| From: | "Anton A(dot) Melnikov" <a(dot)melnikov(at)postgrespro(dot)ru> |
|---|---|
| To: | PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Maybe don't process multi xmax in FreezeMultiXactId() if it is already marked as invalid? |
| Date: | 2024-06-18 06:57:11 |
| Message-ID: | fc43dd15-564b-4239-bc78-d0cc47b114d7@postgrespro.ru |
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| Lists: | pgsql-hackers |
On 14.06.2024 10:45, Anton A. Melnikov wrote:
> The src/backend/access/heap/README.tuplock says about HEAP_XMAX_INVALID bit
> that "Any tuple with this bit set does not have a valid value stored in XMAX."
>
> Found that FreezeMultiXactId() tries to process such an invalid multi xmax
> and may looks for an update xid in the pg_multixact for it.
>
> Maybe not do this work in FreezeMultiXactId() and exit immediately if the
> bit HEAP_XMAX_INVALID was already set?
>
Seems it is important to save the check that multi xmax is not behind relminmxid.
So saved it and correct README.tuplock accordingly.
Would be glad if someone take a look at the patch attached.
With the best regards,
--
Anton A. Melnikov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
| Attachment | Content-Type | Size |
|---|---|---|
| v1-0001-Dont-process-multi-xmax-in-the-FreezeMultiXactId.patch | text/x-patch | 1.7 KB |
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