CompilerProperties.COMPILER_EXTERNAL_FIELD_PUSHDOWN_KEY, CompilerProperties.COMPILER_SUBPLAN_MERGE_KEY,
             CompilerProperties.COMPILER_SUBPLAN_NESTEDPUSHDOWN_KEY,
             CompilerProperties.COMPILER_MIN_MEMORY_ALLOCATION_KEY, FunctionUtil.IMPORT_PRIVATE_FUNCTIONS,
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.000.ddl.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.000.ddl.sqlpp
new file mode 100644
index 0000000..22a30ca
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.000.ddl.sqlpp
@@ -0,0 +1,66 @@
+/*
+ * 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;
+
+drop type test if exists;
+create type test as open {
+};
+
+drop dataset test1 if exists;
+create external dataset test1(test) using S3 (
+("accessKeyId"="dummyAccessKey"),
+("secretAccessKey"="dummySecretKey"),
+("region"="us-west-2"),
+("serviceEndpoint"="http://localhost:8001"),
+("container"="playground"),
+("definition"="json-data/reviews/single-line/json"),
+("format"="json"));
+
+drop dataset test2 if exists;
+create external dataset test2(test) using S3 (
+("accessKeyId"="dummyAccessKey"),
+("secretAccessKey"="dummySecretKey"),
+("region"="us-west-2"),
+("serviceEndpoint"="http://localhost:8001"),
+("container"="playground"),
+("definition"="json-data/reviews/multi-lines/json"),
+("format"="json"));
+
+drop dataset test3 if exists;
+create external dataset test3(test) using S3 (
+("accessKeyId"="dummyAccessKey"),
+("secretAccessKey"="dummySecretKey"),
+("region"="us-west-2"),
+("serviceEndpoint"="http://localhost:8001"),
+("container"="playground"),
+("definition"="json-data/reviews/multi-lines-with-arrays/json"),
+("format"="json"));
+
+drop dataset test4 if exists;
+create external dataset test4(test) using S3 (
+("accessKeyId"="dummyAccessKey"),
+("secretAccessKey"="dummySecretKey"),
+("region"="us-west-2"),
+("serviceEndpoint"="http://localhost:8001"),
+("container"="playground"),
+("definition"="json-data/reviews/multi-lines-with-nested-objects/json"),
+("format"="json"));
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.001.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.001.query.sqlpp
new file mode 100644
index 0000000..7c1708a
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.001.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;
+set `compiler.externalscanmemory` "8KB";
+select count(*) `count` from test1;
+
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.002.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.002.query.sqlpp
new file mode 100644
index 0000000..d122f42
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.002.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;
+set `compiler.externalscanmemory` "16KB";
+select count(*) `count` from test2;
+
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.003.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.003.query.sqlpp
new file mode 100644
index 0000000..552f943
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.003.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;
+set `compiler.externalscanmemory` "32KB";
+select count(*) `count` from test3;
+
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.004.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.004.query.sqlpp
new file mode 100644
index 0000000..f30af80
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.004.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;
+set `compiler.externalscanmemory` "8KB";
+select value test3 from test3 order by id;
+
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.005.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.005.query.sqlpp
new file mode 100644
index 0000000..af6aff0
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.005.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;
+set `compiler.externalscanmemory` "16KB";
+select count(*) `count` from test4;
+
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.006.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.006.query.sqlpp
new file mode 100644
index 0000000..854ac80
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.006.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;
+set `compiler.externalscanmemory` "10KB";
+select value test4 from test4 order by id;
+
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.999.ddl.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.999.ddl.sqlpp
new file mode 100644
index 0000000..548e632
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/external-dataset/common/custom-buffer-size/external_dataset.999.ddl.sqlpp
@@ -0,0 +1,20 @@
+/*
+ * 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;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/external-dataset/common/custom-buffer-size/external_dataset.001.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/external-dataset/common/custom-buffer-size/external_dataset.001.adm
new file mode 100644
index 0000000..187a8cb
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/external-dataset/common/custom-buffer-size/external_dataset.001.adm
@@ -0,0 +1 @@
+{ "count": 100 }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/external-dataset/common/custom-buffer-size/external_dataset.002.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/external-dataset/common/custom-buffer-size/external_dataset.002.adm
new file mode 100644
index 0000000..187a8cb
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/external-dataset/common/custom-buffer-size/external_dataset.002.adm
@@ -0,0 +1 @@
+{ "count": 100 }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/external-dataset/common/custom-buffer-size/external_dataset.003.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/external-dataset/common/custom-buffer-size/external_dataset.003.adm
new file mode 100644
index 0000000..5db606c
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/external-dataset/common/custom-buffer-size/external_dataset.003.adm
@@ -0,0 +1 @@
+{ "count": 25 }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/external-dataset/common/custom-buffer-size/external_dataset.004.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/external-dataset/common/custom-buffer-size/external_dataset.004.adm
new file mode 100644
index 0000000..7660e7e
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/external-dataset/common/custom-buffer-size/external_dataset.004.adm
@@ -0,0 +1,25 @@
+{ "id": 1, "year": null, "quarter": null, "review": "good", "array": [ 1, 2, 3 ] }
+{ "id": 1, "year": null, "quarter": null, "review": "good", "array": [ 1, 2, 3 ] }
+{ "id": 1, "year": null, "quarter": null, "review": "good", "array": [ 1, 2, 3 ] }
+{ "id": 1, "year": null, "quarter": null, "review": "good", "array": [ 1, 2, 3 ] }
+{ "id": 1, "year": null, "quarter": null, "review": "good", "array": [ 1, 2, 3 ] }
+{ "id": 2, "year": null, "quarter": null, "review": "good", "array": [ 1, [ 1, 2 ], [ 1 ] ] }
+{ "id": 2, "year": null, "quarter": null, "review": "good", "array": [ 1, [ 1, 2 ], [ 1 ] ] }
+{ "id": 2, "year": null, "quarter": null, "review": "good", "array": [ 1, [ 1, 2 ], [ 1 ] ] }
+{ "id": 2, "year": null, "quarter": null, "review": "good", "array": [ 1, [ 1, 2 ], [ 1 ] ] }
+{ "id": 2, "year": null, "quarter": null, "review": "good", "array": [ 1, [ 1, 2 ], [ 1 ] ] }
+{ "id": 3, "year": 2018, "quarter": null, "review": "good", "array": [ 1, 2, 3 ] }
+{ "id": 3, "year": 2018, "quarter": null, "review": "good", "array": [ 1, 2, 3 ] }
+{ "id": 3, "year": 2018, "quarter": null, "review": "good", "array": [ 1, 2, 3 ] }
+{ "id": 3, "year": 2018, "quarter": null, "review": "good", "array": [ 1, 2, 3 ] }
+{ "id": 3, "year": 2018, "quarter": null, "review": "good", "array": [ 1, 2, 3 ] }
+{ "id": 4, "year": 2018, "quarter": null, "review": "bad", "array": [ 1, 2, 3 ] }
+{ "id": 4, "year": 2018, "quarter": null, "review": "bad", "array": [ 1, 2, 3 ] }
+{ "id": 4, "year": 2018, "quarter": null, "review": "bad", "array": [ 1, 2, 3 ] }
+{ "id": 4, "year": 2018, "quarter": null, "review": "bad", "array": [ 1, 2, 3 ] }
+{ "id": 4, "year": 2018, "quarter": null, "review": "bad", "array": [ 1, 2, 3 ] }
+{ "id": 5, "year": 2018, "quarter": 1, "review": "good", "array": [ 1, 2, 3 ] }
+{ "id": 5, "year": 2018, "quarter": 1, "review": "good", "array": [ 1, 2, 3 ] }
+{ "id": 5, "year": 2018, "quarter": 1, "review": "good", "array": [ 1, 2, 3 ] }
+{ "id": 5, "year": 2018, "quarter": 1, "review": "good", "array": [ 1, 2, 3 ] }
+{ "id": 5, "year": 2018, "quarter": 1, "review": "good", "array": [ 1, 2, 3 ] }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/external-dataset/common/custom-buffer-size/external_dataset.005.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/external-dataset/common/custom-buffer-size/external_dataset.005.adm
new file mode 100644
index 0000000..5db606c
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/external-dataset/common/custom-buffer-size/external_dataset.005.adm
@@ -0,0 +1 @@
+{ "count": 25 }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/external-dataset/common/custom-buffer-size/external_dataset.006.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/external-dataset/common/custom-buffer-size/external_dataset.006.adm
new file mode 100644
index 0000000..7643986
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/external-dataset/common/custom-buffer-size/external_dataset.006.adm
@@ -0,0 +1,25 @@
+{ "id": 1, "year": null, "quarter": null, "review": "good", "array": [ 1, 2, 3 ], "nested": { "id": 1 } }
+{ "id": 1, "year": null, "quarter": null, "review": "good", "array": [ 1, 2, 3 ], "nested": { "id": 1 } }
+{ "id": 1, "year": null, "quarter": null, "review": "good", "array": [ 1, 2, 3 ], "nested": { "id": 1 } }
+{ "id": 1, "year": null, "quarter": null, "review": "good", "array": [ 1, 2, 3 ], "nested": { "id": 1 } }
+{ "id": 1, "year": null, "quarter": null, "review": "good", "array": [ 1, 2, 3 ], "nested": { "id": 1 } }
+{ "id": 2, "year": null, "quarter": null, "review": "good", "array": [ 1, [ 1, 2 ], [ 1 ] ], "nested": { "id": 1 }, "nested2": [ { "id": 1 } ] }
+{ "id": 2, "year": null, "quarter": null, "review": "good", "array": [ 1, [ 1, 2 ], [ 1 ] ], "nested": { "id": 1 }, "nested2": [ { "id": 1 } ] }
+{ "id": 2, "year": null, "quarter": null, "review": "good", "array": [ 1, [ 1, 2 ], [ 1 ] ], "nested": { "id": 1 }, "nested2": [ { "id": 1 } ] }
+{ "id": 2, "year": null, "quarter": null, "review": "good", "array": [ 1, [ 1, 2 ], [ 1 ] ], "nested": { "id": 1 }, "nested2": [ { "id": 1 } ] }
+{ "id": 2, "year": null, "quarter": null, "review": "good", "array": [ 1, [ 1, 2 ], [ 1 ] ], "nested": { "id": 1 }, "nested2": [ { "id": 1 } ] }
+{ "id": 3, "year": 2018, "quarter": null, "review": "good", "array": [ 1, 2, 3, { "nested": { "array": [ { "nested": { "array": [ 1, 2 ] } } ] } } ] }
+{ "id": 3, "year": 2018, "quarter": null, "review": "good", "array": [ 1, 2, 3, { "nested": { "array": [ { "nested": { "array": [ 1, 2 ] } } ] } } ] }
+{ "id": 3, "year": 2018, "quarter": null, "review": "good", "array": [ 1, 2, 3, { "nested": { "array": [ { "nested": { "array": [ 1, 2 ] } } ] } } ] }
+{ "id": 3, "year": 2018, "quarter": null, "review": "good", "array": [ 1, 2, 3, { "nested": { "array": [ { "nested": { "array": [ 1, 2 ] } } ] } } ] }
+{ "id": 3, "year": 2018, "quarter": null, "review": "good", "array": [ 1, 2, 3, { "nested": { "array": [ { "nested": { "array": [ 1, 2 ] } } ] } } ] }
+{ "id": 4, "year": 2018, "quarter": null, "review": "bad", "array": [ 1, 2, 3, { "nested1": { "id": 1, "nested2": { "id": 2, "nested3": [ { "nested4": null } ] } } } ] }
+{ "id": 4, "year": 2018, "quarter": null, "review": "bad", "array": [ 1, 2, 3, { "nested1": { "id": 1, "nested2": { "id": 2, "nested3": [ { "nested4": null } ] } } } ] }
+{ "id": 4, "year": 2018, "quarter": null, "review": "bad", "array": [ 1, 2, 3, { "nested1": { "id": 1, "nested2": { "id": 2, "nested3": [ { "nested4": null } ] } } } ] }
+{ "id": 4, "year": 2018, "quarter": null, "review": "bad", "array": [ 1, 2, 3, { "nested1": { "id": 1, "nested2": { "id": 2, "nested3": [ { "nested4": null } ] } } } ] }
+{ "id": 4, "year": 2018, "quarter": null, "review": "bad", "array": [ 1, 2, 3, { "nested1": { "id": 1, "nested2": { "id": 2, "nested3": [ { "nested4": null } ] } } } ] }
+{ "id": 5, "year": 2018, "quarter": 1, "review": "good", "array": [ 1, 2, 3, { "nested": { "array": [ 1, 2 ] } } ] }
+{ "id": 5, "year": 2018, "quarter": 1, "review": "good", "array": [ 1, 2, 3, { "nested": { "array": [ 1, 2 ] } } ] }
+{ "id": 5, "year": 2018, "quarter": 1, "review": "good", "array": [ 1, 2, 3, { "nested": { "array": [ 1, 2 ] } } ] }
+{ "id": 5, "year": 2018, "quarter": 1, "review": "good", "array": [ 1, 2, 3, { "nested": { "array": [ 1, 2 ] } } ] }
+{ "id": 5, "year": 2018, "quarter": 1, "review": "good", "array": [ 1, 2, 3, { "nested": { "array": [ 1, 2 ] } } ] }
\ No newline at end of file
diff --git a/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/config/CompilerProperties.java b/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/config/CompilerProperties.java
index 866d183..a58673f 100644
--- a/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/config/CompilerProperties.java
+++ b/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/config/CompilerProperties.java
@@ -55,6 +55,10 @@
                 LONG_BYTE_UNIT,
                 StorageUtil.getLongSizeInBytes(32L, MEGABYTE),
                 "The memory budget (in bytes) for an inverted-index-search operator instance in a partition"),
+        COMPILER_EXTERNALSCANMEMORY(
+                INTEGER_BYTE_UNIT,
+                StorageUtil.getIntSizeInBytes(8, KILOBYTE),
+                "The memory budget (in bytes) for an external scan operator instance in a partition"),
         COMPILER_FRAMESIZE(
                 INTEGER_BYTE_UNIT,
                 StorageUtil.getIntSizeInBytes(32, KILOBYTE),
@@ -126,6 +130,11 @@
         public Object defaultValue() {
             return defaultValue;
         }
+
+        @Override
+        public boolean hidden() {
+            return this == COMPILER_EXTERNALSCANMEMORY;
+        }
     }
 
     public static final String COMPILER_SORTMEMORY_KEY = Option.COMPILER_SORTMEMORY.ini();
@@ -156,6 +165,8 @@
 
     public static final String COMPILER_MIN_MEMORY_ALLOCATION_KEY = Option.COMPILER_MIN_MEMORY_ALLOCATION.ini();
 
+    public static final String COMPILER_EXTERNALSCANMEMORY_KEY = Option.COMPILER_EXTERNALSCANMEMORY.ini();
+
     public static final int COMPILER_PARALLELISM_AS_STORAGE = 0;
 
     public CompilerProperties(PropertiesAccessor accessor) {
@@ -221,4 +232,8 @@
     public boolean getMinMemoryAllocation() {
         return accessor.getBoolean(Option.COMPILER_MIN_MEMORY_ALLOCATION);
     }
+
+    public int getExternalScanMemorySize() {
+        return accessor.getInt(Option.COMPILER_EXTERNALSCANMEMORY);
+    }
 }
diff --git a/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/config/OptimizationConfUtil.java b/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/config/OptimizationConfUtil.java
index 8832054..c4dbd85 100644
--- a/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/config/OptimizationConfUtil.java
+++ b/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/config/OptimizationConfUtil.java
@@ -72,7 +72,9 @@
                 CompilerProperties.COMPILER_SUBPLAN_NESTEDPUSHDOWN_KEY, compilerProperties.getSubplanNestedPushdown());
         boolean minMemoryAllocation = getBoolean(querySpecificConfig,
                 CompilerProperties.COMPILER_MIN_MEMORY_ALLOCATION_KEY, compilerProperties.getMinMemoryAllocation());
-
+        int externalScanBufferSize = getExternalScanBufferSize(
+                (String) querySpecificConfig.get(CompilerProperties.COMPILER_EXTERNALSCANMEMORY_KEY),
+                compilerProperties.getExternalScanMemorySize(), sourceLoc);
         PhysicalOptimizationConfig physOptConf = new PhysicalOptimizationConfig();
         physOptConf.setFrameSize(frameSize);
         physOptConf.setMaxFramesExternalSort(sortFrameLimit);
@@ -88,9 +90,21 @@
         physOptConf.setSubplanMerge(subplanMerge);
         physOptConf.setSubplanNestedPushdown(subplanNestedPushdown);
         physOptConf.setMinMemoryAllocation(minMemoryAllocation);
+        physOptConf.setExternalScanBufferSize(externalScanBufferSize);
         return physOptConf;
     }
 
+    private static int getExternalScanBufferSize(String externalScanMemorySizeParameter,
+            int compilerExternalScanMemorySize, SourceLocation sourceLoc) throws AsterixException {
+        IOptionType<Integer> intByteParser = OptionTypes.INTEGER_BYTE_UNIT;
+        try {
+            return externalScanMemorySizeParameter != null ? intByteParser.parse(externalScanMemorySizeParameter)
+                    : compilerExternalScanMemorySize;
+        } catch (IllegalArgumentException e) {
+            throw AsterixException.create(ErrorCode.COMPILATION_ERROR, sourceLoc, e.getMessage());
+        }
+    }
+
     public static int getSortNumFrames(CompilerProperties compilerProperties, Map<String, Object> querySpecificConfig,
             SourceLocation sourceLoc) throws AlgebricksException {
         return getFrameLimit(CompilerProperties.COMPILER_SORTMEMORY_KEY,
diff --git a/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/input/record/reader/aws/AwsS3InputStream.java b/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/input/record/reader/aws/AwsS3InputStream.java
index 4288cc4..5eb8475 100644
--- a/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/input/record/reader/aws/AwsS3InputStream.java
+++ b/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/input/record/reader/aws/AwsS3InputStream.java
@@ -45,8 +45,9 @@
 
 public class AwsS3InputStream extends AbstractExternalInputStream {
 
-    private final S3Client s3Client;
+    // Configuration
     private final String bucket;
+    private final S3Client s3Client;
     private static final int MAX_RETRIES = 5; // We will retry 5 times in case of internal error from AWS S3 service
 
     public AwsS3InputStream(Map<String, String> configuration, List<String> filePaths) throws HyracksDataException {
@@ -60,13 +61,11 @@
         String fileName = filePaths.get(nextFileIndex);
         GetObjectRequest.Builder getObjectBuilder = GetObjectRequest.builder();
         GetObjectRequest getObjectRequest = getObjectBuilder.bucket(bucket).key(filePaths.get(nextFileIndex)).build();
-
         // Have a reference to the S3 stream to ensure that if GZipInputStream causes an IOException because of reading
         // the header, then the S3 stream gets closed in the close method
         if (!doGetInputStream(getObjectRequest)) {
             return false;
         }
-
         // Use gzip stream if needed
         if (StringUtils.endsWithIgnoreCase(fileName, ".gz") || StringUtils.endsWithIgnoreCase(fileName, ".gzip")) {
             in = new GZIPInputStream(in, ExternalDataConstants.DEFAULT_BUFFER_SIZE);
diff --git a/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/input/record/reader/stream/StreamRecordReader.java b/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/input/record/reader/stream/StreamRecordReader.java
index cb16de5..1e003a1 100644
--- a/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/input/record/reader/stream/StreamRecordReader.java
+++ b/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/input/record/reader/stream/StreamRecordReader.java
@@ -33,7 +33,6 @@
 import org.apache.asterix.external.dataflow.AbstractFeedDataFlowController;
 import org.apache.asterix.external.input.record.CharArrayRecord;
 import org.apache.asterix.external.input.stream.AsterixInputStreamReader;
-import org.apache.asterix.external.util.ExternalDataConstants;
 import org.apache.asterix.external.util.ExternalDataUtils;
 import org.apache.asterix.external.util.FeedLogManager;
 import org.apache.hyracks.api.context.IHyracksTaskContext;
@@ -51,9 +50,10 @@
     private Supplier<String> previousDataSourceName = EMPTY_STRING;
 
     public void configure(AsterixInputStream inputStream, Map<String, String> config) {
-        this.reader = new AsterixInputStreamReader(inputStream);
+        int bufferSize = ExternalDataUtils.getOrDefaultBufferSize(config);
+        this.reader = new AsterixInputStreamReader(inputStream, bufferSize);
         record = new CharArrayRecord();
-        inputBuffer = new char[ExternalDataConstants.DEFAULT_BUFFER_SIZE];
+        inputBuffer = new char[bufferSize];
         if (!ExternalDataUtils.isTrue(config, KEY_REDACT_WARNINGS)) {
             this.dataSourceName = reader::getStreamName;
             this.previousDataSourceName = reader::getPreviousStreamName;
diff --git a/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/input/stream/AsterixInputStreamReader.java b/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/input/stream/AsterixInputStreamReader.java
index d2499f8..81da0b0 100644
--- a/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/input/stream/AsterixInputStreamReader.java
+++ b/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/input/stream/AsterixInputStreamReader.java
@@ -27,25 +27,24 @@
 
 import org.apache.asterix.external.api.AsterixInputStream;
 import org.apache.asterix.external.dataflow.AbstractFeedDataFlowController;
-import org.apache.asterix.external.util.ExternalDataConstants;
 import org.apache.asterix.external.util.FeedLogManager;
 import org.apache.hyracks.api.exceptions.HyracksDataException;
 
 public class AsterixInputStreamReader extends Reader {
     private final AsterixInputStream in;
     private final CharsetDecoder decoder;
-    private final byte[] bytes;
+    private byte[] bytes;
     protected final ByteBuffer byteBuffer;
     protected final CharBuffer charBuffer;
     protected boolean done = false;
     protected boolean remaining = false;
 
-    public AsterixInputStreamReader(AsterixInputStream in) {
+    public AsterixInputStreamReader(AsterixInputStream in, int bufferSize) {
         this.in = in;
         this.decoder = StandardCharsets.UTF_8.newDecoder();
-        bytes = new byte[ExternalDataConstants.DEFAULT_BUFFER_SIZE];
-        byteBuffer = ByteBuffer.wrap(bytes);
-        charBuffer = CharBuffer.allocate(ExternalDataConstants.DEFAULT_BUFFER_SIZE);
+        this.bytes = new byte[bufferSize];
+        this.byteBuffer = ByteBuffer.wrap(bytes);
+        this.charBuffer = CharBuffer.allocate(bufferSize);
         this.byteBuffer.flip();
     }
 
diff --git a/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/input/stream/StandardUTF8ToModifiedUTF8DataOutput.java b/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/input/stream/StandardUTF8ToModifiedUTF8DataOutput.java
index be0d286..adeb80e 100644
--- a/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/input/stream/StandardUTF8ToModifiedUTF8DataOutput.java
+++ b/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/input/stream/StandardUTF8ToModifiedUTF8DataOutput.java
@@ -141,7 +141,7 @@
         private final ByteArrayAccessibleInputStream inByte;
 
         public ResettableUTF8InputStreamReader(ByteArrayAccessibleInputStream inByte) {
-            super(new BasicInputStream(inByte));
+            super(new BasicInputStream(inByte), ExternalDataConstants.DEFAULT_BUFFER_SIZE);
             this.inByte = inByte;
         }
 
diff --git a/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/util/ExternalDataConstants.java b/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/util/ExternalDataConstants.java
index 047fe2a..a0cf387 100644
--- a/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/util/ExternalDataConstants.java
+++ b/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/util/ExternalDataConstants.java
@@ -120,6 +120,7 @@
     public static final String KEY_NULL_STR = "null";
     public static final String KEY_REDACT_WARNINGS = "redact-warnings";
     public static final String KEY_REQUESTED_FIELDS = "requested-fields";
+    public static final String KEY_EXTERNAL_SCAN_BUFFER_SIZE = "external-scan-buffer-size";
 
     /**
      * Keys for adapter name
diff --git a/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/util/ExternalDataUtils.java b/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/util/ExternalDataUtils.java
index 2d25d08..4beb932 100644
--- a/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/util/ExternalDataUtils.java
+++ b/asterixdb/asterix-external-data/src/main/java/org/apache/asterix/external/util/ExternalDataUtils.java
@@ -32,6 +32,7 @@
 import static org.apache.asterix.external.util.ExternalDataConstants.AzureBlob.SHARED_ACCESS_SIGNATURE_FIELD_NAME;
 import static org.apache.asterix.external.util.ExternalDataConstants.KEY_DELIMITER;
 import static org.apache.asterix.external.util.ExternalDataConstants.KEY_ESCAPE;
+import static org.apache.asterix.external.util.ExternalDataConstants.KEY_EXTERNAL_SCAN_BUFFER_SIZE;
 import static org.apache.asterix.external.util.ExternalDataConstants.KEY_QUOTE;
 import static org.apache.asterix.external.util.ExternalDataConstants.KEY_RECORD_END;
 import static org.apache.asterix.external.util.ExternalDataConstants.KEY_RECORD_START;
@@ -114,6 +115,11 @@
     private ExternalDataUtils() {
     }
 
+    public static int getOrDefaultBufferSize(Map<String, String> configuration) {
+        String bufferSize = configuration.get(KEY_EXTERNAL_SCAN_BUFFER_SIZE);
+        return bufferSize != null ? Integer.parseInt(bufferSize) : ExternalDataConstants.DEFAULT_BUFFER_SIZE;
+    }
+
     // Get a delimiter from the given configuration
     public static char validateGetDelimiter(Map<String, String> configuration) throws HyracksDataException {
         return validateCharOrDefault(configuration, KEY_DELIMITER, ExternalDataConstants.DEFAULT_DELIMITER.charAt(0));
diff --git a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/declared/DatasetDataSource.java b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/declared/DatasetDataSource.java
index 29a66b9..17f91b4 100644
--- a/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/declared/DatasetDataSource.java
+++ b/asterixdb/asterix-metadata/src/main/java/org/apache/asterix/metadata/declared/DatasetDataSource.java
@@ -18,6 +18,8 @@
  */
 package org.apache.asterix.metadata.declared;
 
+import static org.apache.asterix.external.util.ExternalDataConstants.KEY_EXTERNAL_SCAN_BUFFER_SIZE;
+
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -44,6 +46,7 @@
 import org.apache.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
 import org.apache.hyracks.algebricks.core.algebra.properties.INodeDomain;
 import org.apache.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import org.apache.hyracks.algebricks.core.rewriter.base.PhysicalOptimizationConfig;
 import org.apache.hyracks.api.dataflow.IOperatorDescriptor;
 import org.apache.hyracks.api.job.JobSpecification;
 import org.apache.hyracks.storage.am.common.api.ITupleFilterFactory;
@@ -109,7 +112,10 @@
                         externalDataset.getItemTypeDataverseName(), itemTypeName).getDatatype();
 
                 ExternalDatasetDetails edd = (ExternalDatasetDetails) externalDataset.getDatasetDetails();
+                PhysicalOptimizationConfig physicalOptimizationConfig = context.getPhysicalOptimizationConfig();
+                int externalScanBufferSize = physicalOptimizationConfig.getExternalScanBufferSize();
                 Map<String, String> properties = addProjectionInfo(projectionInfo, edd.getProperties());
+                properties.put(KEY_EXTERNAL_SCAN_BUFFER_SIZE, String.valueOf(externalScanBufferSize));
                 ITypedAdapterFactory adapterFactory = metadataProvider.getConfiguredAdapterFactory(externalDataset,
                         edd.getAdapter(), properties, (ARecordType) itemType, null, context.getWarningCollector());
                 return metadataProvider.buildExternalDatasetDataScannerRuntime(jobSpec, itemType, adapterFactory,
diff --git a/hyracks-fullstack/algebricks/algebricks-compiler/src/main/java/org/apache/hyracks/algebricks/compiler/api/HeuristicCompilerFactoryBuilder.java b/hyracks-fullstack/algebricks/algebricks-compiler/src/main/java/org/apache/hyracks/algebricks/compiler/api/HeuristicCompilerFactoryBuilder.java
index 49be31c..c6a79a5 100644
--- a/hyracks-fullstack/algebricks/algebricks-compiler/src/main/java/org/apache/hyracks/algebricks/compiler/api/HeuristicCompilerFactoryBuilder.java
+++ b/hyracks-fullstack/algebricks/algebricks-compiler/src/main/java/org/apache/hyracks/algebricks/compiler/api/HeuristicCompilerFactoryBuilder.java
@@ -106,8 +106,7 @@
                                 expressionRuntimeProvider, expressionTypeComputer, oc, expressionEvalSizeComputer,
                                 partialAggregationTypeComputer, predEvaluatorFactoryProvider,
                                 physicalOptimizationConfig.getFrameSize(), clusterLocations, warningCollector,
-                                maxWarnings);
-
+                                maxWarnings, physicalOptimizationConfig);
                         PlanCompiler pc = new PlanCompiler(context);
                         return pc.compilePlan(plan, jobEventListenerFactory);
                     }
diff --git a/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/config/AlgebricksConfig.java b/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/config/AlgebricksConfig.java
index c99117b..817db5a 100644
--- a/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/config/AlgebricksConfig.java
+++ b/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/config/AlgebricksConfig.java
@@ -18,6 +18,7 @@
  */
 package org.apache.hyracks.algebricks.core.config;
 
+import org.apache.hyracks.util.StorageUtil;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
@@ -33,4 +34,6 @@
     public static final boolean SUBPLAN_MERGE_DEFAULT = true;
     public static final boolean SUBPLAN_NESTEDPUSHDOWN_DEFAULT = true;
     public static final boolean MIN_MEMORY_ALLOCATION_DEFAULT = true;
+    public static final int EXTERNAL_SCAN_BUFFER_SIZE =
+            StorageUtil.getIntSizeInBytes(8, StorageUtil.StorageUnit.KILOBYTE);
 }
diff --git a/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/jobgen/impl/JobGenContext.java b/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/jobgen/impl/JobGenContext.java
index 41cde2e..2ca4a36 100644
--- a/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/jobgen/impl/JobGenContext.java
+++ b/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/jobgen/impl/JobGenContext.java
@@ -34,6 +34,7 @@
 import org.apache.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
 import org.apache.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
 import org.apache.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import org.apache.hyracks.algebricks.core.rewriter.base.PhysicalOptimizationConfig;
 import org.apache.hyracks.algebricks.data.IBinaryBooleanInspectorFactory;
 import org.apache.hyracks.algebricks.data.IBinaryComparatorFactoryProvider;
 import org.apache.hyracks.algebricks.data.IBinaryHashFunctionFactoryProvider;
@@ -70,6 +71,7 @@
     private final IPartialAggregationTypeComputer partialAggregationTypeComputer;
     private final IPredicateEvaluatorFactoryProvider predEvaluatorFactoryProvider;
     private final int frameSize;
+    private final PhysicalOptimizationConfig physicalOptimizationConfig;
     private AlgebricksAbsolutePartitionConstraint clusterLocations;
     private int varCounter;
     private final ITypingContext typingContext;
@@ -90,7 +92,7 @@
             IPartialAggregationTypeComputer partialAggregationTypeComputer,
             IPredicateEvaluatorFactoryProvider predEvaluatorFactoryProvider, int frameSize,
             AlgebricksAbsolutePartitionConstraint clusterLocations, IWarningCollector warningCollector,
-            long maxWarnings) {
+            long maxWarnings, PhysicalOptimizationConfig physicalOptimizationConfig) {
         this.outerFlowSchema = outerFlowSchema;
         this.metadataProvider = metadataProvider;
         this.appContext = appContext;
@@ -113,6 +115,7 @@
         this.partialAggregationTypeComputer = partialAggregationTypeComputer;
         this.predEvaluatorFactoryProvider = predEvaluatorFactoryProvider;
         this.frameSize = frameSize;
+        this.physicalOptimizationConfig = physicalOptimizationConfig;
         this.varCounter = 0;
         this.warningCollector = warningCollector;
         this.maxWarnings = maxWarnings;
@@ -227,4 +230,8 @@
     public long getMaxWarnings() {
         return maxWarnings;
     }
+
+    public PhysicalOptimizationConfig getPhysicalOptimizationConfig() {
+        return physicalOptimizationConfig;
+    }
 }
diff --git a/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/rewriter/base/PhysicalOptimizationConfig.java b/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/rewriter/base/PhysicalOptimizationConfig.java
index 92f579c..bfff925 100644
--- a/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/rewriter/base/PhysicalOptimizationConfig.java
+++ b/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/rewriter/base/PhysicalOptimizationConfig.java
@@ -45,6 +45,7 @@
     private static final String SUBPLAN_MERGE = "SUBPLAN_MERGE";
     private static final String SUBPLAN_NESTEDPUSHDOWN = "SUBPLAN_NESTEDPUSHDOWN";
     private static final String MIN_MEMORY_ALLOCATION = "MIN_MEMORY_ALLOCATION";
+    private static final String EXTERNAL_SCAN_BUFFER_SIZE = "EXTERNAL_SCAN_BUFFER_SIZE";
 
     private final Properties properties = new Properties();
 
@@ -226,6 +227,14 @@
         setBoolean(MIN_MEMORY_ALLOCATION, value);
     }
 
+    public int getExternalScanBufferSize() {
+        return getInt(EXTERNAL_SCAN_BUFFER_SIZE, AlgebricksConfig.EXTERNAL_SCAN_BUFFER_SIZE);
+    }
+
+    public void setExternalScanBufferSize(int bufferSize) {
+        setInt(EXTERNAL_SCAN_BUFFER_SIZE, bufferSize);
+    }
+
     private void setInt(String property, int value) {
         properties.setProperty(property, Integer.toString(value));
     }