enh(query): opt filter check.

source/dnode/vnode/src/meta/metaCache.c

@@ -549,12 +549,25 @@ int32_t metaUidFilterCachePut(SMeta* pMeta, uint64_t suid, const void* pKey, int
     tdListAppend(&p->list, pKey);
   } else {
     // check if it exists or not
+    size_t size = listNEles(&(*pEntry)->list);
+    if (size == 0) {
+      tdListAppend(&(*pEntry)->list, pKey);
+    } else if (size == 1) {
+      SListNode* pNode = listHead(&(*pEntry)->list);
+      uint64_t* p = (uint64_t*) pNode->data;
+      if (p[1] == ((uint64_t*)pKey)[1] && p[2] == ((uint64_t*)pKey)[2]) {
+        taosThreadMutexUnlock(pLock);
+        return TSDB_CODE_SUCCESS;
+      } else { // not equal, append it
+        tdListAppend(&(*pEntry)->list, pKey);
+      }
+    } else {  // more than one element
       SListIter iter = {0};
       tdListInitIter(&(*pEntry)->list, &iter, TD_LIST_FORWARD);
 
       SListNode* pNode = NULL;
       while ((pNode = tdListNext(&iter)) != NULL) {
-      uint64_t* p = (uint64_t*) pNode->data;
+        uint64_t* p = (uint64_t*)pNode->data;
 
         // key already exists in cache, quit
         if (p[1] == ((uint64_t*)pKey)[1] && p[2] == ((uint64_t*)pKey)[2]) {
@@ -565,6 +578,7 @@ int32_t metaUidFilterCachePut(SMeta* pMeta, uint64_t suid, const void* pKey, int
 
       tdListAppend(&(*pEntry)->list, pKey);
     }
+  }
 
   // add to cache.
   taosLRUCacheInsert(pCache, buf, sizeof(uint64_t) + keyLen, pPayload, payloadLen, freePayload, NULL,