From c07bea7ff5ab4083c78c8359b20b2eb4a33ea7bb Mon Sep 17 00:00:00 2001
From: Ganlin Zhao <ganlinzhao@hotmail.com>
Date: Wed, 8 Jun 2022 18:40:16 +0800
Subject: [PATCH] add histogram partial/merge function

---
 source/libs/function/src/builtinsimpl.c | 45 +++++++++++++++++++++++--
 1 file changed, 42 insertions(+), 3 deletions(-)

diff --git a/source/libs/function/src/builtinsimpl.c b/source/libs/function/src/builtinsimpl.c
index fc72a05edb..41414efba5 100644
--- a/source/libs/function/src/builtinsimpl.c
+++ b/source/libs/function/src/builtinsimpl.c
@@ -2187,9 +2187,7 @@ int32_t apercentilePartialFinalize(SqlFunctionCtx* pCtx, SSDataBlock* pBlock) {
   SResultRowEntryInfo* pResInfo = GET_RES_INFO(pCtx);
   SAPercentileInfo*       pInfo = (SAPercentileInfo*)GET_ROWCELL_INTERBUF(pResInfo);
 
-  int32_t bytesHist   = (int32_t)(sizeof(SAPercentileInfo) + sizeof(SHistogramInfo) + sizeof(SHistBin) * (MAX_HISTOGRAM_BIN + 1));
-  int32_t bytesDigest = (int32_t)(sizeof(SAPercentileInfo) + TDIGEST_SIZE(COMPRESSION));
-  int32_t resultBytes = TMAX(bytesHist, bytesDigest);
+  int32_t resultBytes = getApercentileMaxSize();
   char *res = taosMemoryCalloc(resultBytes + VARSTR_HEADER_SIZE, sizeof(char));
 
   if (pInfo->algo == APERCT_ALGO_TDIGEST) {
@@ -3332,6 +3330,29 @@ int32_t histogramFunction(SqlFunctionCtx *pCtx) {
   return TSDB_CODE_SUCCESS;
 }
 
+int32_t histogramFunctionMerge(SqlFunctionCtx *pCtx) {
+  SInputColumnInfoData* pInput = &pCtx->input;
+  SColumnInfoData* pCol = pInput->pData[0];
+  ASSERT(pCol->info.type == TSDB_DATA_TYPE_BINARY);
+
+  SHistoFuncInfo* pInfo = GET_ROWCELL_INTERBUF(GET_RES_INFO(pCtx));
+
+  int32_t start = pInput->startRowIndex;
+  char* data = colDataGetData(pCol, start);
+  SHistoFuncInfo* pInputInfo = (SHistoFuncInfo *)varDataVal(data);
+
+  pInfo->normalized = pInputInfo->normalized;
+  pInfo->numOfBins  = pInputInfo->numOfBins;
+  pInfo->totalCount += pInputInfo->totalCount;
+  for (int32_t k = 0; k < pInfo->numOfBins; ++k) {
+    pInfo->bins[k].count += pInputInfo->bins[k].count;
+  }
+
+  SET_VAL(GET_RES_INFO(pCtx), 1, 1);
+
+  return TSDB_CODE_SUCCESS;
+}
+
 int32_t histogramFinalize(SqlFunctionCtx* pCtx, SSDataBlock* pBlock) {
   SResultRowEntryInfo* pResInfo = GET_RES_INFO(pCtx);
   SHistoFuncInfo* pInfo = GET_ROWCELL_INTERBUF(GET_RES_INFO(pCtx));
@@ -3368,6 +3389,24 @@ int32_t histogramFinalize(SqlFunctionCtx* pCtx, SSDataBlock* pBlock) {
   return pResInfo->numOfRes;
 }
 
+int32_t histogramPartialFinalize(SqlFunctionCtx* pCtx, SSDataBlock* pBlock) {
+  SResultRowEntryInfo* pResInfo = GET_RES_INFO(pCtx);
+  SHistoFuncInfo* pInfo = GET_ROWCELL_INTERBUF(GET_RES_INFO(pCtx));
+  int32_t resultBytes = getHistogramInfoSize();
+  char *res = taosMemoryCalloc(resultBytes + VARSTR_HEADER_SIZE, sizeof(char));
+
+  memcpy(varDataVal(res), pInfo, resultBytes);
+  varDataSetLen(res, resultBytes);
+
+  int32_t          slotId = pCtx->pExpr->base.resSchema.slotId;
+  SColumnInfoData* pCol = taosArrayGet(pBlock->pDataBlock, slotId);
+
+  colDataAppend(pCol, pBlock->info.rows, res, false);
+
+  taosMemoryFree(res);
+  return pResInfo->numOfRes;
+}
+
 bool getHLLFuncEnv(SFunctionNode* UNUSED_PARAM(pFunc), SFuncExecEnv* pEnv) {
   pEnv->calcMemSize = sizeof(SHLLInfo);
   return true;
-- 
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