From 52babbd1381cfe7b3e2e3d7ce74372434644545a Mon Sep 17 00:00:00 2001
From: Minglei Jin <stephenk@gmx.us>
Date: Wed, 6 Apr 2022 19:59:07 +0800
Subject: [PATCH] [TS-510]<fix>: fix missing last_row results

---
 src/tsdb/src/tsdbRead.c | 43 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/src/tsdb/src/tsdbRead.c b/src/tsdb/src/tsdbRead.c
index 4f47d9d7b2..e559839e3e 100644
--- a/src/tsdb/src/tsdbRead.c
+++ b/src/tsdb/src/tsdbRead.c
@@ -189,6 +189,8 @@ static void*   destroyTableCheckInfo(SArray* pTableCheckInfo);
 static bool    tsdbGetExternalRow(TsdbQueryHandleT pHandle);
 static int32_t tsdbQueryTableList(STable* pTable, SArray* pRes, void* filterInfo);
 static STableBlockInfo* moveToNextDataBlockInCurrentFile(STsdbQueryHandle* pQueryHandle);
+static bool initTableMemIterator(STsdbQueryHandle* pHandle, STableCheckInfo* pCheckInfo);
+static SMemRow getSMemRowInTableMem(STableCheckInfo* pCheckInfo, int32_t order, int32_t update, SMemRow* extraRow);
 
 static void tsdbInitDataBlockLoadInfo(SDataBlockLoadInfo* pBlockLoadInfo) {
   pBlockLoadInfo->slot = -1;
@@ -632,12 +634,53 @@ static int32_t lazyLoadCacheLast(STsdbQueryHandle* pQueryHandle) {
     if (pTable->cacheLastConfigVersion == pRepo->cacheLastConfigVersion) {
       continue;
     }
+
+    if (!pCheckInfo->initBuf) {
+      initTableMemIterator(pQueryHandle, pCheckInfo);
+    }
+
     code = tsdbLoadLastCache(pRepo, pTable);
     if (code != 0) {
       tsdbError("%p uid:%" PRId64 ", tid:%d, failed to load last cache since %s", pQueryHandle, pTable->tableId.uid,
                 pTable->tableId.tid, tstrerror(terrno));
       break;
     }
+
+    STsdbCfg *pCfg = &pQueryHandle->pTsdb->config;
+    bool cacheLastRow = CACHE_LAST_ROW(&(pRepo->config));
+    if (!cacheLastRow) continue;
+
+    SMemRow row = getSMemRowInTableMem(pCheckInfo, pQueryHandle->order, pCfg->update, NULL);
+    if (row == NULL) continue;
+    TSKEY key = memRowKey(row);
+
+    if (!pTable->lastRow) {
+      STSchema *pSchema = tsdbGetTableSchema(pTable);
+      SMemRow   lastRow = taosTMalloc(memRowMaxBytesFromSchema(pSchema));
+      if (lastRow == NULL) {
+        return TSDB_CODE_TDB_OUT_OF_MEMORY;
+      }
+
+      memRowCpy(lastRow, row);
+      pTable->lastRow = lastRow;
+      pTable->lastKey = key;
+    } else {
+      TSKEY lastRowKey = memRowKey(pTable->lastRow);
+      if (key <= lastRowKey) continue;
+
+      if (memRowTLen(pTable->lastRow) < memRowTLen(row)) {
+	SMemRow lastRow = taosTRealloc(pTable->lastRow, memRowTLen(row));
+        if (lastRow == NULL) {
+          taosTZfree(pTable->lastRow);
+          pTable->lastRow = NULL;
+
+          return TSDB_CODE_TDB_OUT_OF_MEMORY;
+        }
+	pTable->lastRow = lastRow;
+      }
+      memRowCpy(pTable->lastRow, row);
+      pTable->lastKey = key;
+    }
   }
 
   return code;
-- 
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