fix(query): set correct last value.

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

@@ -162,7 +162,7 @@ static int32_t doExtractCacheRow(SCacheRowsReader* pr, SLRUCache* lruCache, uint
   int32_t code = TSDB_CODE_SUCCESS;
   *pRow = NULL;
 
-  if ((pr->type & CACHESCAN_RETRIEVE_LAST_ROW) == CACHESCAN_RETRIEVE_LAST_ROW) {
+  if (HASTYPE(pr->type, CACHESCAN_RETRIEVE_LAST_ROW)) {
     code = tsdbCacheGetLastrowH(lruCache, uid, pr->pVnode->pTsdb, h);
   } else {
     code = tsdbCacheGetLastH(lruCache, uid, pr->pVnode->pTsdb, h);
@@ -231,7 +231,7 @@ int32_t tsdbRetrieveCacheRows(void* pReader, SSDataBlock* pResBlock, const int32
   }
 
   // retrieve the only one last row of all tables in the uid list.
-  if ((pr->type & CACHESCAN_RETRIEVE_TYPE_SINGLE) == CACHESCAN_RETRIEVE_TYPE_SINGLE) {
+  if (HASTYPE(pr->type, CACHESCAN_RETRIEVE_TYPE_SINGLE)) {
     for (int32_t i = 0; i < numOfTables; ++i) {
       STableKeyInfo* pKeyInfo = taosArrayGet(pr->pTableList, i);
 
@@ -255,6 +255,15 @@ int32_t tsdbRetrieveCacheRows(void* pReader, SSDataBlock* pResBlock, const int32
               hasRes = true;
               p->ts = pCol->ts;
               p->colVal = pCol->colVal;
+
+              // only set value for last row query
+              if (HASTYPE(pr->type, CACHESCAN_RETRIEVE_LAST_ROW)) {
+                if (taosArrayGetSize(pTableUidList) == 0) {
+                  taosArrayPush(pTableUidList, &pKeyInfo->uid);
+                } else {
+                  taosArraySet(pTableUidList, 0, &pKeyInfo->uid);
+                }
+              }
             }
           } else {
             SLastCol* p = taosArrayGet(pLastCols, slotId);
@@ -268,15 +277,12 @@ int32_t tsdbRetrieveCacheRows(void* pReader, SSDataBlock* pResBlock, const int32
               hasRes = true;
               p->ts = pColVal->ts;
 
-              if (COL_VAL_IS_VALUE(&pColVal->colVal)) {
-                if (IS_VAR_DATA_TYPE(pColVal->colVal.type)) {
-                  uint8_t* px = p->colVal.value.pData;
-                  p->colVal = pColVal->colVal;
-                  p->colVal.value.pData = px;
-                  memcpy(px, pColVal->colVal.value.pData, pColVal->colVal.value.nData);
-                } else {
-                  p->colVal = pColVal->colVal;
-                }
+              uint8_t* px = p->colVal.value.pData;
+              p->colVal = pColVal->colVal;
+
+              if (COL_VAL_IS_VALUE(&pColVal->colVal) && IS_VAR_DATA_TYPE(pColVal->colVal.type)) {
+                p->colVal.value.pData = px;
+                memcpy(px, pColVal->colVal.value.pData, pColVal->colVal.value.nData);
               }
             }
           }
@@ -290,7 +296,7 @@ int32_t tsdbRetrieveCacheRows(void* pReader, SSDataBlock* pResBlock, const int32
       saveOneRow(pLastCols, pResBlock, pr, slotIds, pRes);
     }
 
-  } else if ((pr->type & CACHESCAN_RETRIEVE_TYPE_ALL) == CACHESCAN_RETRIEVE_TYPE_ALL) {
+  } else if (HASTYPE(pr->type, CACHESCAN_RETRIEVE_TYPE_ALL)) {
     for (int32_t i = pr->tableIndex; i < numOfTables; ++i) {
       STableKeyInfo* pKeyInfo = taosArrayGet(pr->pTableList, i);
       code = doExtractCacheRow(pr, lruCache, pKeyInfo->uid, &pRow, &h);

source/libs/executor/src/cachescanoperator.c

@@ -193,20 +193,23 @@ SSDataBlock* doScanCache(SOperatorInfo* pOperator) {
       pInfo->currentGroupIndex += 1;
 
       // check for tag values
-      // TODO NOTE: The uid of pInfo->pRes is required.
       if (pInfo->pRes->info.rows > 0) {
         if (pInfo->pseudoExprSup.numOfExprs > 0) {
           SExprSupp* pSup = &pInfo->pseudoExprSup;
-          pInfo->pRes->info.uid = *(tb_uid_t*)taosArrayGet(pInfo->pUidList, 0);
 
           STableKeyInfo* pKeyInfo = taosArrayGet(pGroupTableList, 0);
           pInfo->pRes->info.groupId = pKeyInfo->groupId;
 
-          code = addTagPseudoColumnData(&pInfo->readHandle, pSup->pExprInfo, pSup->numOfExprs, pInfo->pRes,
-                                        GET_TASKID(pTaskInfo));
-          if (code != TSDB_CODE_SUCCESS) {
-            pTaskInfo->code = code;
-            return NULL;
+          if (taosArrayGetSize(pInfo->pUidList) > 0) {
+            ASSERT((pInfo->retrieveType & CACHESCAN_RETRIEVE_LAST_ROW) == CACHESCAN_RETRIEVE_LAST_ROW);
+
+            pInfo->pRes->info.uid = *(tb_uid_t*)taosArrayGet(pInfo->pUidList, 0);
+            code = addTagPseudoColumnData(&pInfo->readHandle, pSup->pExprInfo, pSup->numOfExprs, pInfo->pRes,
+                                          GET_TASKID(pTaskInfo));
+            if (code != TSDB_CODE_SUCCESS) {
+              pTaskInfo->code = code;
+              return NULL;
+            }
           }
         }
 

tests/system-test/2-query/last_row.py

@@ -13,7 +13,7 @@ class TDTestCase:
 
     def init(self, conn, logSql):
         tdLog.debug(f"start to excute {__file__}")
-        tdSql.init(conn.cursor(), False)
+        tdSql.init(conn.cursor(), True)
         self.tb_nums = 10
         self.row_nums = 20
         self.ts = 1434938400000