fix(query): fix bug in descending order scan in lastblock.

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

@@ -1315,7 +1315,7 @@ static bool fileBlockShouldLoad(STsdbReader* pReader, SFileDataBlockInfo* pFBloc
   // log the reason why load the datablock for profile
   if (loadDataBlock) {
     tsdbDebug("%p uid:%" PRIu64
-              " need to load the datablock, reason overlapwithneighborblock:%d, hasDup:%d, partiallyRequired:%d, "
+              " need to load the datablock, overlapwithneighborblock:%d, hasDup:%d, partiallyRequired:%d, "
               "overlapWithKey:%d, greaterThanBuf:%d, overlapWithDel:%d, overlapWithlastBlock:%d, %s",
               pReader, pFBlock->uid, overlapWithNeighbor, hasDup, partiallyRequired, overlapWithKey,
               moreThanOutputCapacity, overlapWithDel, overlapWithlastBlock, pReader->idStr);
@@ -2007,7 +2007,7 @@ static int32_t buildComposedDataBlockImpl(STsdbReader* pReader, STableBlockScanI
     if (pBlockData->nRow > 0) {
       TSDBROW fRow = tsdbRowFromBlockData(pBlockData, pDumpInfo->rowIndex);
 
-      // no last block
+      // no last block available, only data block exists
       if (pLastBlockReader->lastBlockData.nRow == 0 || (!hasDataInLastBlock(pLastBlockReader))) {
         if (tryCopyDistinctRowFromFileBlock(pReader, pBlockData, key, pDumpInfo)) {
           return TSDB_CODE_SUCCESS;
@@ -2028,38 +2028,10 @@ static int32_t buildComposedDataBlockImpl(STsdbReader* pReader, STableBlockScanI
 
       // row in last file block
       int64_t ts = getCurrentKeyInLastBlock(pLastBlockReader);
-      if (ts < key) {  // save rows in last block
+      ASSERT(ts >= key);
-        SBlockData* pLastBlockData = &pLastBlockReader->lastBlockData;
 
-        STSRow*    pTSRow = NULL;
+      if (ASCENDING_TRAVERSE(pReader->order)) {
-        SRowMerger merge = {0};
+        if (key < ts) {
-
-        TSDBROW fRow1 = tsdbRowFromBlockData(pLastBlockData, *pLastBlockReader->rowIndex);
-
-        tRowMergerInit(&merge, &fRow1, pReader->pSchema);
-        doMergeRowsInLastBlock(pLastBlockReader, pBlockScanInfo, ts, &merge);
-        tRowMergerGetRow(&merge, &pTSRow);
-
-        doAppendRowFromTSRow(pReader->pResBlock, pReader, pTSRow, pBlockScanInfo->uid);
-
-        taosMemoryFree(pTSRow);
-        tRowMergerClear(&merge);
-        return TSDB_CODE_SUCCESS;
-      } else if (ts == key) {
-        STSRow*    pTSRow = NULL;
-        SRowMerger merge = {0};
-
-        tRowMergerInit(&merge, &fRow, pReader->pSchema);
-        doMergeRowsInFileBlocks(pBlockData, pBlockScanInfo, pReader, &merge);
-        doMergeRowsInLastBlock(pLastBlockReader, pBlockScanInfo, ts, &merge);
-
-        tRowMergerGetRow(&merge, &pTSRow);
-        doAppendRowFromTSRow(pReader->pResBlock, pReader, pTSRow, pBlockScanInfo->uid);
-
-        taosMemoryFree(pTSRow);
-        tRowMergerClear(&merge);
-        return TSDB_CODE_SUCCESS;
-      } else {  // ts > key, asc; todo handle desc
           // imem & mem are all empty, only file exist
           if (tryCopyDistinctRowFromFileBlock(pReader, pBlockData, key, pDumpInfo)) {
             return TSDB_CODE_SUCCESS;
@@ -2076,6 +2048,43 @@ static int32_t buildComposedDataBlockImpl(STsdbReader* pReader, STableBlockScanI
             tRowMergerClear(&merge);
             return TSDB_CODE_SUCCESS;
           }
+        } else if (key == ts) {
+          STSRow*    pTSRow = NULL;
+          SRowMerger merge = {0};
+
+          tRowMergerInit(&merge, &fRow, pReader->pSchema);
+          doMergeRowsInFileBlocks(pBlockData, pBlockScanInfo, pReader, &merge);
+          doMergeRowsInLastBlock(pLastBlockReader, pBlockScanInfo, ts, &merge);
+
+          tRowMergerGetRow(&merge, &pTSRow);
+          doAppendRowFromTSRow(pReader->pResBlock, pReader, pTSRow, pBlockScanInfo->uid);
+
+          taosMemoryFree(pTSRow);
+          tRowMergerClear(&merge);
+          return TSDB_CODE_SUCCESS;
+        } else {
+          ASSERT(0);
+          return TSDB_CODE_SUCCESS;
+        }
+      } else {  // desc order
+        SBlockData* pLastBlockData = &pLastBlockReader->lastBlockData;
+        TSDBROW fRow1 = tsdbRowFromBlockData(pLastBlockData, *pLastBlockReader->rowIndex);
+
+        STSRow*    pTSRow = NULL;
+        SRowMerger merge = {0};
+        tRowMergerInit(&merge, &fRow1, pReader->pSchema);
+        doMergeRowsInLastBlock(pLastBlockReader, pBlockScanInfo, ts, &merge);
+
+        if (ts == key) {
+          doMergeRowsInFileBlocks(pBlockData, pBlockScanInfo, pReader, &merge);
+        }
+
+        tRowMergerGetRow(&merge, &pTSRow);
+        doAppendRowFromTSRow(pReader->pResBlock, pReader, pTSRow, pBlockScanInfo->uid);
+
+        taosMemoryFree(pTSRow);
+        tRowMergerClear(&merge);
+        return TSDB_CODE_SUCCESS;
       }
     } else {  // only last block exists
       SBlockData* pLastBlockData = &pLastBlockReader->lastBlockData;
@@ -2575,6 +2584,14 @@ static int32_t doBuildDataBlock(STsdbReader* pReader) {
     // todo rows in buffer should be less than the file block in asc, greater than file block in desc
     int64_t endKey = (ASCENDING_TRAVERSE(pReader->order)) ? pBlock->minKey.ts : pBlock->maxKey.ts;
     code = buildDataBlockFromBuf(pReader, pScanInfo, endKey);
+  } else {
+    if (hasDataInLastBlock(pLastBlockReader) && !ASCENDING_TRAVERSE(pReader->order)) {
+      // only return the rows in last block
+      int64_t tsLast = getCurrentKeyInLastBlock(pLastBlockReader);
+      ASSERT (tsLast >= pBlock->maxKey.ts);
+      tBlockDataReset(&pReader->status.fileBlockData);
+
+      code = buildComposedDataBlock(pReader);
     } else {   // whole block is required, return it directly
       SDataBlockInfo* pInfo = &pReader->pResBlock->info;
       pInfo->rows = pBlock->nRow;
@@ -2583,6 +2600,7 @@ static int32_t doBuildDataBlock(STsdbReader* pReader) {
       setComposedBlockFlag(pReader, false);
       setBlockAllDumped(&pStatus->fBlockDumpInfo, pBlock->maxKey.ts, pReader->order);
     }
+  }
 
   return code;
 }