diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/string/position/position.1.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/string/position/position.1.adm
index 76e3e97..5c54d04 100644
--- a/asterixdb/asterix-app/src/test/resources/runtimets/results/string/position/position.1.adm
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/string/position/position.1.adm
@@ -1 +1 @@
-[ 2, -1 ]
+[ 3, -1 ]
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/string/regexp_position/regexp_position.1.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/string/regexp_position/regexp_position.1.adm
index 428917f..83ee615 100644
--- a/asterixdb/asterix-app/src/test/resources/runtimets/results/string/regexp_position/regexp_position.1.adm
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/string/regexp_position/regexp_position.1.adm
@@ -1,15 +1,15 @@
-0
+1
 -1
-0
-0
-0
+1
+1
+1
 -1
-0
+1
 -1
 -1
-0
-0
-0
-0
+1
+1
+1
+1
 -1
-0
+1
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/string/regexp_position_with_flag/regexp_position_with_flag.1.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/string/regexp_position_with_flag/regexp_position_with_flag.1.adm
index fa99af7..f962896 100644
--- a/asterixdb/asterix-app/src/test/resources/runtimets/results/string/regexp_position_with_flag/regexp_position_with_flag.1.adm
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/string/regexp_position_with_flag/regexp_position_with_flag.1.adm
@@ -1 +1 @@
-{ "result1": 0 }
+{ "result1": 1 }
diff --git a/asterixdb/asterix-doc/pom.xml b/asterixdb/asterix-doc/pom.xml
index 9b980e1..d2fbefc 100644
--- a/asterixdb/asterix-doc/pom.xml
+++ b/asterixdb/asterix-doc/pom.xml
@@ -56,7 +56,7 @@
                   <filelist dir="${project.basedir}/src/main/markdown/sqlpp" files="0_toc.md,1_intro.md,2_expr_title.md,2_expr.md,3_query_title.md,3_query.md,4_error_title.md,4_error.md,5_ddl.md,appendix_1_title.md,appendix_1_keywords.md,appendix_2_title.md,appendix_2_parameters.md" />
                 </concat>
                 <concat destfile="${project.build.directory}/generated-site/markdown/sqlpp/builtins.md">
-                  <filelist dir="${project.basedir}/src/main/markdown/builtins" files="0_toc.md,1_numeric.md,2_string.md,3_binary.md,4_spatial.md,5_similarity.md,6_tokenizing.md,7_temporal.md,7_allens.md,8_record.md,9_aggregate_sql.md,10_comparison.md,11_type.md,13_conditional.md,12_misc.md" />
+                  <filelist dir="${project.basedir}/src/main/markdown/builtins" files="0_toc.md,1_numeric_common.md,1_numeric_delta.md,2_string_common.md,2_string_delta.md,3_binary.md,4_spatial.md,5_similarity.md,6_tokenizing.md,7_temporal.md,7_allens.md,8_record.md,9_aggregate_sql.md,10_comparison.md,11_type.md,13_conditional.md,12_misc.md" />
                 </concat>
                 <concat destfile="${project.build.directory}/generated-site/markdown/aql/builtins.md">
                   <filelist dir="${project.basedir}/src/main/markdown/builtins" files="0_toc.md,1_numeric.md,2_string.md,3_binary.md,4_spatial.md,5_similarity.md,6_tokenizing.md,7_temporal.md,7_allens.md,8_record.md,9_aggregate_aql.md,10_comparison.md,11_type.md,13_conditional.md,12_misc.md" />
diff --git a/asterixdb/asterix-doc/src/main/markdown/builtins/1_numeric.md b/asterixdb/asterix-doc/src/main/markdown/builtins/1_numeric_common.md
similarity index 90%
rename from asterixdb/asterix-doc/src/main/markdown/builtins/1_numeric.md
rename to asterixdb/asterix-doc/src/main/markdown/builtins/1_numeric_common.md
index 563860c..9a4c080 100644
--- a/asterixdb/asterix-doc/src/main/markdown/builtins/1_numeric.md
+++ b/asterixdb/asterix-doc/src/main/markdown/builtins/1_numeric_common.md
@@ -357,44 +357,6 @@
         { "v1": 2013, "v2": -4036, "v3": 1.0, "v4": -2013.0, "v5": -2014.0 }
 
 
-### round_half_to_even ###
- * Syntax:
-
-        round_half_to_even(numeric_value, [precision])
-
- * Computes the closest numeric value to `numeric_value` that is a multiple of ten to the power of minus `precision`.
-   `precision` is optional and by default value `0` is used.
- * Arguments:
-    * `numeric_value`: a `tinyint`/`smallint`/`integer`/`bigint`/`float`/`double` value.
-    * `precision`: an optional `tinyint`/`smallint`/`integer`/`bigint` field representing the
-       number of digits in the fraction of the the result
- * Return Value:
-    * The rounded value for the given number in the same type as the input argument,
-    * `missing` if any argument is a `missing` value,
-    * `null` if any argument is a `null` value but no argument is a `missing` value,
-    * a type error will be raised if:
-        * the first argument is any other non-numeric value,
-        * or, the second argument is any other non-tinyint, non-smallint, non-integer, or non-bigint value.
-
- * Example:
-
-        {
-          "v1": round_half_to_even(2013),
-          "v2": round_half_to_even(-4036),
-          "v3": round_half_to_even(0.8),
-          "v4": round_half_to_even(float("-2013.256")),
-          "v5": round_half_to_even(double("-2013.893823748327284")),
-          "v6": round_half_to_even(double("-2013.893823748327284"), 2),
-          "v7": round_half_to_even(2013, 4),
-          "v8": round_half_to_even(float("-2013.256"), 5)
-        };
-
-
- * The expected result is:
-
-        { "v1": 2013, "v2": -4036, "v3": 1.0, "v4": -2013.0, "v5": -2014.0, "v6": -2013.89, "v7": 2013, "v8": -2013.256 }
-
-
 ### sign ###
  * Syntax:
 
diff --git a/asterixdb/asterix-doc/src/main/markdown/builtins/1_numeric_delta.md b/asterixdb/asterix-doc/src/main/markdown/builtins/1_numeric_delta.md
new file mode 100644
index 0000000..151233e
--- /dev/null
+++ b/asterixdb/asterix-doc/src/main/markdown/builtins/1_numeric_delta.md
@@ -0,0 +1,57 @@
+<!--
+ ! 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.
+ !-->
+
+### round_half_to_even ###
+ * Syntax:
+
+        round_half_to_even(numeric_value, [precision])
+
+ * Computes the closest numeric value to `numeric_value` that is a multiple of ten to the power of minus `precision`.
+   `precision` is optional and by default value `0` is used.
+ * Arguments:
+    * `numeric_value`: a `tinyint`/`smallint`/`integer`/`bigint`/`float`/`double` value.
+    * `precision`: an optional `tinyint`/`smallint`/`integer`/`bigint` field representing the
+       number of digits in the fraction of the the result
+ * Return Value:
+    * The rounded value for the given number in the same type as the input argument,
+    * `missing` if any argument is a `missing` value,
+    * `null` if any argument is a `null` value but no argument is a `missing` value,
+    * a type error will be raised if:
+        * the first argument is any other non-numeric value,
+        * or, the second argument is any other non-tinyint, non-smallint, non-integer, or non-bigint value.
+
+ * Example:
+
+        {
+          "v1": round_half_to_even(2013),
+          "v2": round_half_to_even(-4036),
+          "v3": round_half_to_even(0.8),
+          "v4": round_half_to_even(float("-2013.256")),
+          "v5": round_half_to_even(double("-2013.893823748327284")),
+          "v6": round_half_to_even(double("-2013.893823748327284"), 2),
+          "v7": round_half_to_even(2013, 4),
+          "v8": round_half_to_even(float("-2013.256"), 5)
+        };
+
+
+ * The expected result is:
+
+        { "v1": 2013, "v2": -4036, "v3": 1.0, "v4": -2013.0, "v5": -2014.0, "v6": -2013.89, "v7": 2013, "v8": -2013.256 }
+
+
diff --git a/asterixdb/asterix-doc/src/main/markdown/builtins/2_string.md b/asterixdb/asterix-doc/src/main/markdown/builtins/2_string_common.md
similarity index 77%
rename from asterixdb/asterix-doc/src/main/markdown/builtins/2_string.md
rename to asterixdb/asterix-doc/src/main/markdown/builtins/2_string_common.md
index 605fd8d..95d0550 100644
--- a/asterixdb/asterix-doc/src/main/markdown/builtins/2_string.md
+++ b/asterixdb/asterix-doc/src/main/markdown/builtins/2_string_common.md
@@ -227,7 +227,7 @@
 
  * The expected result is:
 
-        { "v1": 2, "v2": -1 }
+        { "v1": 3, "v2": -1 }
 
 
 ### regexp_contains ###
@@ -322,7 +322,7 @@
 
  * The expected result is:
 
-        { "v1": 0, "v2": -1 }
+        { "v1": 1, "v2": -1 }
 
 
 ### regexp_replace ###
@@ -463,112 +463,6 @@
         { "v1": true, "v2": false }
 
 
-### string_concat ###
- * Syntax:
-
-        string_concat(array)
-
- * Concatenates an array of strings `array` into a single string.
- * Arguments:
-    * `array` : an `array` or `multiset` of `string`s (could be `null` or `missing`) to be concatenated.
- * Return Value:
-    * the concatenated `string` value,
-    * `missing` if the argument is a `missing` value,
-    * `null` if any argument is a `null` value but no argument is a `missing` value,
-    * `missing` if any element in the input array is `missing`,
-    * `null` if any element in the input array is `null` but no element in the input array is `missing`,
-    * any other non-array input value or non-integer element in the input array will cause a type error.
-
- * Example:
-
-        string_concat(["ASTERIX", " ", "ROCKS!"]);
-
-
- * The expected result is:
-
-        "ASTERIX ROCKS!"
-
-
-### string_join ###
- * Syntax:
-
-        string_join(array, string)
-
- * Joins an array or multiset of strings `array` with the given separator `string` into a single string.
- * Arguments:
-    * `array` : an `array` or `multiset` of strings (could be `null`) to be joined.
-    * `string` : a `string` to serve as the separator.
- * Return Value:
-    * the joined `string`,
-    * `missing` if any argument is a `missing` value,
-    * `null` if any argument is a `null` value but no argument is a `missing` value,
-    * `missing` if the first argument array contains a `missing`,
-    * `null` if the first argument array contains a `null` but does not contain a `missing`,
-    * a type error will be raised if:
-        * the first argument is any other non-array value, or contains any other non-string value,
-        * or, the second argument is any other non-string value.
-
- * Example:
-
-        string_join(["ASTERIX", "ROCKS~"], "!! ");
-
-
- * The expected result is:
-
-        "ASTERIX!! ROCKS~"
-
-
-### string_to_codepoint ###
- * Syntax:
-
-        string_to_codepoint(string)
-
- * Converts the string `string` to its code_based representation.
- * Arguments:
-    * `string` : a `string` that will be converted.
- * Return Value:
-    * an `array` of the code points for the string `string`,
-    * `missing` if the argument is a `missing` value,
-    * `null` if the argument is a `null` value,
-    * any other non-string input value will cause a type error.
-
- * Example:
-
-        string_to_codepoint("Hello ASTERIX!");
-
-
- * The expected result is:
-
-        [ 72, 101, 108, 108, 111, 32, 65, 83, 84, 69, 82, 73, 88, 33 ]
-
-
-### codepoint_to_string ###
- * Syntax:
-
-        codepoint_to_string(array)
-
- * Converts the ordered code_based representation `array` to the corresponding string.
- * Arguments:
-    * `array` : an `array` of integer code_points.
- * Return Value:
-    * a `string` representation of `array`.
-    * `missing` if the argument is a `missing` value,
-    * `null` if the argument is a `null` value,
-    * `missing` if any element in the input array is `missing`,
-    * `null` if any element in the input array is `null` but no element in the input array is `missing`,
-    * any other non-array input value or non-integer element in the input array will cause a type error.
-
- * Example:
-
-        codepoint_to_string([72, 101, 108, 108, 111, 32, 65, 83, 84, 69, 82, 73, 88, 33]);
-
-
- * The expected result is:
-
-        "Hello ASTERIX!"
-
-
-
 ### substr ###
  * Syntax:
 
@@ -598,57 +492,6 @@
         "str"
 
 
-### substring_before ###
- * Syntax:
-
-        substring_before(string, string_pattern)
-
- * Returns the substring from the given string `string` before the given pattern `string_pattern`.
- * Arguments:
-    * `string` : a `string` to be extracted.
-    * `string_pattern` : a `string` pattern to be searched.
- * Return Value:
-    * a `string` that represents the substring,
-    * `missing` if any argument is a `missing` value,
-    * `null` if any argument is a `null` value but no argument is a `missing` value,
-    * any other non-string input value will cause a type error.
-
- * Example:
-
-        substring_before(" like x-phone", "x-phone");
-
-
- * The expected result is:
-
-        " like "
-
-
-### substring_after ###
- * Syntax:
-
-       substring_after(string, string_pattern);
-
- * Returns the substring from the given string `string` after the given pattern `string_pattern`.
- * Arguments:
-    * `string` : a `string` to be extracted.
-    * `string_pattern` : a `string` pattern to be searched.
- * Return Value:
-    * a `string` that represents the substring,
-    * `missing` if any argument is a `missing` value,
-    * `null` if any argument is a `null` value but no argument is a `missing` value,
-    * any other non-string input value will cause a type error.
-
-
- * Example:
-
-        substring_after(" like x-phone", "xph");
-
-
- * The expected result is:
-
-        "one"
-
-
 ### trim ###
  * Syntax:
 
diff --git a/asterixdb/asterix-doc/src/main/markdown/builtins/2_string_delta.md b/asterixdb/asterix-doc/src/main/markdown/builtins/2_string_delta.md
new file mode 100644
index 0000000..fcf1c20
--- /dev/null
+++ b/asterixdb/asterix-doc/src/main/markdown/builtins/2_string_delta.md
@@ -0,0 +1,174 @@
+<!--
+ ! 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.
+ !-->
+
+### string_concat ###
+ * Syntax:
+
+        string_concat(array)
+
+ * Concatenates an array of strings `array` into a single string.
+ * Arguments:
+    * `array` : an `array` or `multiset` of `string`s (could be `null` or `missing`) to be concatenated.
+ * Return Value:
+    * the concatenated `string` value,
+    * `missing` if the argument is a `missing` value,
+    * `null` if any argument is a `null` value but no argument is a `missing` value,
+    * `missing` if any element in the input array is `missing`,
+    * `null` if any element in the input array is `null` but no element in the input array is `missing`,
+    * any other non-array input value or non-integer element in the input array will cause a type error.
+
+ * Example:
+
+        string_concat(["ASTERIX", " ", "ROCKS!"]);
+
+
+ * The expected result is:
+
+        "ASTERIX ROCKS!"
+
+
+### string_join ###
+ * Syntax:
+
+        string_join(array, string)
+
+ * Joins an array or multiset of strings `array` with the given separator `string` into a single string.
+ * Arguments:
+    * `array` : an `array` or `multiset` of strings (could be `null`) to be joined.
+    * `string` : a `string` to serve as the separator.
+ * Return Value:
+    * the joined `string`,
+    * `missing` if any argument is a `missing` value,
+    * `null` if any argument is a `null` value but no argument is a `missing` value,
+    * `missing` if the first argument array contains a `missing`,
+    * `null` if the first argument array contains a `null` but does not contain a `missing`,
+    * a type error will be raised if:
+        * the first argument is any other non-array value, or contains any other non-string value,
+        * or, the second argument is any other non-string value.
+
+ * Example:
+
+        string_join(["ASTERIX", "ROCKS~"], "!! ");
+
+
+ * The expected result is:
+
+        "ASTERIX!! ROCKS~"
+
+
+### string_to_codepoint ###
+ * Syntax:
+
+        string_to_codepoint(string)
+
+ * Converts the string `string` to its code_based representation.
+ * Arguments:
+    * `string` : a `string` that will be converted.
+ * Return Value:
+    * an `array` of the code points for the string `string`,
+    * `missing` if the argument is a `missing` value,
+    * `null` if the argument is a `null` value,
+    * any other non-string input value will cause a type error.
+
+ * Example:
+
+        string_to_codepoint("Hello ASTERIX!");
+
+
+ * The expected result is:
+
+        [ 72, 101, 108, 108, 111, 32, 65, 83, 84, 69, 82, 73, 88, 33 ]
+
+
+### codepoint_to_string ###
+ * Syntax:
+
+        codepoint_to_string(array)
+
+ * Converts the ordered code_based representation `array` to the corresponding string.
+ * Arguments:
+    * `array` : an `array` of integer code_points.
+ * Return Value:
+    * a `string` representation of `array`.
+    * `missing` if the argument is a `missing` value,
+    * `null` if the argument is a `null` value,
+    * `missing` if any element in the input array is `missing`,
+    * `null` if any element in the input array is `null` but no element in the input array is `missing`,
+    * any other non-array input value or non-integer element in the input array will cause a type error.
+
+ * Example:
+
+        codepoint_to_string([72, 101, 108, 108, 111, 32, 65, 83, 84, 69, 82, 73, 88, 33]);
+
+
+ * The expected result is:
+
+        "Hello ASTERIX!"
+
+
+### substring_before ###
+ * Syntax:
+
+        substring_before(string, string_pattern)
+
+ * Returns the substring from the given string `string` before the given pattern `string_pattern`.
+ * Arguments:
+    * `string` : a `string` to be extracted.
+    * `string_pattern` : a `string` pattern to be searched.
+ * Return Value:
+    * a `string` that represents the substring,
+    * `missing` if any argument is a `missing` value,
+    * `null` if any argument is a `null` value but no argument is a `missing` value,
+    * any other non-string input value will cause a type error.
+
+ * Example:
+
+        substring_before(" like x-phone", "x-phone");
+
+
+ * The expected result is:
+
+        " like "
+
+
+### substring_after ###
+ * Syntax:
+
+       substring_after(string, string_pattern);
+
+ * Returns the substring from the given string `string` after the given pattern `string_pattern`.
+ * Arguments:
+    * `string` : a `string` to be extracted.
+    * `string_pattern` : a `string` pattern to be searched.
+ * Return Value:
+    * a `string` that represents the substring,
+    * `missing` if any argument is a `missing` value,
+    * `null` if any argument is a `null` value but no argument is a `missing` value,
+    * any other non-string input value will cause a type error.
+
+
+ * Example:
+
+        substring_after(" like x-phone", "xph");
+
+
+ * The expected result is:
+
+        "one"
+
diff --git a/asterixdb/asterix-runtime/src/main/java/org/apache/asterix/runtime/evaluators/functions/StringPositionDescriptor.java b/asterixdb/asterix-runtime/src/main/java/org/apache/asterix/runtime/evaluators/functions/StringPositionDescriptor.java
index 523207c..6f4d116 100644
--- a/asterixdb/asterix-runtime/src/main/java/org/apache/asterix/runtime/evaluators/functions/StringPositionDescriptor.java
+++ b/asterixdb/asterix-runtime/src/main/java/org/apache/asterix/runtime/evaluators/functions/StringPositionDescriptor.java
@@ -54,7 +54,8 @@
 
                     @Override
                     protected int compute(UTF8StringPointable left, UTF8StringPointable right) throws IOException {
-                        return UTF8StringPointable.find(left, right, false);
+                        int pos = UTF8StringPointable.find(left, right, false);
+                        return pos < 0 ? pos : pos + 1;
                     }
                 };
             }
diff --git a/asterixdb/asterix-runtime/src/main/java/org/apache/asterix/runtime/evaluators/functions/StringRegExpPositionDescriptor.java b/asterixdb/asterix-runtime/src/main/java/org/apache/asterix/runtime/evaluators/functions/StringRegExpPositionDescriptor.java
index a41fb56..1bb0fdc 100644
--- a/asterixdb/asterix-runtime/src/main/java/org/apache/asterix/runtime/evaluators/functions/StringRegExpPositionDescriptor.java
+++ b/asterixdb/asterix-runtime/src/main/java/org/apache/asterix/runtime/evaluators/functions/StringRegExpPositionDescriptor.java
@@ -58,7 +58,8 @@
                     protected int compute(UTF8StringPointable srcPtr, UTF8StringPointable patternPtr)
                             throws IOException {
                         matcher.build(srcPtr, patternPtr);
-                        return matcher.postion();
+                        int pos = matcher.postion();
+                        return pos < 0 ? pos : pos + 1;
                     }
                 };
             }
diff --git a/asterixdb/asterix-runtime/src/main/java/org/apache/asterix/runtime/evaluators/functions/StringRegExpPositionWithFlagDescriptor.java b/asterixdb/asterix-runtime/src/main/java/org/apache/asterix/runtime/evaluators/functions/StringRegExpPositionWithFlagDescriptor.java
index ea04896..35eb3b1 100644
--- a/asterixdb/asterix-runtime/src/main/java/org/apache/asterix/runtime/evaluators/functions/StringRegExpPositionWithFlagDescriptor.java
+++ b/asterixdb/asterix-runtime/src/main/java/org/apache/asterix/runtime/evaluators/functions/StringRegExpPositionWithFlagDescriptor.java
@@ -58,7 +58,8 @@
                     protected int compute(UTF8StringPointable srcPtr, UTF8StringPointable patternPtr,
                             UTF8StringPointable flagPtr) throws IOException {
                         matcher.build(srcPtr, patternPtr, flagPtr);
-                        return matcher.postion();
+                        int pos = matcher.postion();
+                        return pos < 0 ? pos : pos + 1;
                     }
                 };
             }