Re: [HACKERS] WAL logging problem in 9.4.3?

Diffing the two latest versions of one patch:
> --- v32-0002-Fix-the-defect-1.patch 2020-01-18 14:32:47.499129940 -0800
> +++ v33-0002-Fix-the-defect-1.patch 2020-01-26 16:23:52.846391035 -0800
> +@@ -2978,8 +3054,8 @@ AssertPendingSyncs_RelationCache(void)
> + LOCKTAG_RELATION)
> + continue;
> + relid = ObjectIdGetDatum(locallock->tag.lock.locktag_field2);
> +- r = RelationIdGetRelation(relid);
> +- if (r == NULL)
> ++ r = RelationIdGetRelationCache(relid);

The purpose of this loop is to create relcache entries for rels locked in the
current transaction. (The "r == NULL" case happens for rels no longer visible
in catalogs. It is harmless.) Since RelationIdGetRelationCache() never
creates a relcache entry, calling it defeats that purpose.
RelationIdGetRelation() is the right function to call.

On Tue, Jan 21, 2020 at 06:45:57PM +0900, Kyotaro Horiguchi wrote:
> Three other fixes not mentined above are made. One is the useless
> rd_firstRelfilenodeSubid in the condition to dicide whether to
> preserve or not a relcache entry

It was not useless. Test case:

create table t (c int);
begin;
alter table t alter c type bigint; -- sets rd_firstRelfilenodeSubid
savepoint q; drop table t; rollback to q; -- forgets rd_firstRelfilenodeSubid
commit; -- assertion failure, after s/RelationIdGetRelationCache/RelationIdGetRelation/ discussed above