diff --git a/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/BoundedColumnValuePartitionFunction.java b/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/BoundedColumnValuePartitionFunction.java
index ce52909fe3..ed550974d4 100644
--- a/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/BoundedColumnValuePartitionFunction.java
+++ b/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/BoundedColumnValuePartitionFunction.java
@@ -47,6 +47,7 @@ public class BoundedColumnValuePartitionFunction implements PartitionFunction {
   private final int _numPartitions;
   private final Map<String, String> _functionConfig;
   private final String[] _values;
+  private final String _partitionFunctionKey;
 
   public BoundedColumnValuePartitionFunction(int numPartitions, Map<String, String> functionConfig) {
     Preconditions.checkArgument(functionConfig != null && functionConfig.size() > 0,
@@ -59,6 +60,8 @@ public BoundedColumnValuePartitionFunction(int numPartitions, Map<String, String
     Preconditions.checkState(numPartitions == _values.length + 1,
         "'numPartitions' must just be one greater than number of column values configured");
     _numPartitions = numPartitions;
+    _partitionFunctionKey = NAME + "_" + _numPartitions + "_" + _functionConfig.get(COLUMN_VALUES)
+        + "_" + _functionConfig.get(COLUMN_VALUES_DELIMITER);
   }
 
   @Override
@@ -98,7 +101,6 @@ public String toString() {
 
   @Override
   public String getPartitionFunctionKey() {
-    return NAME + "_" + _numPartitions + "_" + _functionConfig.get(COLUMN_VALUES)
-        + "_" + _functionConfig.get(COLUMN_VALUES_DELIMITER);
+    return _partitionFunctionKey;
   }
 }
diff --git a/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/ByteArrayPartitionFunction.java b/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/ByteArrayPartitionFunction.java
index e8ff8edc24..fc3ff5b505 100644
--- a/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/ByteArrayPartitionFunction.java
+++ b/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/ByteArrayPartitionFunction.java
@@ -31,6 +31,7 @@
 public class ByteArrayPartitionFunction implements PartitionFunction {
   private static final String NAME = "ByteArray";
   private final int _numPartitions;
+  private final String _partitionFunctionKey;
 
   /**
    * Constructor for the class.
@@ -39,6 +40,7 @@ public class ByteArrayPartitionFunction implements PartitionFunction {
   public ByteArrayPartitionFunction(int numPartitions) {
     Preconditions.checkArgument(numPartitions > 0, "Number of partitions must be > 0, specified", numPartitions);
     _numPartitions = numPartitions;
+    _partitionFunctionKey = NAME + "_" + _numPartitions;
   }
 
   @Override
@@ -56,6 +58,11 @@ public int getNumPartitions() {
     return _numPartitions;
   }
 
+  @Override
+  public String getPartitionFunctionKey() {
+    return _partitionFunctionKey;
+  }
+
   // Keep it for backward-compatibility, use getName() instead
   @Override
   public String toString() {
diff --git a/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/HashCodePartitionFunction.java b/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/HashCodePartitionFunction.java
index 182760cf44..528fb7fa1f 100644
--- a/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/HashCodePartitionFunction.java
+++ b/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/HashCodePartitionFunction.java
@@ -30,10 +30,12 @@
 public class HashCodePartitionFunction implements PartitionFunction {
   private static final String NAME = "HashCode";
   private final int _numPartitions;
+  private final String _partitionFunctionKey;
 
   public HashCodePartitionFunction(int numPartitions) {
     Preconditions.checkArgument(numPartitions > 0, "Number of partitions must be > 0, specified", numPartitions);
     _numPartitions = numPartitions;
+    _partitionFunctionKey = NAME + "_" + _numPartitions;
   }
 
   @Override
@@ -51,6 +53,11 @@ public int getNumPartitions() {
     return _numPartitions;
   }
 
+  @Override
+  public String getPartitionFunctionKey() {
+    return _partitionFunctionKey;
+  }
+
   // Keep it for backward-compatibility, use getName() instead
   @Override
   public String toString() {
diff --git a/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/ModuloPartitionFunction.java b/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/ModuloPartitionFunction.java
index a4b8eb49ab..6afbcb7585 100644
--- a/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/ModuloPartitionFunction.java
+++ b/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/ModuloPartitionFunction.java
@@ -31,6 +31,7 @@
 public class ModuloPartitionFunction implements PartitionFunction {
   private static final String NAME = "Modulo";
   private final int _numPartitions;
+  private final String _partitionFunctionKey;
 
   /**
    * Constructor for the class.
@@ -39,6 +40,7 @@ public class ModuloPartitionFunction implements PartitionFunction {
   public ModuloPartitionFunction(int numPartitions) {
     Preconditions.checkArgument(numPartitions > 0, "Number of partitions must be > 0, specified", numPartitions);
     _numPartitions = numPartitions;
+    _partitionFunctionKey = NAME + "_" + _numPartitions;
   }
 
   /**
@@ -63,6 +65,11 @@ public int getNumPartitions() {
     return _numPartitions;
   }
 
+  @Override
+  public String getPartitionFunctionKey() {
+    return _partitionFunctionKey;
+  }
+
   // Keep it for backward-compatibility, use getName() instead
   @Override
   public String toString() {
diff --git a/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/Murmur3PartitionFunction.java b/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/Murmur3PartitionFunction.java
index 18b03b5de4..8a82373e7d 100644
--- a/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/Murmur3PartitionFunction.java
+++ b/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/Murmur3PartitionFunction.java
@@ -36,6 +36,7 @@ public class Murmur3PartitionFunction implements PartitionFunction {
   private final int _numPartitions;
   private final int _seed;
   private final boolean _useX64;
+  private final String _partitionFunctionKey;
 
   /**
    * Constructor for the class.
@@ -65,6 +66,7 @@ public Murmur3PartitionFunction(int numPartitions, Map<String, String> functionC
     }
     _seed = seed;
     _useX64 = useX64;
+    _partitionFunctionKey = NAME + "_" + _numPartitions + "_" + _seed + "_" + (_useX64 ? "x64" : "x86");
   }
 
   @Override
@@ -92,6 +94,6 @@ public String toString() {
 
   @Override
   public String getPartitionFunctionKey() {
-    return NAME + "_" + _numPartitions + "_" + _seed + "_" + (_useX64 ? "x64" : "x86");
+    return _partitionFunctionKey;
   }
 }
diff --git a/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/MurmurPartitionFunction.java b/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/MurmurPartitionFunction.java
index 8251450c44..3970db9b9c 100644
--- a/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/MurmurPartitionFunction.java
+++ b/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/partition/MurmurPartitionFunction.java
@@ -30,6 +30,7 @@
 public class MurmurPartitionFunction implements PartitionFunction {
   private static final String NAME = "Murmur";
   private final int _numPartitions;
+  private final String _partitionFunctionKey;
 
   /**
    * Constructor for the class.
@@ -38,6 +39,7 @@ public class MurmurPartitionFunction implements PartitionFunction {
   public MurmurPartitionFunction(int numPartitions) {
     Preconditions.checkArgument(numPartitions > 0, "Number of partitions must be > 0");
     _numPartitions = numPartitions;
+    _partitionFunctionKey = NAME + "_" + _numPartitions;
   }
 
   @Override
@@ -55,6 +57,11 @@ public int getNumPartitions() {
     return _numPartitions;
   }
 
+  @Override
+  public String getPartitionFunctionKey() {
+    return _partitionFunctionKey;
+  }
+
   // Keep it for backward-compatibility, use getName() instead
   @Override
   public String toString() {
diff --git a/pinot-segment-spi/src/test/java/org/apache/pinot/segment/spi/partition/PartitionFunctionTest.java b/pinot-segment-spi/src/test/java/org/apache/pinot/segment/spi/partition/PartitionFunctionTest.java
index c2f5b7d75d..69bb422856 100644
--- a/pinot-segment-spi/src/test/java/org/apache/pinot/segment/spi/partition/PartitionFunctionTest.java
+++ b/pinot-segment-spi/src/test/java/org/apache/pinot/segment/spi/partition/PartitionFunctionTest.java
@@ -28,6 +28,7 @@
 
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.testng.Assert.assertEquals;
+import static org.testng.Assert.assertSame;
 import static org.testng.Assert.assertTrue;
 
 
@@ -417,6 +418,31 @@ public void testPartitionFunctionKey() {
     assertTrue(!murmur3Function.getPartitionFunctionKey().equals(murmur3DifferentSeed.getPartitionFunctionKey()));
   }
 
+  @Test
+  public void testPartitionFunctionKeyIsPrecomputed() {
+    // The key is computed once and called per-segment on the broker's hot pruning path. Verify each implementation
+    // returns the same cached instance on repeated calls rather than rebuilding the string every time.
+    Map<String, String> murmur3Config = new HashMap<>();
+    murmur3Config.put("seed", "42");
+    murmur3Config.put("variant", "x64_32");
+    Map<String, String> boundedConfig = new HashMap<>();
+    boundedConfig.put("columnValues", "a|b|c");
+    boundedConfig.put("columnValuesDelimiter", "|");
+
+    PartitionFunction[] functions = {
+        PartitionFunctionFactory.getPartitionFunction("Modulo", 10, null),
+        PartitionFunctionFactory.getPartitionFunction("HashCode", 20, null),
+        PartitionFunctionFactory.getPartitionFunction("Murmur", 15, null),
+        PartitionFunctionFactory.getPartitionFunction("Murmur3", 25, murmur3Config),
+        PartitionFunctionFactory.getPartitionFunction("ByteArray", 12, null),
+        PartitionFunctionFactory.getPartitionFunction("BoundedColumnValue", 4, boundedConfig)
+    };
+    for (PartitionFunction function : functions) {
+      assertSame(function.getPartitionFunctionKey(), function.getPartitionFunctionKey(),
+          function.getName() + " should return the same precomputed key instance on every call");
+    }
+  }
+
   private void testBasicProperties(PartitionFunction partitionFunction, String functionName, int numPartitions) {
     testBasicProperties(partitionFunction, functionName, numPartitions, null);
   }