diff --git a/src/backend/executor/execHHashagg.c b/src/backend/executor/execHHashagg.c
index aa70fefbb9da9f156a0a48d0235b9513471627c5..56984e8b9b33185ac5227711fadf06e7313ff803 100644
--- a/src/backend/executor/execHHashagg.c
+++ b/src/backend/executor/execHHashagg.c
@@ -340,7 +340,10 @@ makeHashAggEntryForInput(AggState *aggstate, TupleTableSlot *inputslot, uint32 h
 
 	if (GET_TOTAL_USED_SIZE(hashtable) + MAXALIGN(MAXALIGN(tup_len) + aggs_len) >=
 		hashtable->max_mem)
+	{
+		MemoryContextSwitchTo(oldcxt);
 		return NULL;
+	}
 
 	/*
 	 * Form memtuple into group_buf.
@@ -391,7 +394,11 @@ makeHashAggEntryForGroup(AggState *aggstate, void *tuple_and_aggs,
 	copy_tuple_and_aggs = mpool_alloc(hashtable->group_buf, input_size);
 	memcpy(copy_tuple_and_aggs, tuple_and_aggs, input_size);
 
-	oldcxt = MemoryContextSwitchTo(hashtable->entry_cxt);
+	/*
+	 * The deserialized transValues are not in mpool, put them
+	 * in a separate context and reset with mpool_reset
+	 */
+	oldcxt = MemoryContextSwitchTo(hashtable->serialization_cxt);
 
 	entry = getEmptyHashAggEntry(aggstate);
 	entry->hashvalue = hashvalue;
@@ -809,6 +816,12 @@ create_agg_hash_table(AggState *aggstate)
 												 ALLOCSET_DEFAULT_INITSIZE,
 												 ALLOCSET_DEFAULT_MAXSIZE);
 
+	hashtable->serialization_cxt = AllocSetContextCreate(hashtable->entry_cxt,
+												 "HashAggTableEntrySerializationlContext",
+												 ALLOCSET_DEFAULT_MINSIZE,
+												 ALLOCSET_DEFAULT_INITSIZE,
+												 ALLOCSET_DEFAULT_MAXSIZE);
+
 	uint64 operatorMemKB = PlanStateOperatorMemKB( (PlanState *) aggstate);
 
 	keywidth = est_hash_tuple_size(aggstate->ss.ss_ScanTupleSlot, aggstate->hash_needed);
@@ -1404,6 +1417,9 @@ spill_hash_table(AggState *aggstate)
 	/* Reset the buffer */
 	mpool_reset(hashtable->group_buf);
 
+	/* Reset serialization context */
+	MemoryContextReset(hashtable->serialization_cxt);
+
 	/* Reset in-memory entries count */
 	hashtable->num_entries = 0;
 
@@ -1571,6 +1587,7 @@ writeHashEntry(AggState *aggstate, BatchFileInfo *file_info,
 		if (OidIsValid(peraggstate->serialfn_oid))
 		{
 			FunctionCallInfoData fcinfo;
+			MemoryContext old_ctx;
 
 			InitFunctionCallInfoData(fcinfo,
 									 &peraggstate->serialfn,
@@ -1581,12 +1598,17 @@ writeHashEntry(AggState *aggstate, BatchFileInfo *file_info,
 			fcinfo.arg[0] = pergroupstate->transValue;
 			fcinfo.argnull[0] = pergroupstate->transValueIsNull;
 
+			/* Not necessary to do this if the serialization func has no memory leak */
+			old_ctx = MemoryContextSwitchTo(aggstate->hhashtable->serialization_cxt);
+
 			serializedVal = FunctionCallInvoke(&fcinfo);
 
 			datum_size = datumGetSize(serializedVal, byteaTranstypeByVal, byteaTranstypeLen);
 			BufFileWriteOrError(file_info->wfile,
 								DatumGetPointer(serializedVal), datum_size);
 			pfree(DatumGetPointer(serializedVal));
+
+			MemoryContextSwitchTo(old_ctx);
 		}
 		/* If it's a ByRef, write the data to the file */
 		else if (!peraggstate->transtypeByVal)
@@ -2316,6 +2338,8 @@ void reset_agg_hash_table(AggState *aggstate, int64 nentries)
 
 	mpool_reset(hashtable->group_buf);
 
+	MemoryContextReset(hashtable->serialization_cxt);
+
 	init_agg_hash_iter(hashtable);
 
 	Gpmon_ResetAggHashTable(aggstate);
diff --git a/src/include/executor/execHHashagg.h b/src/include/executor/execHHashagg.h
index 2ce05fcd579359828bc5191c94087586b0d0d678..a9f7cb861b8d69dd07dd9eb2b53d3e199abae7b2 100644
--- a/src/include/executor/execHHashagg.h
+++ b/src/include/executor/execHHashagg.h
@@ -168,6 +168,9 @@ typedef struct HashAggTable
 	SpillFile *curr_spill_file;
 	int curr_spill_level;
 
+	/* The memory context for (de)serialization */
+	MemoryContext serialization_cxt;
+
 	/*
 	 * The space to buffer the free hash entries and AggStatePerGroups. Using this,
 	 * we can reduce palloc/pfree calls.