Horton

Re: POC: make mxidoff 64 bits

Maxim Orlov <orlovmg@gmail.com>

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From: Maxim Orlov <orlovmg@gmail.com>
To: wenhui qiu <qiuwenhuifx@gmail.com>
Cc: Heikki Linnakangas <hlinnaka@iki.fi>, Postgres hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-04-25T14:20:53Z
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 →

  1. Fix partial read handling in pg_upgrade's multixact conversion

  2. Increase timeout in multixid_conversion upgrade test

  3. Improve sanity checks on multixid members length

  4. Clarify comment on multixid offset wraparound check

  5. Never store 0 as the nextMXact

  6. Add runtime checks for bogus multixact offsets

  7. Widen MultiXactOffset to 64 bits

  8. Move pg_multixact SLRU page format definitions to a separate header

  9. Convert confusing macros in multixact.c to static inline functions

  10. Index SLRUs by 64-bit integers rather than by 32-bit integers

  11. Cope with possible failure of the oldest MultiXact to exist.

On Tue, 23 Apr 2024 at 12:37, Heikki Linnakangas <hlinnaka@iki.fi> wrote:

> This is really a bug fix. It didn't matter when TransactionId and
> MultiXactOffset were both typedefs of uint32, but it was always wrong.
> The argument name 'xid' is also misleading.
>
> I think there are some more like that, MXOffsetToFlagsBitShift for example.

Yeah, I always thought so too.  I believe, this is just a copy-paste.  You
mean, it is worth creating a separate CF
entry for these fixes?


On Tue, 23 Apr 2024 at 16:03, Andrey M. Borodin <x4mmm@yandex-team.ru>
wrote:

> BTW as a side note... I see lot's of casts to (unsigned long long), can't
> we just cast to MultiXactOffset?
>
Actually, first versions of the 64xid patch set have such a cast to types
TransactionID, MultiXact and so on.  But,
after some discussions, we are switched to unsigned long long cast.
Unfortunately, I could not find an exact link
for that discussion.  On the other hand, such a casting is already used
throughout the code.  So, just for the
sake of the consistency, I would like to stay with these casts.


On Tue, 23 Apr 2024 at 16:03, wenhui qiu <qiuwenhuifx@gmail.com> wrote:

> Hi Maxim Orlov
>    Thank you so much for your tireless work on this. Increasing the WAL
> size by a few bytes should have very little impact with today's disk
> performance(Logical replication of this feature wal log is also increased a
> lot, logical replication is a milestone new feature, and the community has
> been improving the logical replication of functions),I believe removing
> troubled postgresql Transaction ID Wraparound was also a milestone  new
> feature  adding a few bytes is worth it!
>
I'm 100% agree.  Maybe, I should return to this approach and find some
benefits for having FXIDs in WAL.