fix(query): add mode function

include/util/taoserror.h

@@ -25,7 +25,7 @@ extern "C" {
 // clang-format off
 
 #define TAOS_DEF_ERROR_CODE(mod, code) ((int32_t)((0x80000000 | ((mod)<<16) | (code))))
- 
+
 #define TAOS_SYSTEM_ERROR(code)             (0x80ff0000 | (code))
 #define TAOS_SUCCEEDED(err)                 ((err) >= 0)
 #define TAOS_FAILED(err)                    ((err) < 0)
@@ -35,7 +35,7 @@ const char* terrstr();
 
 int32_t* taosGetErrno();
 #define terrno                              (*taosGetErrno())
- 
+
 #define TSDB_CODE_SUCCESS                   0
 #define TSDB_CODE_FAILED                    -1   // unknown or needn't tell detail error
 

source/libs/function/src/builtins.c

@@ -2130,10 +2130,10 @@ const SBuiltinFuncDefinition funcMgtBuiltins[] = {
     .type = FUNCTION_TYPE_MODE,
     .classification = FUNC_MGT_AGG_FUNC,
     .translateFunc = translateMode,
-    .getEnvFunc   = getUniqueFuncEnv,
+    .getEnvFunc   = getModeFuncEnv,
-    .initFunc     = uniqueFunctionSetup,
+    .initFunc     = modeFunctionSetup,
-    .processFunc  = uniqueFunction,
+    .processFunc  = modeFunction,
-    .finalizeFunc = functionFinalize,
+    .finalizeFunc = modeFinalize,
   },
   {
     .name = "abs",

source/libs/function/src/builtinsimpl.c

@@ -32,6 +32,7 @@
 #define TAIL_MAX_OFFSET        100
 
 #define UNIQUE_MAX_RESULT_SIZE (1024 * 1024 * 10)
+#define MODE_MAX_RESULT_SIZE   UNIQUE_MAX_RESULT_SIZE
 
 #define HLL_BUCKET_BITS 14  // The bits of the bucket
 #define HLL_DATA_BITS   (64 - HLL_BUCKET_BITS)
@@ -246,6 +247,19 @@ typedef struct SUniqueInfo {
   char      pItems[];
 } SUniqueInfo;
 
+typedef struct SModeItem {
+  int64_t count;
+  char    data[];
+} SModeItem;
+
+typedef struct SModeInfo {
+  int32_t   numOfPoints;
+  uint8_t   colType;
+  int16_t   colBytes;
+  SHashObj* pHash;
+  char      pItems[];
+} SModeInfo;
+
 typedef struct SDerivInfo {
   double  prevValue;       // previous value
   TSKEY   prevTs;          // previous timestamp
@@ -4694,21 +4708,99 @@ int32_t uniqueFunction(SqlFunctionCtx* pCtx) {
   return pInfo->numOfPoints;
 }
 
-int32_t uniqueFinalize(SqlFunctionCtx* pCtx, SSDataBlock* pBlock) {
+bool getModeFuncEnv(SFunctionNode* pFunc, SFuncExecEnv* pEnv) {
+  pEnv->calcMemSize = sizeof(SModeInfo) + MODE_MAX_RESULT_SIZE;
+  return true;
+}
+
+bool modeFunctionSetup(SqlFunctionCtx* pCtx, SResultRowEntryInfo* pResInfo) {
+  if (!functionSetup(pCtx, pResInfo)) {
+    return false;
+  }
+
+  SModeInfo* pInfo = GET_ROWCELL_INTERBUF(pResInfo);
+  pInfo->numOfPoints = 0;
+  pInfo->colType = pCtx->resDataInfo.type;
+  pInfo->colBytes = pCtx->resDataInfo.bytes;
+  if (pInfo->pHash != NULL) {
+    taosHashClear(pInfo->pHash);
+  } else {
+    pInfo->pHash = taosHashInit(64, taosGetDefaultHashFunction(TSDB_DATA_TYPE_BINARY), true, HASH_NO_LOCK);
+  }
+  return true;
+}
+
+static void doModeAdd(SModeInfo* pInfo, char* data, bool isNull) {
+  // ignore null elements
+  if (isNull) {
+    return;
+  }
+
+  int32_t      hashKeyBytes = IS_VAR_DATA_TYPE(pInfo->colType) ? varDataTLen(data) : pInfo->colBytes;
+  SModeItem*      pHashItem = taosHashGet(pInfo->pHash, data, hashKeyBytes);
+  if (pHashItem == NULL) {
+    int32_t      size = sizeof(SModeItem) + pInfo->colBytes;
+    SModeItem* pItem  = (SModeItem*)(pInfo->pItems + pInfo->numOfPoints * size);
+    memcpy(pItem->data, data, pInfo->colBytes);
+    pItem->count += 1;
+
+    taosHashPut(pInfo->pHash, data, hashKeyBytes, (char*)pItem, sizeof(SModeItem*));
+    pInfo->numOfPoints++;
+  } else {
+    pHashItem->count += 1;
+  }
+}
+
+int32_t modeFunction(SqlFunctionCtx* pCtx) {
   SResultRowEntryInfo* pResInfo = GET_RES_INFO(pCtx);
-  SUniqueInfo*         pInfo = GET_ROWCELL_INTERBUF(pResInfo);
+  SModeInfo*              pInfo = GET_ROWCELL_INTERBUF(pResInfo);
+
+  SInputColumnInfoData* pInput = &pCtx->input;
+
+  SColumnInfoData* pInputCol = pInput->pData[0];
+  SColumnInfoData* pOutput = (SColumnInfoData*)pCtx->pOutput;
+
+  int32_t startOffset = pCtx->offset;
+  for (int32_t i = pInput->startRowIndex; i < pInput->numOfRows + pInput->startRowIndex; ++i) {
+    char* data = colDataGetData(pInputCol, i);
+    doModeAdd(pInfo, data, colDataIsNull_s(pInputCol, i));
+
+    if (sizeof(SModeInfo) + pInfo->numOfPoints * (sizeof(SModeItem) + pInfo->colBytes) >= MODE_MAX_RESULT_SIZE) {
+      taosHashCleanup(pInfo->pHash);
+      return TSDB_CODE_OUT_OF_MEMORY;
+    }
+  }
+
+  return TSDB_CODE_SUCCESS;
+}
+
+int32_t modeFinalize(SqlFunctionCtx* pCtx, SSDataBlock* pBlock) {
+  SResultRowEntryInfo* pResInfo = GET_RES_INFO(pCtx);
+  SModeInfo*           pInfo = GET_ROWCELL_INTERBUF(pResInfo);
   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 < pResInfo->numOfRes; ++i) {
+  int32_t resIndex;
-    SUniqueItem* pItem = (SUniqueItem*)(pInfo->pItems + i * (sizeof(SUniqueItem) + pInfo->colBytes));
+  int32_t maxCount = 0;
-    colDataAppend(pCol, i, pItem->data, false);
+  for (int32_t i = 0; i < pInfo->numOfPoints; ++i) {
-    // TODO: handle ts output
+    SModeItem* pItem = (SModeItem*)(pInfo->pItems + i * (sizeof(SModeItem) + pInfo->colBytes));
+    if (pItem->count > maxCount) {
+      maxCount = pItem->count;
+      resIndex = i;
+    } else if (pItem->count == maxCount) {
+      colDataAppendNULL(pCol, currentRow);
+      return pResInfo->numOfRes;
+    }
   }
 
+  SModeItem* pResItem = (SModeItem*)(pInfo->pItems + resIndex * (sizeof(SModeItem) + pInfo->colBytes));
+  colDataAppend(pCol, currentRow, pResItem->data, false);
+
   return pResInfo->numOfRes;
 }
 
+
 bool getTwaFuncEnv(struct SFunctionNode* pFunc, SFuncExecEnv* pEnv) {
   pEnv->calcMemSize = sizeof(STwaInfo);
   return true;