feat: tag read

include/common/tdataformat.h

@@ -384,7 +384,7 @@ static FORCE_INLINE int32_t comparTagId(const void *key1, const void *key2) {
   }
 }
 
-static FORCE_INLINE void *tdGetKVRowValOfCol(SKVRow row, int16_t colId) {
+static FORCE_INLINE void *tdGetKVRowValOfCol(const SKVRow row, int16_t colId) {
   void *ret = taosbsearch(&colId, kvRowColIdx(row), kvRowNCols(row), sizeof(SColIdx), comparTagId, TD_EQ);
   if (ret == NULL) return NULL;
   return kvRowColVal(row, (SColIdx *)ret);

source/dnode/vnode/inc/vnode.h

@@ -72,10 +72,11 @@ typedef struct SMeta       SMeta;  // todo: remove
 typedef struct SMetaReader SMetaReader;
 typedef struct SMetaEntry  SMetaEntry;
 
-void metaReaderInit(SMetaReader *pReader, SMeta *pMeta, int32_t flags);
-void metaReaderClear(SMetaReader *pReader);
-int  metaGetTableEntryByUid(SMetaReader *pReader, tb_uid_t uid);
-int  metaReadNext(SMetaReader *pReader);
+void        metaReaderInit(SMetaReader *pReader, SMeta *pMeta, int32_t flags);
+void        metaReaderClear(SMetaReader *pReader);
+int         metaGetTableEntryByUid(SMetaReader *pReader, tb_uid_t uid);
+int         metaReadNext(SMetaReader *pReader);
+const void *metaGetTableTagVal(SMetaEntry *pEntry, int16_t cid);
 
 #if 1  // refact APIs below (TODO)
 typedef SVCreateTbReq   STbCfg;

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

@@ -466,3 +466,8 @@ void *metaGetSmaInfoByIndex(SMeta *pMeta, int64_t indexUid, bool isDecode) {
 }
 
 #endif
+
+const void *metaGetTableTagVal(SMetaEntry *pEntry, int16_t cid) {
+  ASSERT(pEntry->type == TSDB_CHILD_TABLE);
+  return tdGetKVRowValOfCol((const SKVRow)pEntry->ctbEntry.pTags, cid);
+}
\ No newline at end of file