fix review comment

Signed-off-by: Wei Liu <[email protected]>

internal/proxy/meta_cache.go

@@ -1072,7 +1072,7 @@ func (m *MetaCache) InvalidateShardLeaderCache(collections []int64) {
 			}
 		}
 		if len(dbInfo) == 0 {
-			delete(dbInfo, dbName)
+			delete(m.collLeader, dbName)
 		}
 	}
 }