diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/string/substring_multi_codepoint_01/substring_multi_codepoint_01.1.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/string/substring_multi_codepoint_01/substring_multi_codepoint_01.1.query.sqlpp
new file mode 100644
index 0000000..16e75a4
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/string/substring_multi_codepoint_01/substring_multi_codepoint_01.1.query.sqlpp
@@ -0,0 +1,24 @@
+/*
+ * 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.
+ */
+
+{
+  '2 people in a 4-people family': SUBSTR("👨‍👨‍👦‍👦", 2, 3),
+  'Korean test 0': SUBSTR('한글', 3,3),
+  'Korean test 1': SUBSTR('한글', 2,2)
+};
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/string/substring_multi_codepoint_01/substring_multi_codepoint_01.1.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/string/substring_multi_codepoint_01/substring_multi_codepoint_01.1.adm
new file mode 100644
index 0000000..5157e8a
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/string/substring_multi_codepoint_01/substring_multi_codepoint_01.1.adm
@@ -0,0 +1 @@
+{ "2 people in a 4-people family": "👨‍👦", "Korean test 0": "글", "Korean test 1": "ᆫᄀ" }
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 1e11bb8..8f9e1e8 100644
--- a/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml
@@ -9908,6 +9908,11 @@
       </compilation-unit>
     </test-case>
     <test-case FilePath="string">
+      <compilation-unit name="substring_multi_codepoint_01">
+        <output-dir compare="Text">substring_multi_codepoint_01</output-dir>
+      </compilation-unit>
+    </test-case>
+    <test-case FilePath="string">
       <compilation-unit name="substring-after-1">
         <output-dir compare="Text">substring-after-1</output-dir>
       </compilation-unit>
diff --git a/asterixdb/asterix-doc/src/main/markdown/builtins/2_string_common.md b/asterixdb/asterix-doc/src/main/markdown/builtins/2_string_common.md
index 58d0e10..528ff5d 100644
--- a/asterixdb/asterix-doc/src/main/markdown/builtins/2_string_common.md
+++ b/asterixdb/asterix-doc/src/main/markdown/builtins/2_string_common.md
@@ -554,6 +554,8 @@
         substr(string, offset[, length])
 
  * Returns the substring from the given string `string` based on the given start offset `offset` with the optional `length`. 
+ Note that both of the `offset` and `length` are in the unit of code point
+ (e.g. the emoji family 👨‍👩‍👧‍👦 has 7 code points).
  The function uses the 0-based position. Another version of the function uses the 1-based position. Below are the
  aliases for each version:
 
diff --git a/hyracks-fullstack/hyracks/hyracks-data/hyracks-data-std/src/main/java/org/apache/hyracks/data/std/primitive/UTF8StringPointable.java b/hyracks-fullstack/hyracks/hyracks-data/hyracks-data-std/src/main/java/org/apache/hyracks/data/std/primitive/UTF8StringPointable.java
index 9ff2f41..944b317 100644
--- a/hyracks-fullstack/hyracks/hyracks-data/hyracks-data-std/src/main/java/org/apache/hyracks/data/std/primitive/UTF8StringPointable.java
+++ b/hyracks-fullstack/hyracks/hyracks-data/hyracks-data-std/src/main/java/org/apache/hyracks/data/std/primitive/UTF8StringPointable.java
@@ -114,6 +114,14 @@
         return UTF8StringUtil.charSize(bytes, start + offset);
     }
 
+    public int codePointAt(int offset) {
+        return UTF8StringUtil.codePointAt(bytes, start + offset);
+    }
+
+    public int codePointSize(int offset) {
+        return UTF8StringUtil.codePointSize(bytes, start + offset);
+    }
+
     /**
      * Gets the length of the string in characters.
      * The first time call will need to go through the entire string, the following call will just return the pre-caculated result
@@ -337,43 +345,45 @@
     }
 
     /**
+     * Return the substring. Note that the offset and length are in the unit of code point.
      * @return {@code true} if substring was successfully written into given {@code out}, or
-     *         {@code false} if substring could not be obtained ({@code charOffset} or {@code charLength}
+     *         {@code false} if substring could not be obtained ({@code codePointOffset} or {@code codePointLength}
      *         are less than 0 or starting position is greater than the input length)
      */
-    public boolean substr(int charOffset, int charLength, UTF8StringBuilder builder, GrowableArray out)
+    public boolean substr(int codePointOffset, int codePointLength, UTF8StringBuilder builder, GrowableArray out)
             throws IOException {
-        return substr(this, charOffset, charLength, builder, out);
+        return substr(this, codePointOffset, codePointLength, builder, out);
     }
 
     /**
+     * Return the substring. Note that the offset and length are in the unit of code point.
      * @return {@code true} if substring was successfully written into given {@code out}, or
-     *         {@code false} if substring could not be obtained ({@code charOffset} or {@code charLength}
+     *         {@code false} if substring could not be obtained ({@code codePointOffset} or {@code codePointLength}
      *         are less than 0 or starting position is greater than the input length)
      */
-    public static boolean substr(UTF8StringPointable src, int charOffset, int charLength, UTF8StringBuilder builder,
-            GrowableArray out) throws IOException {
-        if (charOffset < 0 || charLength < 0) {
+    public static boolean substr(UTF8StringPointable src, int codePointOffset, int codePointLength,
+            UTF8StringBuilder builder, GrowableArray out) throws IOException {
+        if (codePointOffset < 0 || codePointLength < 0) {
             return false;
         }
 
         int utfLen = src.getUTF8Length();
-        int chIdx = 0;
+        int codePointIdx = 0;
         int byteIdx = 0;
-        while (byteIdx < utfLen && chIdx < charOffset) {
-            byteIdx += src.charSize(src.getMetaDataLength() + byteIdx);
-            chIdx++;
+        while (byteIdx < utfLen && codePointIdx < codePointOffset) {
+            byteIdx += src.codePointSize(src.getMetaDataLength() + byteIdx);
+            codePointIdx++;
         }
         if (byteIdx >= utfLen) {
             return false;
         }
 
-        builder.reset(out, Math.min(utfLen - byteIdx, (int) (charLength * 1.0 * byteIdx / chIdx)));
-        chIdx = 0;
-        while (byteIdx < utfLen && chIdx < charLength) {
-            builder.appendChar(src.charAt(src.getMetaDataLength() + byteIdx));
-            chIdx++;
-            byteIdx += src.charSize(src.getMetaDataLength() + byteIdx);
+        builder.reset(out, Math.min(utfLen - byteIdx, (int) (codePointLength * 1.0 * byteIdx / codePointIdx)));
+        codePointIdx = 0;
+        while (byteIdx < utfLen && codePointIdx < codePointLength) {
+            builder.appendCodePoint(src.codePointAt(src.getMetaDataLength() + byteIdx));
+            codePointIdx++;
+            byteIdx += src.codePointSize(src.getMetaDataLength() + byteIdx);
         }
         builder.finish();
         return true;
diff --git a/hyracks-fullstack/hyracks/hyracks-data/hyracks-data-std/src/main/java/org/apache/hyracks/data/std/util/UTF8StringBuilder.java b/hyracks-fullstack/hyracks/hyracks-data/hyracks-data-std/src/main/java/org/apache/hyracks/data/std/util/UTF8StringBuilder.java
index 2300c06..147ac86 100644
--- a/hyracks-fullstack/hyracks/hyracks-data/hyracks-data-std/src/main/java/org/apache/hyracks/data/std/util/UTF8StringBuilder.java
+++ b/hyracks-fullstack/hyracks/hyracks-data/hyracks-data-std/src/main/java/org/apache/hyracks/data/std/util/UTF8StringBuilder.java
@@ -23,10 +23,19 @@
 
 public class UTF8StringBuilder extends AbstractVarLenObjectBuilder {
 
+    private final char[] tmpCharsForCodePointConversion = new char[2];
+
     public void appendChar(char ch) throws IOException {
         UTF8StringUtil.writeCharAsModifiedUTF8(ch, out);
     }
 
+    public void appendCodePoint(int codePoint) throws IOException {
+        int numChar = Character.toChars(codePoint, tmpCharsForCodePointConversion, 0);
+        for (int i = 0; i < numChar; i++) {
+            appendChar(tmpCharsForCodePointConversion[i]);
+        }
+    }
+
     public void appendString(String string) throws IOException {
         for (int i = 0; i < string.length(); i++) {
             appendChar(string.charAt(i));
diff --git a/hyracks-fullstack/hyracks/hyracks-data/hyracks-data-std/src/test/java/org/apache/hyracks/data/std/primitive/UTF8StringPointableTest.java b/hyracks-fullstack/hyracks/hyracks-data/hyracks-data-std/src/test/java/org/apache/hyracks/data/std/primitive/UTF8StringPointableTest.java
index 302e7a0..fa93003 100644
--- a/hyracks-fullstack/hyracks/hyracks-data/hyracks-data-std/src/test/java/org/apache/hyracks/data/std/primitive/UTF8StringPointableTest.java
+++ b/hyracks-fullstack/hyracks/hyracks-data/hyracks-data-std/src/test/java/org/apache/hyracks/data/std/primitive/UTF8StringPointableTest.java
@@ -20,10 +20,14 @@
 package org.apache.hyracks.data.std.primitive;
 
 import static org.apache.hyracks.data.std.primitive.UTF8StringPointable.generateUTF8Pointable;
+import static org.apache.hyracks.util.string.UTF8StringSample.STRING_EMOJI_FAMILY_OF_2;
+import static org.apache.hyracks.util.string.UTF8StringSample.STRING_EMOJI_FAMILY_OF_4;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
+import java.io.IOException;
+
 import org.apache.commons.lang3.CharSet;
 import org.apache.hyracks.data.std.util.GrowableArray;
 import org.apache.hyracks.data.std.util.UTF8StringBuilder;
@@ -40,6 +44,11 @@
     public static UTF8StringPointable STRING_LEN_127 = generateUTF8Pointable(UTF8StringSample.STRING_LEN_127);
     public static UTF8StringPointable STRING_LEN_128 = generateUTF8Pointable(UTF8StringSample.STRING_LEN_128);
 
+    public static UTF8StringPointable STRING_POINTABLE_EMOJI_FAMILY_OF_4 =
+            generateUTF8Pointable(STRING_EMOJI_FAMILY_OF_4);
+    public static UTF8StringPointable STRING_POINTABLE_EMOJI_FAMILY_OF_2 =
+            generateUTF8Pointable(STRING_EMOJI_FAMILY_OF_2);
+
     @Test
     public void testGetStringLength() throws Exception {
         UTF8StringPointable utf8Ptr = generateUTF8Pointable(UTF8StringSample.STRING_LEN_127);
@@ -119,6 +128,19 @@
     }
 
     @Test
+    public void testSubstrWithMultiCodePointCharacter() throws IOException {
+        GrowableArray storage = new GrowableArray();
+        UTF8StringBuilder builder = new UTF8StringBuilder();
+
+        // The middle 2 people of the 4-people-family is a 2-people-family
+        STRING_POINTABLE_EMOJI_FAMILY_OF_4.substr(2, 3, builder, storage);
+        UTF8StringPointable result = new UTF8StringPointable();
+        result.set(storage.getByteArray(), 0, storage.getLength());
+
+        assertEquals(0, STRING_POINTABLE_EMOJI_FAMILY_OF_2.compareTo(result));
+    }
+
+    @Test
     public void testSubstrBefore() throws Exception {
         UTF8StringBuilder builder = new UTF8StringBuilder();
         GrowableArray storage = new GrowableArray();
diff --git a/hyracks-fullstack/hyracks/hyracks-util/src/main/java/org/apache/hyracks/util/string/UTF8StringUtil.java b/hyracks-fullstack/hyracks/hyracks-util/src/main/java/org/apache/hyracks/util/string/UTF8StringUtil.java
index 2b0e49e..c3ee97c 100644
--- a/hyracks-fullstack/hyracks/hyracks-util/src/main/java/org/apache/hyracks/util/string/UTF8StringUtil.java
+++ b/hyracks-fullstack/hyracks/hyracks-util/src/main/java/org/apache/hyracks/util/string/UTF8StringUtil.java
@@ -90,6 +90,50 @@
         }
     }
 
+    public static int codePointAt(byte[] b, int s) {
+        char c1 = charAt(b, s);
+
+        if (Character.isLowSurrogate(c1)) {
+            // In this case, the index s doesn't point to a correct position
+            throw new IllegalArgumentException("decoding error: got a low surrogate without a high surrogate");
+        }
+
+        if (Character.isHighSurrogate(c1)) {
+            // If c1 is the a high surrogate and also the last char in the byte array (that means the byte array is somehow illegal),
+            // then an exception will be thrown because there is no low surrogate (c2) available in the byte array
+            s += charSize(b, s);
+            char c2 = charAt(b, s);
+            if (Character.isLowSurrogate(c2)) {
+                return Character.toCodePoint(c1, c2);
+            } else {
+                throw new IllegalArgumentException(
+                        "decoding error: the high surrogate is not followed by a low surrogate");
+            }
+        }
+
+        return c1;
+    }
+
+    public static int codePointSize(byte[] b, int s) {
+        char c1 = charAt(b, s);
+        int size1 = charSize(b, s);
+
+        if (Character.isLowSurrogate(c1)) {
+            throw new IllegalArgumentException("decoding error: got a low surrogate without a high surrogate");
+        }
+
+        if (Character.isHighSurrogate(c1)) {
+            // Similar to the above codePointAt(),
+            // if c1 is the a high surrogate and also the last char in the byte array (that means the byte array is somehow illegal),
+            // then an exception will be thrown because there is no low surrogate available in the byte array
+            s += charSize(b, s);
+            int size2 = charSize(b, s);
+            return size1 + size2;
+        }
+
+        return size1;
+    }
+
     public static boolean isCharStart(byte[] b, int s) {
         int c = b[s] & 0xff;
         return (c >> 6) != 2;
diff --git a/hyracks-fullstack/hyracks/hyracks-util/src/test/java/org/apache/hyracks/util/string/UTF8StringSample.java b/hyracks-fullstack/hyracks/hyracks-util/src/test/java/org/apache/hyracks/util/string/UTF8StringSample.java
index 6984d75..1502f25 100644
--- a/hyracks-fullstack/hyracks/hyracks-util/src/test/java/org/apache/hyracks/util/string/UTF8StringSample.java
+++ b/hyracks-fullstack/hyracks/hyracks-util/src/test/java/org/apache/hyracks/util/string/UTF8StringSample.java
@@ -39,6 +39,9 @@
     public static final String STRING_UTF8_MIX_LOWERCASE = "\uD841\uDF0E\uD841\uDF31锟x斤y拷zà";
     public static final String STRING_NEEDS_2_JAVA_CHARS_1 = "\uD83D\uDE22\uD83D\uDE22\uD83D\uDC89\uD83D\uDC89";
     public static final String STRING_NEEDS_2_JAVA_CHARS_2 = "😢😢💉💉";
+    public static final String STRING_EMOJI_FAMILY_OF_4 =
+            "\uD83D\uDC68\u200D\uD83D\uDC68\u200D\uD83D\uDC66\u200D\uD83D\uDC66";
+    public static final String STRING_EMOJI_FAMILY_OF_2 = "\uD83D\uDC68\u200D\uD83D\uDC66";
 
     public static final String STRING_LEN_127 = generateStringRepeatBy(ONE_ASCII_CHAR, 127);
     public static final String STRING_LEN_128 = generateStringRepeatBy(ONE_ASCII_CHAR, 128);