!5828 物化视图功能增强，补齐功能，包括支持删除操作

Merge pull request !5828 from TinyBag/matview

src/include/utils/rel.h

@@ -292,6 +292,7 @@ typedef struct RelationData {
     /* double linked list node, partition and bucket relation would be stored in fakerels list of resource owner */
     dlist_node node;
 
+    /* only valid if has mlog and used by incremental matview */
     Oid rd_mlogoid;
     /* Is under the context of creating crossbucket index? */
     bool newcbi;