diff --git a/include/libs/function/taosudf.h b/include/libs/function/taosudf.h
index 5e84b87a81..2b2063e3f6 100644
--- a/include/libs/function/taosudf.h
+++ b/include/libs/function/taosudf.h
@@ -256,8 +256,9 @@ static FORCE_INLINE int32_t udfColDataSet(SUdfColumn* pColumn, uint32_t currentR
 typedef int32_t (*TUdfScalarProcFunc)(SUdfDataBlock* block, SUdfColumn *resultCol);
 
 typedef int32_t (*TUdfAggStartFunc)(SUdfInterBuf *buf);
-typedef int32_t (*TUdfAggProcessFunc)(SUdfDataBlock* block, SUdfInterBuf *interBuf, SUdfInterBuf *newInterBuf);
-typedef int32_t (*TUdfAggFinishFunc)(SUdfInterBuf* buf, SUdfInterBuf *resultData);
+typedef int32_t (*TUdfAggProcessFunc)(SUdfDataBlock *block, SUdfInterBuf *interBuf, SUdfInterBuf *newInterBuf);
+typedef int32_t (*TUdfAggMergeFunc)(SUdfInterBuf *inputBuf1, SUdfInterBuf *inputBuf2, SUdfInterBuf *outputBuf);
+typedef int32_t (*TUdfAggFinishFunc)(SUdfInterBuf *buf, SUdfInterBuf *resultData);
 
 #ifdef __cplusplus
 }
diff --git a/source/common/src/tdatablock.c b/source/common/src/tdatablock.c
index c65e966046..c748260918 100644
--- a/source/common/src/tdatablock.c
+++ b/source/common/src/tdatablock.c
@@ -1706,8 +1706,8 @@ static char* formatTimestamp(char* buf, int64_t val, int precision) {
 }
 
 void blockDebugShowDataBlock(SSDataBlock* pBlock, const char* flag) {
-  SArray* dataBlocks = taosArrayInit(1, sizeof(SSDataBlock));
-  taosArrayPush(dataBlocks, pBlock);
+  SArray* dataBlocks = taosArrayInit(1, sizeof(SSDataBlock*));
+  taosArrayPush(dataBlocks, &pBlock);
   blockDebugShowDataBlocks(dataBlocks, flag);
   taosArrayDestroy(dataBlocks);
 }
diff --git a/source/libs/function/src/udfd.c b/source/libs/function/src/udfd.c
index 1cbc78df48..5b27e030b9 100644
--- a/source/libs/function/src/udfd.c
+++ b/source/libs/function/src/udfd.c
@@ -84,6 +84,7 @@ typedef struct SUdf {
   TUdfAggStartFunc   aggStartFunc;
   TUdfAggProcessFunc aggProcFunc;
   TUdfAggFinishFunc  aggFinishFunc;
+  TUdfAggMergeFunc   aggMergeFunc;
 
   TUdfInitFunc    initFunc;
   TUdfDestroyFunc destroyFunc;
@@ -271,6 +272,15 @@ void udfdProcessCallRequest(SUvUdfWork *uvUdf, SUdfRequest *request) {
 
       break;
     }
+    case TSDB_UDF_CALL_AGG_MERGE: {
+      SUdfInterBuf outBuf = {.buf = taosMemoryMalloc(udf->bufSize), .bufLen = udf->bufSize, .numOfResult = 0};
+      code = udf->aggMergeFunc(&call->interBuf, &call->interBuf2, &outBuf);
+      freeUdfInterBuf(&call->interBuf);
+      freeUdfInterBuf(&call->interBuf2);
+      subRsp->resultBuf = outBuf;
+
+      break;
+    }
     case TSDB_UDF_CALL_AGG_FIN: {
       SUdfInterBuf outBuf = {.buf = taosMemoryMalloc(udf->bufSize), .bufLen = udf->bufSize, .numOfResult = 0};
       code = udf->aggFinishFunc(&call->interBuf, &outBuf);
@@ -309,6 +319,10 @@ void udfdProcessCallRequest(SUvUdfWork *uvUdf, SUdfRequest *request) {
       freeUdfInterBuf(&subRsp->resultBuf);
       break;
     }
+    case TSDB_UDF_CALL_AGG_MERGE: {
+      freeUdfInterBuf(&subRsp->resultBuf);
+      break;
+    }
     case TSDB_UDF_CALL_AGG_FIN: {
       freeUdfInterBuf(&subRsp->resultBuf);
       break;
@@ -560,7 +574,11 @@ int32_t udfdLoadUdf(char *udfName, SUdf *udf) {
     strncpy(finishFuncName, processFuncName, strlen(processFuncName));
     strncat(finishFuncName, finishSuffix, strlen(finishSuffix));
     uv_dlsym(&udf->lib, finishFuncName, (void **)(&udf->aggFinishFunc));
-    // TODO: merge
+    char mergeFuncName[TSDB_FUNC_NAME_LEN + 6] = {0};
+    char *mergeSuffix = "_merge";
+    strncpy(finishFuncName, processFuncName, strlen(processFuncName));
+    strncat(finishFuncName, mergeSuffix, strlen(mergeSuffix));
+    uv_dlsym(&udf->lib, finishFuncName, (void **)(&udf->aggMergeFunc));
   }
   return 0;
 }