refactor: do some internal refactor of sample function.

source/libs/function/inc/builtinsimpl.h

@@ -155,6 +155,7 @@ int32_t mavgFunction(SqlFunctionCtx* pCtx);
 bool getSampleFuncEnv(struct SFunctionNode* pFunc, SFuncExecEnv* pEnv);
 bool sampleFunctionSetup(SqlFunctionCtx *pCtx, SResultRowEntryInfo* pResultInfo);
 int32_t sampleFunction(SqlFunctionCtx* pCtx);
+int32_t sampleFinalize(SqlFunctionCtx* pCtx, SSDataBlock* pBlock);
 
 bool getTailFuncEnv(struct SFunctionNode* pFunc, SFuncExecEnv* pEnv);
 bool tailFunctionSetup(SqlFunctionCtx *pCtx, SResultRowEntryInfo* pResultInfo);

source/libs/function/src/builtins.c

@@ -1751,12 +1751,12 @@ const SBuiltinFuncDefinition funcMgtBuiltins[] = {
   {
     .name = "sample",
     .type = FUNCTION_TYPE_SAMPLE,
-    .classification = FUNC_MGT_INDEFINITE_ROWS_FUNC | FUNC_MGT_TIMELINE_FUNC,
+    .classification = FUNC_MGT_AGG_FUNC | FUNC_MGT_SELECT_FUNC | FUNC_MGT_INDEFINITE_ROWS_FUNC,
     .translateFunc = translateSample,
     .getEnvFunc   = getSampleFuncEnv,
     .initFunc     = sampleFunctionSetup,
     .processFunc  = sampleFunction,
-    .finalizeFunc = NULL
+    .finalizeFunc = sampleFinalize
   },
   {
     .name = "tail",

source/libs/function/src/builtinsimpl.c

@@ -198,7 +198,7 @@ typedef struct SSampleInfo {
   int32_t numSampled;
   uint8_t colType;
   int16_t colBytes;
-  char *data;
+  char    *data;
   int64_t *timestamp;
 } SSampleInfo;
 
@@ -4183,28 +4183,38 @@ int32_t sampleFunction(SqlFunctionCtx* pCtx) {
   SSampleInfo*         pInfo = GET_ROWCELL_INTERBUF(pResInfo);
 
   SInputColumnInfoData* pInput = &pCtx->input;
-  TSKEY* tsList = (int64_t*)pInput->pPTS->pData;
-
-  SColumnInfoData* pInputCol = pInput->pData[0];
-  SColumnInfoData* pOutput = (SColumnInfoData*)pCtx->pOutput;
 
-  int32_t alreadySampled = pInfo->numSampled;
+  TSKEY* tsList = NULL;
+  if (pInput->pPTS != NULL) {
+    tsList = (int64_t*)pInput->pPTS->pData;
+  }
 
-  int32_t startOffset = pCtx->offset;
+  SColumnInfoData* pInputCol = pInput->pData[0];
   for (int32_t i = pInput->startRowIndex; i < pInput->numOfRows + pInput->startRowIndex; i += 1) {
     if (colDataIsNull_s(pInputCol, i)) {
-      //colDataAppendNULL(pOutput, i);
       continue;
     }
 
     char* data = colDataGetData(pInputCol, i);
-    doReservoirSample(pInfo, data, tsList[i], i);
+    doReservoirSample(pInfo, data, /*tsList[i]*/0, i);
   }
 
+  SET_VAL(pResInfo, pInfo->numSampled, pInfo->numSampled);
+  return TSDB_CODE_SUCCESS;
+}
+
+int32_t sampleFinalize(SqlFunctionCtx* pCtx, SSDataBlock* pBlock) {
+  SResultRowEntryInfo* pEntryInfo = GET_RES_INFO(pCtx);
+
+  SSampleInfo* pInfo = GET_ROWCELL_INTERBUF(pEntryInfo);
+  pEntryInfo->complete = true;
+
+  int32_t slotId = pCtx->pExpr->base.resSchema.slotId;
+  SColumnInfoData* pCol = taosArrayGet(pBlock->pDataBlock, slotId);
+
+  int32_t currentRow = pBlock->info.rows;
   for (int32_t i = 0; i < pInfo->numSampled; ++i) {
-    int32_t pos = startOffset + i;
-    colDataAppend(pOutput, pos, pInfo->data + i * pInfo->colBytes, false);
-    //TODO: handle ts output
+    colDataAppend(pCol, currentRow + i, pInfo->data + i * pInfo->colBytes, false);
   }
 
   return pInfo->numSampled;