Re: POC: make mxidoff 64 bits

wenhui qiu <qiuwenhuifx@gmail.com>

From: wenhui qiu <qiuwenhuifx@gmail.com>

To: Heikki Linnakangas <hlinnaka@iki.fi>

Cc: Maxim Orlov <orlovmg@gmail.com>, Postgres hackers <pgsql-hackers@lists.postgresql.org>

Date: 2024-04-23T13:03:06Z

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 →

Fix partial read handling in pg_upgrade's multixact conversion
- ac94ce8194e5 19 (unreleased) landed
Increase timeout in multixid_conversion upgrade test
- bd43940b02b2 19 (unreleased) landed
Improve sanity checks on multixid members length
- ecb553ae8211 19 (unreleased) landed
Clarify comment on multixid offset wraparound check
- 170361d7b869 14.21 landed
- b0b52b7123ae 15.16 landed
- 7d42e2367c6b 16.12 landed
- cd1a887fe9bf 17.8 landed
- 3fbad030a24d 18.2 landed
- 366dcdaf5779 19 (unreleased) landed
Never store 0 as the nextMXact
- 87a350e1f284 19 (unreleased) landed
Add runtime checks for bogus multixact offsets
- d4b7bde4183b 19 (unreleased) landed
Widen MultiXactOffset to 64 bits
- bd8d9c9bdfa0 19 (unreleased) landed
Move pg_multixact SLRU page format definitions to a separate header
- bb3b1c4f6462 19 (unreleased) landed
Convert confusing macros in multixact.c to static inline functions
- 0099b9408e8c 17.0 landed
Index SLRUs by 64-bit integers rather than by 32-bit integers
- 4ed8f0913bfd 17.0 cited
Cope with possible failure of the oldest MultiXact to exist.
- b6a3444fa635 9.4.4 cited

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!

Best regards

On Tue, 23 Apr 2024 at 17:37, Heikki Linnakangas <hlinnaka@iki.fi> wrote:

> On 23/04/2024 11:23, Maxim Orlov wrote:
> > PROPOSAL
> > Make multixact offsets 64 bit.
>
> +1, this is a good next step and useful regardless of 64-bit XIDs.
>
> > @@ -156,7 +148,7 @@
> >               ((uint32) ((0xFFFFFFFF % MULTIXACT_MEMBERS_PER_PAGE) + 1))
> >
> >  /* page in which a member is to be found */
> > -#define MXOffsetToMemberPage(xid) ((xid) / (TransactionId)
> MULTIXACT_MEMBERS_PER_PAGE)
> > +#define MXOffsetToMemberPage(xid) ((xid) / (MultiXactOffset)
> MULTIXACT_MEMBERS_PER_PAGE)
> >  #define MXOffsetToMemberSegment(xid) (MXOffsetToMemberPage(xid) /
> SLRU_PAGES_PER_SEGMENT)
> >
> >  /* Location (byte offset within page) of flag word for a given member */
>
> 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.
>
> --
> Heikki Linnakangas
> Neon (https://neon.tech)
>
>
>
>