diff --git a/src/system/detail/src/vnodeCache.c b/src/system/detail/src/vnodeCache.c
index 94ac006060c83785f24ced70bddd4269105a2b7d..45596ff5539f02a9ba5e1cb961d7f10c8aad61f2 100644
--- a/src/system/detail/src/vnodeCache.c
+++ b/src/system/detail/src/vnodeCache.c
@@ -172,6 +172,7 @@ int vnodeFreeCacheBlock(SCacheBlock *pCacheBlock) {
     SCachePool *pPool = (SCachePool *)vnodeList[pObj->vnode].pCachePool;
     if (pCacheBlock->notFree) {
       pPool->notFreeSlots--;
+      pInfo->unCommittedBlocks--;
       dTrace("vid:%d sid:%d id:%s, cache block is not free, slot:%d, index:%d notFreeSlots:%d",
              pObj->vnode, pObj->sid, pObj->meterId, pCacheBlock->slot, pCacheBlock->index, pPool->notFreeSlots);
     }
diff --git a/src/system/detail/src/vnodeImport.c b/src/system/detail/src/vnodeImport.c
index 260d5312002880d8396a032049355933a05d6eb2..0d3cd2b338574dc4c7256fbbcbcf8fd86db62950 100644
--- a/src/system/detail/src/vnodeImport.c
+++ b/src/system/detail/src/vnodeImport.c
@@ -479,7 +479,7 @@ int vnodeImportToFile(SImportInfo *pImport) {
         slot = (slot + 1 + pInfo->maxBlocks) % pInfo->maxBlocks;
       }
 
-      // last slot, the uncommitted slots shall be shifted
+      // last slot, the uncommitted slots shall be shifted, a cache block may have empty rows
       SCacheBlock *pCacheBlock = pInfo->cacheBlocks[slot];
       int          points = pCacheBlock->numOfPoints - pInfo->commitPoint;
       if (points > 0) {
@@ -568,7 +568,7 @@ int vnodeImportToCache(SImportInfo *pImport, char *payload, int rows) {
     }
   }
 
-  // copy the overwritten data into buffer
+  // copy the overwritten data into buffer, merge cache blocks
   tpoints = rows;
   pos = pImport->pos;
   slot = pImport->slot;
@@ -603,6 +603,19 @@ int vnodeImportToCache(SImportInfo *pImport, char *payload, int rows) {
     pos = 0;
     tpoints -= points;
 
+    if (tpoints == 0) {
+      // free the rest of cache blocks, since cache blocks are merged
+      int currentSlot = slot;
+      while (slot != pInfo->currentSlot) {
+        slot = (slot + 1) % pInfo->maxBlocks;
+        pCacheBlock = pInfo->cacheBlocks[slot];
+        vnodeFreeCacheBlock(pCacheBlock);
+      }
+
+      pInfo->currentSlot = currentSlot;
+      slot = currentSlot; // make sure to exit from the while loop
+    }
+
     if (slot == pInfo->currentSlot) break;
     slot = (slot + 1) % pInfo->maxBlocks;
   }