diff --git a/docs/content/querying/dimensionspecs.md b/docs/content/querying/dimensionspecs.md
index 8879290db43..26160373a24 100644
--- a/docs/content/querying/dimensionspecs.md
+++ b/docs/content/querying/dimensionspecs.md
@@ -341,6 +341,16 @@ Example for chaining [regular expression extraction function](#regular-expressio
 It will transform dimension values with specified extraction functions in the order named.
 For example, `'/druid/prod/historical'` is transformed to `'the dru'` as regular expression extraction function first transforms it to `'druid'` and then, javascript extraction function transforms it to `'the druid'`, and lastly, substring extraction function transforms it to `'the dru'`. 
 
+### String Format Extraction Function
+
+Returns the dimension value formatted according to the given format string.
+
+```json
+{ "type" : "stringFormat", "format" : <sprintf_expression> }
+```
+
+For example if you want to concat "[" and "]" before and after the actual dimension value, you need to specify "[%s]" as format string.
+
 ### Filtering DimensionSpecs
 
 These are only valid for multi-valued dimensions. If you have a row in druid that has a multi-valued dimension with values ["v1", "v2", "v3"] and you send a groupBy/topN query grouping by that dimension with [query filter](filter.html) for value "v1". In the response you will get 3 rows containing "v1", "v2" and "v3". This behavior might be unintuitive for some use cases.
diff --git a/processing/src/main/java/io/druid/query/extraction/CascadeExtractionFn.java b/processing/src/main/java/io/druid/query/extraction/CascadeExtractionFn.java
index a7dc5d13f6e..b3d09805ca1 100644
--- a/processing/src/main/java/io/druid/query/extraction/CascadeExtractionFn.java
+++ b/processing/src/main/java/io/druid/query/extraction/CascadeExtractionFn.java
@@ -29,38 +29,44 @@ import java.util.Arrays;
 
 public class CascadeExtractionFn implements ExtractionFn
 {
-  private static final byte CACHE_TYPE_ID = 0x9;
-
   private final ExtractionFn extractionFns[];
   private final ChainedExtractionFn chainedExtractionFn;
   private final ChainedExtractionFn DEFAULT_CHAINED_EXTRACTION_FN = new ChainedExtractionFn(
-      new ExtractionFn() {
-        public byte[] getCacheKey() {
+      new ExtractionFn()
+      {
+        public byte[] getCacheKey()
+        {
           return new byte[0];
         }
 
-        public String apply(Object value) {
+        public String apply(Object value)
+        {
           return null;
         }
 
-        public String apply(String value) {
+        public String apply(String value)
+        {
           return null;
         }
 
-        public String apply(long value) {
+        public String apply(long value)
+        {
           return null;
         }
 
-        public boolean preservesOrdering() {
+        public boolean preservesOrdering()
+        {
           return false;
         }
 
-        public ExtractionType getExtractionType() {
+        public ExtractionType getExtractionType()
+        {
           return ExtractionType.MANY_TO_ONE;
         }
 
         @Override
-        public String toString() {
+        public String toString()
+        {
           return "nullExtractionFn{}";
         }
       },
@@ -78,48 +84,55 @@ public class CascadeExtractionFn implements ExtractionFn
       this.chainedExtractionFn = DEFAULT_CHAINED_EXTRACTION_FN;
     } else {
       ChainedExtractionFn root = null;
-      for (int idx = 0; idx < extractionFns.length; idx++) {
-        Preconditions.checkArgument(extractionFns[idx] != null, "empty function is not allowed");
-        root = new ChainedExtractionFn(extractionFns[idx], root);
+      for (ExtractionFn fn : extractionFn) {
+        Preconditions.checkArgument(fn != null, "empty function is not allowed");
+        root = new ChainedExtractionFn(fn, root);
       }
       this.chainedExtractionFn = root;
     }
   }
 
   @JsonProperty
-  public ExtractionFn[] getExtractionFns() {
+  public ExtractionFn[] getExtractionFns()
+  {
     return extractionFns;
   }
 
   @Override
-  public byte[] getCacheKey() {
-    byte[] cacheKey = new byte[] {CACHE_TYPE_ID};
+  public byte[] getCacheKey()
+  {
+    byte[] cacheKey = new byte[]{ExtractionCacheHelper.CACHE_TYPE_ID_CASCADE};
 
     return Bytes.concat(cacheKey, chainedExtractionFn.getCacheKey());
   }
 
   @Override
-  public String apply(Object value) {
+  public String apply(Object value)
+  {
     return chainedExtractionFn.apply(value);
   }
 
   @Override
-  public String apply(String value){
+  public String apply(String value)
+  {
     return chainedExtractionFn.apply(value);
   }
 
   @Override
-  public String apply(long value){
+  public String apply(long value)
+  {
     return chainedExtractionFn.apply(value);
   }
 
   @Override
-  public boolean preservesOrdering(){
+  public boolean preservesOrdering()
+  {
     return chainedExtractionFn.preservesOrdering();
   }
 
   @Override
-  public ExtractionType getExtractionType(){
+  public ExtractionType getExtractionType()
+  {
     return chainedExtractionFn.getExtractionType();
   }
 
@@ -152,44 +165,53 @@ public class CascadeExtractionFn implements ExtractionFn
   }
 
   @Override
-  public String toString() {
+  public String toString()
+  {
     return "CascadeExtractionFn{" +
-        "extractionFns=[" + chainedExtractionFn.toString() + "]}";
+           "extractionFns=[" + chainedExtractionFn.toString() + "]}";
   }
 
-  private class ChainedExtractionFn {
+  private class ChainedExtractionFn
+  {
     private final ExtractionFn fn;
     private final ChainedExtractionFn child;
 
-    public ChainedExtractionFn(ExtractionFn fn, ChainedExtractionFn child) {
+    public ChainedExtractionFn(ExtractionFn fn, ChainedExtractionFn child)
+    {
       this.fn = fn;
       this.child = child;
     }
 
-    public byte[] getCacheKey() {
+    public byte[] getCacheKey()
+    {
       byte[] fnCacheKey = fn.getCacheKey();
 
       return (child != null) ? Bytes.concat(fnCacheKey, child.getCacheKey()) : fnCacheKey;
     }
 
-    public String apply(Object value) {
+    public String apply(Object value)
+    {
       return fn.apply((child != null) ? child.apply(value) : value);
     }
 
-    public String apply(String value){
+    public String apply(String value)
+    {
       return fn.apply((child != null) ? child.apply(value) : value);
     }
 
-    public String apply(long value){
+    public String apply(long value)
+    {
       return fn.apply((child != null) ? child.apply(value) : value);
     }
 
-    public boolean preservesOrdering(){
+    public boolean preservesOrdering()
+    {
       boolean childPreservesOrdering = (child == null) || child.preservesOrdering();
       return fn.preservesOrdering() && childPreservesOrdering;
     }
 
-    public ExtractionType getExtractionType(){
+    public ExtractionType getExtractionType()
+    {
       if (child != null && child.getExtractionType() == ExtractionType.MANY_TO_ONE) {
         return ExtractionType.MANY_TO_ONE;
       } else {
@@ -227,10 +249,11 @@ public class CascadeExtractionFn implements ExtractionFn
       return result;
     }
 
-    public String toString() {
+    public String toString()
+    {
       return (child != null)
-          ? Joiner.on(",").join(child.toString(), fn.toString())
-          : fn.toString();
+             ? Joiner.on(",").join(child.toString(), fn.toString())
+             : fn.toString();
     }
   }
 }
diff --git a/processing/src/main/java/io/druid/query/extraction/DimExtractionFn.java b/processing/src/main/java/io/druid/query/extraction/DimExtractionFn.java
index f3127afd8ae..afb22cd567b 100644
--- a/processing/src/main/java/io/druid/query/extraction/DimExtractionFn.java
+++ b/processing/src/main/java/io/druid/query/extraction/DimExtractionFn.java
@@ -24,7 +24,7 @@ public abstract class DimExtractionFn implements ExtractionFn
   @Override
   public String apply(Object value)
   {
-    return apply(value.toString());
+    return apply(value == null ? null : value.toString());
   }
 
   @Override
diff --git a/processing/src/main/java/io/druid/query/extraction/ExtractionCacheHelper.java b/processing/src/main/java/io/druid/query/extraction/ExtractionCacheHelper.java
new file mode 100644
index 00000000000..3a5b8c5d88f
--- /dev/null
+++ b/processing/src/main/java/io/druid/query/extraction/ExtractionCacheHelper.java
@@ -0,0 +1,38 @@
+/*
+* Licensed to Metamarkets Group Inc. (Metamarkets) under one
+* or more contributor license agreements. See the NOTICE file
+* distributed with this work for additional information
+* regarding copyright ownership. Metamarkets 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.
+*/
+
+package io.druid.query.extraction;
+
+/**
+ *
+ */
+public class ExtractionCacheHelper
+{
+  public static final byte CACHE_TYPE_ID_TIME_DIM = 0x0;
+  public static final byte CACHE_TYPE_ID_REGEX = 0x1;
+  public static final byte CACHE_TYPE_ID_MATCHING_DIM = 0x2;
+  public static final byte CACHE_TYPE_ID_SEARCH_QUERY = 0x3;
+  public static final byte CACHE_TYPE_ID_JAVASCRIPT = 0x4;
+  public static final byte CACHE_TYPE_ID_TIME_FORMAT = 0x5;
+  public static final byte CACHE_TYPE_ID_IDENTITY = 0x6;
+  public static final byte CACHE_TYPE_ID_LOOKUP = 0x7;
+  public static final byte CACHE_TYPE_ID_SUBSTRING = 0x8;
+  public static final byte CACHE_TYPE_ID_CASCADE = 0x9;
+  public static final byte CACHE_TYPE_ID_STRING_FORMAT = 0xA;
+}
diff --git a/processing/src/main/java/io/druid/query/extraction/ExtractionFn.java b/processing/src/main/java/io/druid/query/extraction/ExtractionFn.java
index 800bc8e4054..6361ca90bad 100644
--- a/processing/src/main/java/io/druid/query/extraction/ExtractionFn.java
+++ b/processing/src/main/java/io/druid/query/extraction/ExtractionFn.java
@@ -35,7 +35,8 @@ import com.fasterxml.jackson.annotation.JsonTypeInfo;
     @JsonSubTypes.Type(name = "identity", value = IdentityExtractionFn.class),
     @JsonSubTypes.Type(name = "lookup", value = LookupExtractionFn.class),
     @JsonSubTypes.Type(name = "substring", value = SubstringDimExtractionFn.class),
-    @JsonSubTypes.Type(name = "cascade", value = CascadeExtractionFn.class)
+    @JsonSubTypes.Type(name = "cascade", value = CascadeExtractionFn.class),
+    @JsonSubTypes.Type(name = "stringFormat", value = StringFormatExtractionFn.class)
 })
 /**
  * An ExtractionFn is a function that can be used to transform the values of a column (typically a dimension)
@@ -56,7 +57,7 @@ public interface ExtractionFn
 
   /**
    * The "extraction" function.  This should map a value into some other String value.
-   *
+   * <p>
    * In order to maintain the "null and empty string are equivalent" semantics that Druid provides, the
    * empty string is considered invalid output for this method and should instead return null.  This is
    * a contract on the method rather than enforced at a lower level in order to eliminate a global check
@@ -74,7 +75,7 @@ public interface ExtractionFn
 
   /**
    * Offers information on whether the extraction will preserve the original ordering of the values.
-   * <p/>
+   * <p>
    * Some optimizations of queries is possible if ordering is preserved.  Null values *do* count towards
    * ordering.
    *
diff --git a/processing/src/main/java/io/druid/query/extraction/IdentityExtractionFn.java b/processing/src/main/java/io/druid/query/extraction/IdentityExtractionFn.java
index 76a71977084..9d9153efabd 100644
--- a/processing/src/main/java/io/druid/query/extraction/IdentityExtractionFn.java
+++ b/processing/src/main/java/io/druid/query/extraction/IdentityExtractionFn.java
@@ -23,8 +23,6 @@ import com.google.common.base.Strings;
 
 public class IdentityExtractionFn implements ExtractionFn
 {
-  private static final byte CACHE_TYPE_ID = 0x6;
-
   private static final IdentityExtractionFn instance = new IdentityExtractionFn();
 
   private IdentityExtractionFn()
@@ -35,7 +33,7 @@ public class IdentityExtractionFn implements ExtractionFn
   @Override
   public byte[] getCacheKey()
   {
-    return new byte[]{CACHE_TYPE_ID};
+    return new byte[]{ExtractionCacheHelper.CACHE_TYPE_ID_IDENTITY};
   }
 
   @Override
@@ -67,13 +65,13 @@ public class IdentityExtractionFn implements ExtractionFn
   {
     return ExtractionType.ONE_TO_ONE;
   }
-  
+
   @Override
   public String toString()
   {
      return "Identity";
   }
-  
+
   @Override
   public boolean equals(Object o)
   {
diff --git a/processing/src/main/java/io/druid/query/extraction/JavaScriptExtractionFn.java b/processing/src/main/java/io/druid/query/extraction/JavaScriptExtractionFn.java
index 4830abb58eb..0263ddc10aa 100644
--- a/processing/src/main/java/io/druid/query/extraction/JavaScriptExtractionFn.java
+++ b/processing/src/main/java/io/druid/query/extraction/JavaScriptExtractionFn.java
@@ -61,8 +61,6 @@ public class JavaScriptExtractionFn implements ExtractionFn
     };
   }
 
-  private static final byte CACHE_TYPE_ID = 0x4;
-
   private final String function;
   private final Function<Object, String> fn;
   private final boolean injective;
@@ -97,7 +95,7 @@ public class JavaScriptExtractionFn implements ExtractionFn
   {
     byte[] bytes = StringUtils.toUtf8(function);
     return ByteBuffer.allocate(1 + bytes.length)
-                     .put(CACHE_TYPE_ID)
+                     .put(ExtractionCacheHelper.CACHE_TYPE_ID_JAVASCRIPT)
                      .put(bytes)
                      .array();
   }
diff --git a/processing/src/main/java/io/druid/query/extraction/LookupExtractionFn.java b/processing/src/main/java/io/druid/query/extraction/LookupExtractionFn.java
index 878ac6db2ac..d12b545116e 100644
--- a/processing/src/main/java/io/druid/query/extraction/LookupExtractionFn.java
+++ b/processing/src/main/java/io/druid/query/extraction/LookupExtractionFn.java
@@ -33,8 +33,6 @@ import java.io.IOException;
 
 public class LookupExtractionFn extends FunctionalExtraction
 {
-  private static final byte CACHE_TYPE_ID = 0x7;
-
   private final LookupExtractor lookup;
   private final boolean optimize;
 
@@ -98,7 +96,7 @@ public class LookupExtractionFn extends FunctionalExtraction
   {
     try {
       final ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
-      outputStream.write(CACHE_TYPE_ID);
+      outputStream.write(ExtractionCacheHelper.CACHE_TYPE_ID_LOOKUP);
       outputStream.write(lookup.getCacheKey());
       if (getReplaceMissingValueWith() != null) {
         outputStream.write(StringUtils.toUtf8(getReplaceMissingValueWith()));
diff --git a/processing/src/main/java/io/druid/query/extraction/MatchingDimExtractionFn.java b/processing/src/main/java/io/druid/query/extraction/MatchingDimExtractionFn.java
index 8c32f00a54e..c69edd58c63 100644
--- a/processing/src/main/java/io/druid/query/extraction/MatchingDimExtractionFn.java
+++ b/processing/src/main/java/io/druid/query/extraction/MatchingDimExtractionFn.java
@@ -32,8 +32,6 @@ import java.util.regex.Pattern;
  */
 public class MatchingDimExtractionFn extends DimExtractionFn
 {
-  private static final byte CACHE_TYPE_ID = 0x2;
-
   private final String expr;
   private final Pattern pattern;
 
@@ -53,7 +51,7 @@ public class MatchingDimExtractionFn extends DimExtractionFn
   {
     byte[] exprBytes = StringUtils.toUtf8(expr);
     return ByteBuffer.allocate(1 + exprBytes.length)
-                     .put(CACHE_TYPE_ID)
+                     .put(ExtractionCacheHelper.CACHE_TYPE_ID_MATCHING_DIM)
                      .put(exprBytes)
                      .array();
   }
diff --git a/processing/src/main/java/io/druid/query/extraction/RegexDimExtractionFn.java b/processing/src/main/java/io/druid/query/extraction/RegexDimExtractionFn.java
index b86c84a473d..e9f13e98919 100644
--- a/processing/src/main/java/io/druid/query/extraction/RegexDimExtractionFn.java
+++ b/processing/src/main/java/io/druid/query/extraction/RegexDimExtractionFn.java
@@ -33,7 +33,6 @@ import java.util.regex.Pattern;
  */
 public class RegexDimExtractionFn extends DimExtractionFn
 {
-  private static final byte CACHE_TYPE_ID = 0x1;
   private static final byte CACHE_KEY_SEPARATOR = (byte) 0xFF;
 
   private final String expr;
@@ -75,7 +74,7 @@ public class RegexDimExtractionFn extends DimExtractionFn
     totalLen += 2; // separators
 
     return ByteBuffer.allocate(totalLen)
-                     .put(CACHE_TYPE_ID)
+                     .put(ExtractionCacheHelper.CACHE_TYPE_ID_REGEX)
                      .put(exprBytes)
                      .put(CACHE_KEY_SEPARATOR)
                      .put(replaceStrBytes)
diff --git a/processing/src/main/java/io/druid/query/extraction/SearchQuerySpecDimExtractionFn.java b/processing/src/main/java/io/druid/query/extraction/SearchQuerySpecDimExtractionFn.java
index 9b925a6ae41..31f0ccabb62 100644
--- a/processing/src/main/java/io/druid/query/extraction/SearchQuerySpecDimExtractionFn.java
+++ b/processing/src/main/java/io/druid/query/extraction/SearchQuerySpecDimExtractionFn.java
@@ -30,8 +30,6 @@ import java.nio.ByteBuffer;
  */
 public class SearchQuerySpecDimExtractionFn extends DimExtractionFn
 {
-  private static final byte CACHE_TYPE_ID = 0x3;
-
   private final SearchQuerySpec searchQuerySpec;
 
   @JsonCreator
@@ -55,7 +53,7 @@ public class SearchQuerySpecDimExtractionFn extends DimExtractionFn
   {
     byte[] specBytes = searchQuerySpec.getCacheKey();
     return ByteBuffer.allocate(1 + specBytes.length)
-                     .put(CACHE_TYPE_ID)
+                     .put(ExtractionCacheHelper.CACHE_TYPE_ID_SEARCH_QUERY)
                      .put(specBytes)
                      .array();
   }
diff --git a/processing/src/main/java/io/druid/query/extraction/StringFormatExtractionFn.java b/processing/src/main/java/io/druid/query/extraction/StringFormatExtractionFn.java
new file mode 100644
index 00000000000..fcdf7e03d8c
--- /dev/null
+++ b/processing/src/main/java/io/druid/query/extraction/StringFormatExtractionFn.java
@@ -0,0 +1,101 @@
+/*
+* Licensed to Metamarkets Group Inc. (Metamarkets) under one
+* or more contributor license agreements. See the NOTICE file
+* distributed with this work for additional information
+* regarding copyright ownership. Metamarkets 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.
+*/
+
+package io.druid.query.extraction;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.google.common.base.Preconditions;
+import com.google.common.base.Strings;
+import com.metamx.common.StringUtils;
+
+import java.nio.ByteBuffer;
+
+/**
+ *
+ */
+public class StringFormatExtractionFn extends DimExtractionFn
+{
+  private final String format;
+
+  @JsonCreator
+  public StringFormatExtractionFn(
+      @JsonProperty("format") String format
+  )
+  {
+    Preconditions.checkArgument(!Strings.isNullOrEmpty(format), "format string should not be empty");
+    this.format = format;
+  }
+
+  @JsonProperty
+  public String getFormat()
+  {
+    return format;
+  }
+
+  @Override
+  public byte[] getCacheKey()
+  {
+    byte[] bytes = StringUtils.toUtf8(format);
+    return ByteBuffer.allocate(1 + bytes.length)
+                     .put(ExtractionCacheHelper.CACHE_TYPE_ID_STRING_FORMAT)
+                     .put(bytes)
+                     .array();
+  }
+
+  @Override
+  public String apply(String value)
+  {
+    return String.format(format, value);
+  }
+
+  @Override
+  public boolean preservesOrdering()
+  {
+    return false;
+  }
+
+  @Override
+  public ExtractionType getExtractionType()
+  {
+    return ExtractionType.MANY_TO_ONE;
+  }
+
+  @Override
+  public boolean equals(Object o)
+  {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+
+    StringFormatExtractionFn that = (StringFormatExtractionFn) o;
+
+    return format.equals(that.format);
+
+  }
+
+  @Override
+  public int hashCode()
+  {
+    return format.hashCode();
+  }
+}
diff --git a/processing/src/main/java/io/druid/query/extraction/TimeDimExtractionFn.java b/processing/src/main/java/io/druid/query/extraction/TimeDimExtractionFn.java
index ccb757b5d6f..acf14517781 100644
--- a/processing/src/main/java/io/druid/query/extraction/TimeDimExtractionFn.java
+++ b/processing/src/main/java/io/druid/query/extraction/TimeDimExtractionFn.java
@@ -33,8 +33,6 @@ import java.util.Date;
  */
 public class TimeDimExtractionFn extends DimExtractionFn
 {
-  private static final byte CACHE_TYPE_ID = 0x0;
-
   private final String timeFormat;
   private final SimpleDateFormat timeFormatter;
   private final String resultFormat;
@@ -62,7 +60,7 @@ public class TimeDimExtractionFn extends DimExtractionFn
   {
     byte[] timeFormatBytes = StringUtils.toUtf8(timeFormat);
     return ByteBuffer.allocate(1 + timeFormatBytes.length)
-                     .put(CACHE_TYPE_ID)
+                     .put(ExtractionCacheHelper.CACHE_TYPE_ID_TIME_DIM)
                      .put(timeFormatBytes)
                      .array();
   }
diff --git a/processing/src/main/java/io/druid/query/extraction/TimeFormatExtractionFn.java b/processing/src/main/java/io/druid/query/extraction/TimeFormatExtractionFn.java
index f86331f321e..2ee2011e701 100644
--- a/processing/src/main/java/io/druid/query/extraction/TimeFormatExtractionFn.java
+++ b/processing/src/main/java/io/druid/query/extraction/TimeFormatExtractionFn.java
@@ -32,8 +32,6 @@ import java.util.Locale;
 
 public class TimeFormatExtractionFn implements ExtractionFn
 {
-  private static final byte CACHE_TYPE_ID = 0x5;
-
   private final DateTimeZone tz;
   private final String pattern;
   private final Locale locale;
@@ -82,7 +80,7 @@ public class TimeFormatExtractionFn implements ExtractionFn
   {
     byte[] exprBytes = StringUtils.toUtf8(pattern + "\u0001" + tz.getID() + "\u0001" + locale.toLanguageTag());
     return ByteBuffer.allocate(1 + exprBytes.length)
-                     .put(CACHE_TYPE_ID)
+                     .put(ExtractionCacheHelper.CACHE_TYPE_ID_TIME_FORMAT)
                      .put(exprBytes)
                      .array();
   }
@@ -102,7 +100,7 @@ public class TimeFormatExtractionFn implements ExtractionFn
   @Override
   public String apply(String value)
   {
-    return apply((Object)value);
+    return apply((Object) value);
   }
 
   @Override
diff --git a/processing/src/test/java/io/druid/query/extraction/StringFormatExtractionFnTest.java b/processing/src/test/java/io/druid/query/extraction/StringFormatExtractionFnTest.java
new file mode 100644
index 00000000000..866e8449d43
--- /dev/null
+++ b/processing/src/test/java/io/druid/query/extraction/StringFormatExtractionFnTest.java
@@ -0,0 +1,67 @@
+/*
+* Licensed to Metamarkets Group Inc. (Metamarkets) under one
+* or more contributor license agreements. See the NOTICE file
+* distributed with this work for additional information
+* regarding copyright ownership. Metamarkets 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.
+*/
+
+package io.druid.query.extraction;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import io.druid.jackson.DefaultObjectMapper;
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ *
+ */
+public class StringFormatExtractionFnTest
+{
+
+  @Test
+  public void testApply() throws Exception
+  {
+    StringFormatExtractionFn fn = new StringFormatExtractionFn("[%s]");
+    long test = 1000L;
+    Assert.assertEquals("[1000]", fn.apply(test));
+  }
+
+  @Test
+  public void testApplyNull() throws Exception
+  {
+    StringFormatExtractionFn fn = new StringFormatExtractionFn("[%s]");
+    String test = null;
+    Assert.assertEquals("[null]", fn.apply(test));
+  }
+
+  @Test
+  public void testSerde() throws Exception
+  {
+    final ObjectMapper objectMapper = new DefaultObjectMapper();
+    final String json = "{ \"type\" : \"stringFormat\", \"format\" : \"[%s]\" }";
+    StringFormatExtractionFn extractionFn = (StringFormatExtractionFn) objectMapper.readValue(json, ExtractionFn.class);
+
+    Assert.assertEquals("[%s]", extractionFn.getFormat());
+
+    // round trip
+    Assert.assertEquals(
+        extractionFn,
+        objectMapper.readValue(
+            objectMapper.writeValueAsBytes(extractionFn),
+            ExtractionFn.class
+        )
+    );
+  }
+}