Re: [HACKERS] WAL logging problem in 9.4.3?

Hello. I added a fix for the defect 2.

At Wed, 25 Dec 2019 16:15:21 -0800, Noah Misch <noah(at)leadboat(dot)com> wrote in
> === Defect 2: Forgets to skip WAL due to oversimplification in heap_create()
>
> In ALTER TABLE cases where TryReuseIndex() avoided an index rebuild, we need
> to transfer WAL-skipped state to the new index relation. Before v24nm, the
> new index relation skipped WAL unconditionally. Since v24nm, the new index
> relation never skips WAL. I've added a test to alter_table.sql that reveals
> this problem under wal_level=minimal.

The fix for this defect utilizes the mechanism that preserves relcache
entry for dropped relation. If ATExecAddIndex can obtain such a
relcache entry for the old relation, it should hold the newness flags
and we can copy them to the new relcache entry. I added one member
named oldRelId to the struct IndexStmt to let the function access the
relcache entry for the old index relation.

I forgot to assing version 31 to the last patch, I reused the number
for this version.

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center