fix: last cache read problem after schema change

source/dnode/vnode/src/inc/tsdb.h

@@ -766,6 +766,7 @@ typedef struct SCacheRowsReader {
   TdThreadMutex      readerMutex;
   SVnode            *pVnode;
   STSchema          *pSchema;
+  STSchema          *pCurrSchema;
   uint64_t           uid;
   uint64_t           suid;
   char             **transferBuf;  // todo remove it soon

source/dnode/vnode/src/tsdb/tsdbCache.c

@@ -1390,17 +1390,56 @@ _err:
   return code;
 }
 
-static int32_t mergeLast(tb_uid_t uid, STsdb *pTsdb, SArray **ppLastArray, SCacheRowsReader *pr) {
-  int32_t code = 0;
+static int32_t cloneTSchema(STSchema *pSrc, STSchema **ppDst) {
+  int32_t len = sizeof(STSchema) + sizeof(STColumn) * pSrc->numOfCols;
+  *ppDst = taosMemoryMalloc(len);
+  if (NULL == *ppDst) {
+    return TSDB_CODE_OUT_OF_MEMORY;
+  }
+  memcpy(*ppDst, pSrc, len);
+  return TSDB_CODE_SUCCESS;
+}
+
+static int32_t updateTSchema(int32_t sversion, SCacheRowsReader *pReader, uint64_t uid) {
+  if (NULL == pReader->pCurrSchema && sversion == pReader->pSchema->version) {
+    return cloneTSchema(pReader->pSchema, &pReader->pCurrSchema);
+  }
+
+  if (NULL != pReader->pCurrSchema && sversion == pReader->pCurrSchema->version) {
+    return TSDB_CODE_SUCCESS;
+  }
+
+  taosMemoryFreeClear(pReader->pCurrSchema);
+  return metaGetTbTSchemaEx(pReader->pTsdb->pVnode->pMeta, pReader->suid, uid, sversion, &pReader->pCurrSchema);
+}
+
+static int32_t initLastColArray(STSchema *pTSchema, SArray **ppColArray) {
+  SArray *pColArray = taosArrayInit(pTSchema->numOfCols, sizeof(SLastCol));
+  if (NULL == pColArray) {
+    return TSDB_CODE_OUT_OF_MEMORY;
+  }
 
+  for (int32_t i = 0; i < pTSchema->numOfCols; ++i) {
+    SLastCol col = {.ts = 0, .colVal = COL_VAL_NULL(pTSchema->columns[i].colId, pTSchema->columns[i].type)};
+    taosArrayPush(pColArray, &col);
+  }
+  *ppColArray = pColArray;
+  return TSDB_CODE_SUCCESS;
+}
+
+static int32_t mergeLast(tb_uid_t uid, STsdb *pTsdb, SArray **ppLastArray, SCacheRowsReader *pr) {
   STSchema *pTSchema = pr->pSchema;  // metaGetTbTSchema(pTsdb->pVnode->pMeta, uid, -1, 1);
-  int16_t   nCol = pTSchema->numOfCols;
-  int16_t   iCol = 0;
+  int16_t   nLastCol = pTSchema->numOfCols;
   int16_t   noneCol = 0;
   bool      setNoneCol = false;
-  SArray   *pColArray = taosArrayInit(nCol, sizeof(SLastCol));
+  SArray   *pColArray = NULL;
   SColVal  *pColVal = &(SColVal){0};
 
+  int32_t code = initLastColArray(pTSchema, &pColArray);
+  if (TSDB_CODE_SUCCESS != code) {
+    return code;
+  }
+
   TSKEY lastRowTs = TSKEY_MAX;
 
   CacheNextRowIter iter = {0};
@@ -1415,6 +1454,13 @@ static int32_t mergeLast(tb_uid_t uid, STsdb *pTsdb, SArray **ppLastArray, SCach
       break;
     }
 
+    code = updateTSchema(TSDBROW_SVERSION(pRow), pr, uid);
+    if (TSDB_CODE_SUCCESS != code) {
+      goto _err;
+    }
+    pTSchema = pr->pCurrSchema;
+    int16_t nCol = pTSchema->numOfCols;
+
     TSKEY rowTs = TSDBROW_TS(pRow);
 
     if (lastRowTs == TSKEY_MAX) {
@@ -1422,28 +1468,27 @@ static int32_t mergeLast(tb_uid_t uid, STsdb *pTsdb, SArray **ppLastArray, SCach
       STColumn *pTColumn = &pTSchema->columns[0];
 
       *pColVal = COL_VAL_VALUE(pTColumn->colId, pTColumn->type, (SValue){.val = lastRowTs});
-      if (taosArrayPush(pColArray, &(SLastCol){.ts = lastRowTs, .colVal = *pColVal}) == NULL) {
-        code = TSDB_CODE_OUT_OF_MEMORY;
-        goto _err;
-      }
+      taosArraySet(pColArray, 0, &(SLastCol){.ts = lastRowTs, .colVal = *pColVal});
 
-      for (iCol = 1; iCol < nCol; ++iCol) {
+      for (int16_t iCol = 1; iCol < nCol; ++iCol) {
+        if (iCol >= nLastCol) {
+          break;
+        }
+        SLastCol *pCol = taosArrayGet(pColArray, iCol);
+        if (pCol->colVal.cid != pTSchema->columns[iCol].colId) {
+          continue;
+        }
         tsdbRowGetColVal(pRow, pTSchema, iCol, pColVal);
 
-        SLastCol lastCol = {.ts = lastRowTs, .colVal = *pColVal};
+        *pCol = (SLastCol){.ts = lastRowTs, .colVal = *pColVal};
         if (IS_VAR_DATA_TYPE(pColVal->type) && pColVal->value.nData > 0) {
-          lastCol.colVal.value.pData = taosMemoryMalloc(lastCol.colVal.value.nData);
-          if (lastCol.colVal.value.pData == NULL) {
+          pCol->colVal.value.pData = taosMemoryMalloc(pCol->colVal.value.nData);
+          if (pCol->colVal.value.pData == NULL) {
             terrno = TSDB_CODE_OUT_OF_MEMORY;
             code = TSDB_CODE_OUT_OF_MEMORY;
             goto _err;
           }
-          memcpy(lastCol.colVal.value.pData, pColVal->value.pData, pColVal->value.nData);
-        }
-
-        if (taosArrayPush(pColArray, &lastCol) == NULL) {
-          code = TSDB_CODE_OUT_OF_MEMORY;
-          goto _err;
+          memcpy(pCol->colVal.value.pData, pColVal->value.pData, pColVal->value.nData);
         }
 
         if (!COL_VAL_IS_VALUE(pColVal) && !setNoneCol) {
@@ -1461,10 +1506,16 @@ static int32_t mergeLast(tb_uid_t uid, STsdb *pTsdb, SArray **ppLastArray, SCach
 
     // merge into pColArray
     setNoneCol = false;
-    for (iCol = noneCol; iCol < nCol; ++iCol) {
+    for (int16_t iCol = noneCol; iCol < nCol; ++iCol) {
+      if (iCol >= nLastCol) {
+        break;
+      }
       // high version's column value
       SLastCol *lastColVal = (SLastCol *)taosArrayGet(pColArray, iCol);
-      SColVal  *tColVal = &lastColVal->colVal;
+      if (lastColVal->colVal.cid != pTSchema->columns[iCol].colId) {
+        continue;
+      }
+      SColVal *tColVal = &lastColVal->colVal;
 
       tsdbRowGetColVal(pRow, pTSchema, iCol, pColVal);
       if (!COL_VAL_IS_VALUE(tColVal) && COL_VAL_IS_VALUE(pColVal)) {

source/dnode/vnode/src/tsdb/tsdbCacheRead.c

@@ -209,6 +209,8 @@ void* tsdbCacherowsReaderClose(void* pReader) {
     taosMemoryFree(p->pSchema);
   }
 
+  taosMemoryFree(p->pCurrSchema);
+
   destroyLastBlockLoadInfo(p->pLoadInfo);
 
   taosMemoryFree((void*)p->idstr);
@@ -303,7 +305,7 @@ int32_t tsdbRetrieveCacheRows(void* pReader, SSDataBlock* pResBlock, const int32
 
   for (int32_t i = 0; i < pr->pSchema->numOfCols; ++i) {
     struct STColumn* pCol = &pr->pSchema->columns[i];
-    SLastCol         p = {.ts = INT64_MIN, .colVal.type = pCol->type};
+    SLastCol         p = {.ts = INT64_MIN, .colVal.type = pCol->type, .colVal.flag = CV_FLAG_NULL};
 
     if (IS_VAR_DATA_TYPE(pCol->type)) {
       p.colVal.value.pData = taosMemoryCalloc(pCol->bytes, sizeof(char));