fix: keep the stt iterator valid

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

@@ -792,7 +792,6 @@ typedef struct SLDataIter {
   SVersionRange          verRange;
   SSttBlockLoadInfo     *pBlockLoadInfo;
   bool                   ignoreEarlierTs;
-  bool                   bInit;
   struct SSttFileReader *pReader;
 } SLDataIter;
 

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

@@ -146,10 +146,8 @@ void *destroySttBlockReader(SArray *pLDataIterArray, int64_t *blocks, double *el
     SArray *pList = taosArrayGetP(pLDataIterArray, i);
     for (int32_t j = 0; j < taosArrayGetSize(pList); ++j) {
       SLDataIter *pIter = taosArrayGetP(pList, j);
-      if (pIter->bInit) {
-          *el += pIter->pBlockLoadInfo->elapsedTime;
-          *blocks += pIter->pBlockLoadInfo->loadBlocks;
-      }
+      *el += pIter->pBlockLoadInfo->elapsedTime;
+      *blocks += pIter->pBlockLoadInfo->loadBlocks;
       destroyLDataIter(pIter);
     }
     taosArrayDestroy(pList);
@@ -446,6 +444,13 @@ int32_t tLDataIterOpen2(struct SLDataIter *pIter, SSttFileReader *pSttFileReader
   pIter->pReader = pSttFileReader;
   pIter->pBlockLoadInfo = pBlockLoadInfo;
 
+  if (pIter->pReader == NULL) {
+    tsdbError("stt file reader is null, %s", idStr);
+    pIter->pSttBlk = NULL;
+    pIter->iSttBlk = -1;
+    return TSDB_CODE_SUCCESS;
+  }
+
   if (!pBlockLoadInfo->sttBlockLoaded) {
     int64_t st = taosGetTimestampUs();
 
@@ -837,7 +842,8 @@ int32_t tMergeTreeOpen2(SMergeTree *pMTree, SMergeTreeConf *pConf) {
 
         code = tsdbSttFileReaderOpen(pSttLevel->fobjArr->data[i]->fname, &conf, &pSttFileReader);
         if (code != TSDB_CODE_SUCCESS) {
-          return code;
+          tsdbError("open stt file reader error. file name %s, code %s, %s", pSttLevel->fobjArr->data[i]->fname,
+                    tstrerror(code), pMTree->idStr);
         }
       }
 
@@ -852,7 +858,7 @@ int32_t tMergeTreeOpen2(SMergeTree *pMTree, SMergeTreeConf *pConf) {
       if (code != TSDB_CODE_SUCCESS) {
         goto _end;
       }
-      pIter->bInit = true;
+      
       bool hasVal = tLDataIterNextRow(pIter, pMTree->idStr);
       if (hasVal) {
         tMergeTreeAddIter(pMTree, pIter);