From 379d574d7d51dbdbd3fa11d94ef92d0d789d6336 Mon Sep 17 00:00:00 2001
From: Bomin Zhang <bmzhang@taosdata.com>
Date: Fri, 4 Sep 2020 18:29:51 +0800
Subject: [PATCH] fix TD-1334: select count(*) returns wrong result

github #3334
---
 src/tsdb/src/tsdbRead.c | 59 ++++++++++++++++++++++++++++++++++++-----
 1 file changed, 52 insertions(+), 7 deletions(-)

diff --git a/src/tsdb/src/tsdbRead.c b/src/tsdb/src/tsdbRead.c
index ac7eba72b2..7e10e7c6d6 100644
--- a/src/tsdb/src/tsdbRead.c
+++ b/src/tsdb/src/tsdbRead.c
@@ -734,6 +734,10 @@ static int32_t doLoadFileDataBlock(STsdbQueryHandle* pQueryHandle, SCompBlock* p
   return TSDB_CODE_SUCCESS;
 }
 
+static int32_t copyDataFromFileBlock(STsdbQueryHandle* pQueryHandle, int32_t capacity, int32_t numOfRows, int32_t start, int32_t end);
+static void moveDataToFront(STsdbQueryHandle* pQueryHandle, int32_t numOfRows, int32_t numOfCols);
+static void doCheckGeneratedBlockRange(STsdbQueryHandle* pQueryHandle);
+
 static int32_t handleDataMergeIfNeeded(STsdbQueryHandle* pQueryHandle, SCompBlock* pBlock, STableCheckInfo* pCheckInfo){
   SQueryFilePos* cur = &pQueryHandle->cur;
   SDataBlockInfo binfo = GET_FILE_DATA_BLOCK_INFO(pCheckInfo, pBlock);
@@ -745,7 +749,6 @@ static int32_t handleDataMergeIfNeeded(STsdbQueryHandle* pQueryHandle, SCompBloc
   TSKEY key = (row != NULL)? dataRowKey(row):TSKEY_INITIAL_VAL;
   tsdbDebug("%p key in mem:%"PRId64", %p", pQueryHandle, key, pQueryHandle->qinfo);
 
-  cur->pos = ASCENDING_TRAVERSE(pQueryHandle->order)? 0:(binfo.rows-1);
 
   if ((ASCENDING_TRAVERSE(pQueryHandle->order) && (key != TSKEY_INITIAL_VAL && key <= binfo.window.ekey)) ||
       (!ASCENDING_TRAVERSE(pQueryHandle->order) && (key != TSKEY_INITIAL_VAL && key >= binfo.window.skey))) {
@@ -784,14 +787,54 @@ static int32_t handleDataMergeIfNeeded(STsdbQueryHandle* pQueryHandle, SCompBloc
      *
      * Here the buffer is not enough, so only part of file block can be loaded into memory buffer
      */
-    assert(pQueryHandle->outputCapacity >= binfo.rows);
-    pQueryHandle->realNumOfRows = binfo.rows;
+   assert(pQueryHandle->outputCapacity >= binfo.rows);
+
+    if ((cur->pos == 0 && ASCENDING_TRAVERSE(pQueryHandle->order)) ||
+        (cur->pos == (binfo.rows - 1) && (!ASCENDING_TRAVERSE(pQueryHandle->order)))) {
+      pQueryHandle->realNumOfRows = binfo.rows;
+
+      cur->rows = binfo.rows;
+      cur->win  = binfo.window;
+      cur->mixBlock = false;
+      cur->lastKey = ASCENDING_TRAVERSE(pQueryHandle->order)? (binfo.window.ekey + 1): (binfo.window.skey -1);
+    } else {
+
+      SDataCols* pCols = pQueryHandle->rhelper.pDataCols[0];
+      TSKEY* tsArray = pCols->cols[0].pData;
+
+      assert(pCols->cols[0].type == TSDB_DATA_TYPE_TIMESTAMP && pCols->cols[0].colId == PRIMARYKEY_TIMESTAMP_COL_INDEX &&
+             cur->pos >= 0 && cur->pos < pBlock->numOfRows &&
+             (tsArray[0] == binfo.window.skey && tsArray[binfo.rows - 1] == binfo.window.ekey));
+
+      if (ASCENDING_TRAVERSE(pQueryHandle->order)) {
+        cur->rows = binfo.rows - cur->pos;
+
+        cur->win.skey = tsArray[cur->pos];
+        cur->win.ekey = binfo.window.ekey;
+
+        cur->lastKey = binfo.window.ekey + 1;
+        int32_t numOfRows = copyDataFromFileBlock(pQueryHandle, pQueryHandle->outputCapacity, 0, cur->pos, binfo.rows-1);
+        assert(numOfRows == cur->rows);
+      } else {
+        cur->rows = cur->pos + 1;
+
+        cur->win.skey = binfo.window.skey;
+        cur->win.ekey = tsArray[cur->pos];
+
+        cur->lastKey = binfo.window.skey - 1;
+        int32_t numOfRows = copyDataFromFileBlock(pQueryHandle, pQueryHandle->outputCapacity, 0, 0, cur->pos);
+        assert(numOfRows == cur->rows);
+
+        int32_t numOfCols = (int32_t)(QH_GET_NUM_OF_COLS(pQueryHandle));
+        moveDataToFront(pQueryHandle, numOfRows, numOfCols);
+        doCheckGeneratedBlockRange(pQueryHandle);
+      }
+
+      pQueryHandle->realNumOfRows = cur->rows;
+      cur->mixBlock = true;
+    }
 
-    cur->rows = binfo.rows;
-    cur->win  = binfo.window;
-    cur->mixBlock = false;
     cur->blockCompleted = true;
-    cur->lastKey = binfo.window.ekey + (ASCENDING_TRAVERSE(pQueryHandle->order)? 1:-1);
     pCheckInfo->lastKey = cur->lastKey;
   }
 
@@ -823,6 +866,7 @@ static int32_t loadFileDataBlock(STsdbQueryHandle* pQueryHandle, SCompBlock* pBl
       assert(pCheckInfo->lastKey <= pBlock->keyLast);
       doMergeTwoLevelData(pQueryHandle, pCheckInfo, pBlock);
     } else {  // the whole block is loaded in to buffer
+      cur->pos = ASCENDING_TRAVERSE(pQueryHandle->order)? 0:(pBlock->numOfRows-1);
       code = handleDataMergeIfNeeded(pQueryHandle, pBlock, pCheckInfo);
     }
   } else {  //desc order, query ended in current block
@@ -842,6 +886,7 @@ static int32_t loadFileDataBlock(STsdbQueryHandle* pQueryHandle, SCompBlock* pBl
       assert(pCheckInfo->lastKey >= pBlock->keyFirst);
       doMergeTwoLevelData(pQueryHandle, pCheckInfo, pBlock);
     } else {
+      cur->pos = ASCENDING_TRAVERSE(pQueryHandle->order)? 0:(pBlock->numOfRows-1);
       code = handleDataMergeIfNeeded(pQueryHandle, pBlock, pCheckInfo);
     }
   }
-- 
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