Re: Remove custom redundant full page write description from GIN

Kirill Reshke <reshkekirill@gmail.com>

From: Kirill Reshke <reshkekirill@gmail.com>

To: Michael Paquier <michael@paquier.xyz>

Cc: Andrey Borodin <x4mmm@yandex-team.ru>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2025-10-09T12:33:54Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Improve description of some WAL records for GIN
- 138da727a174 19 (unreleased) landed
Add comment in ginxlog.h about block used with ginxlogInsertListPage
- 42c6b74d8928 19 (unreleased) landed
Remove block information from description of some WAL records for GIN
- 7072a8855e84 19 (unreleased) landed
Remove useless pointer update in ginxlog.c
- 3f431109dc63 19 (unreleased) landed

Attachments

v1-0001-Remove-all-fields-from-ginxlogSplit-except-flags.patch (application/octet-stream) patch v1-0001

On Wed, 8 Oct 2025 at 10:14, Michael Paquier <michael@paquier.xyz> wrote:
>
> On Tue, Oct 07, 2025 at 02:08:02PM +0500, Kirill Reshke wrote:
> > Turns out we already use XLogRecGetData in assignment:  char *rec =
> > XLogRecGetData(record). But I still did alter v2 patch a bit,
> > introducing new variable xlrec, to avoid clunky casts between char *
> > and ginxlogUpdateMeta.
>
> For UPDATE_META_PAGE, ntuples == 0 could also mean that we may show
> a lot of invalid block numbers, as well, which feels a bit pointless.
> I have switched that to check InvalidBlockNumber instead.

Thank you for pushing!

> While reviewing the whole, I have noticed that rightlink was missing
> for INSERT_LISTPAGE, as well as the right/left children pages for
> SPLIT.  I have added this information, applied the result.  Thanks!

After this change, I was wondering what is the purpose of
leftChildBlkno/rightChildBlkno fields of SPLIT record.
Turns out all of ginxlogSplit's fields except flags are of no use.
Should we remove them, reducing overall cognitive complexity of GIN
internals and reducing WAL footprint?

PFA patch for that. If this topic is too out-of-scope of this thread,
I can start another one, just let me know.

-- 
Best regards,
Kirill Reshke