fix: after the last cache is created, modify the schema and query again, resulting in taosd crash

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

@@ -38,16 +38,17 @@ static int32_t saveOneRow(SArray* pRow, SSDataBlock* pBlock, SCacheRowsReader* p
         *(int64_t*)p->buf = pColVal->ts;
         allNullRow = false;
       } else {
-        int32_t   slotId = slotIds[i];
-        SLastCol* pColVal = (SLastCol*)taosArrayGet(pRow, slotId);
-
+        int32_t slotId = slotIds[i];
         // add check for null value, caused by the modification of table schema (new column added).
-        if (pColVal == NULL) {
+        if (slotId >= taosArrayGetSize(pRow)) {
           p->ts = 0;
           p->isNull = true;
+          colDataSetNULL(pColInfoData, numOfRows);
           continue;
         }
 
+        SLastCol* pColVal = (SLastCol*)taosArrayGet(pRow, slotId);
+
         p->ts = pColVal->ts;
         p->isNull = !COL_VAL_IS_VALUE(&pColVal->colVal);
         allNullRow = p->isNull & allNullRow;

source/libs/function/src/builtinsimpl.c

@@ -2461,6 +2461,9 @@ static int32_t firstLastFunctionMergeImpl(SqlFunctionCtx* pCtx, bool isFirstQuer
   int32_t numOfElems = 0;
 
   for (int32_t i = start; i < start + pInput->numOfRows; ++i) {
+    if (colDataIsNull_s(pCol, i)) {
+      continue;
+    }
     char*          data = colDataGetData(pCol, i);
     SFirstLastRes* pInputInfo = (SFirstLastRes*)varDataVal(data);
     int32_t        code = firstLastTransferInfo(pCtx, pInputInfo, pInfo, isFirstQuery, i);