feat(query): support mode function

source/libs/function/inc/builtinsimpl.h

@@ -191,6 +191,11 @@ bool getUniqueFuncEnv(struct SFunctionNode* pFunc, SFuncExecEnv* pEnv);
 bool uniqueFunctionSetup(SqlFunctionCtx *pCtx, SResultRowEntryInfo* pResultInfo);
 int32_t uniqueFunction(SqlFunctionCtx *pCtx);
 
+bool getModeFuncEnv(struct SFunctionNode* pFunc, SFuncExecEnv* pEnv);
+bool modeFunctionSetup(SqlFunctionCtx *pCtx, SResultRowEntryInfo* pResultInfo);
+int32_t modeFunction(SqlFunctionCtx *pCtx);
+int32_t modeFinalize(SqlFunctionCtx* pCtx, SSDataBlock* pBlock);
+
 bool getTwaFuncEnv(struct SFunctionNode* pFunc, SFuncExecEnv* pEnv);
 bool twaFunctionSetup(SqlFunctionCtx *pCtx, SResultRowEntryInfo* pResultInfo);
 int32_t twaFunction(SqlFunctionCtx *pCtx);

source/libs/function/src/builtins.c

@@ -1045,20 +1045,28 @@ static int32_t translateFirstLastMerge(SFunctionNode* pFunc, char* pErrBuf, int3
   return translateFirstLastImpl(pFunc, pErrBuf, len, false);
 }
 
-static int32_t translateUnique(SFunctionNode* pFunc, char* pErrBuf, int32_t len) {
+static int32_t translateUniqueMode(SFunctionNode* pFunc, char* pErrBuf, int32_t len, bool isUnique) {
   if (1 != LIST_LENGTH(pFunc->pParameterList)) {
     return invaildFuncParaNumErrMsg(pErrBuf, len, pFunc->functionName);
   }
 
   SNode* pPara = nodesListGetNode(pFunc->pParameterList, 0);
   if (!nodesExprHasColumn(pPara)) {
-    return buildFuncErrMsg(pErrBuf, len, TSDB_CODE_FUNC_FUNTION_ERROR, "The parameters of UNIQUE must contain columns");
+    return buildFuncErrMsg(pErrBuf, len, TSDB_CODE_FUNC_FUNTION_ERROR, "The parameters of %s must contain columns", isUnique ? "UNIQUE" : "MODE");
   }
 
   pFunc->node.resType = ((SExprNode*)pPara)->resType;
   return TSDB_CODE_SUCCESS;
 }
 
+static int32_t translateUnique(SFunctionNode* pFunc, char* pErrBuf, int32_t len) {
+  return translateUniqueMode(pFunc, pErrBuf, len, true);
+}
+
+static int32_t translateMode(SFunctionNode* pFunc, char* pErrBuf, int32_t len) {
+  return translateUniqueMode(pFunc, pErrBuf, len, false);
+}
+
 static int32_t translateDiff(SFunctionNode* pFunc, char* pErrBuf, int32_t len) {
   int32_t numOfParams = LIST_LENGTH(pFunc->pParameterList);
   if (numOfParams == 0 || numOfParams > 2) {
@@ -2109,7 +2117,7 @@ const SBuiltinFuncDefinition funcMgtBuiltins[] = {
   {
     .name = "unique",
     .type = FUNCTION_TYPE_UNIQUE,
-    .classification = FUNC_MGT_AGG_FUNC | FUNC_MGT_SELECT_FUNC | FUNC_MGT_INDEFINITE_ROWS_FUNC | FUNC_MGT_TIMELINE_FUNC | 
+    .classification = FUNC_MGT_AGG_FUNC | FUNC_MGT_SELECT_FUNC | FUNC_MGT_INDEFINITE_ROWS_FUNC | FUNC_MGT_TIMELINE_FUNC |
                       FUNC_MGT_FORBID_STREAM_FUNC | FUNC_MGT_FORBID_WINDOW_FUNC | FUNC_MGT_FORBID_GROUP_BY_FUNC,
     .translateFunc = translateUnique,
     .getEnvFunc   = getUniqueFuncEnv,
@@ -2117,6 +2125,16 @@ const SBuiltinFuncDefinition funcMgtBuiltins[] = {
     .processFunc  = uniqueFunction,
     .finalizeFunc = NULL
   },
+  {
+    .name = "mode",
+    .type = FUNCTION_TYPE_MODE,
+    .classification = FUNC_MGT_AGG_FUNC,
+    .translateFunc = translateMode,
+    .getEnvFunc   = getUniqueFuncEnv,
+    .initFunc     = uniqueFunctionSetup,
+    .processFunc  = uniqueFunction,
+    .finalizeFunc = functionFinalize,
+  },
   {
     .name = "abs",
     .type = FUNCTION_TYPE_ABS,