| From: | SATYANARAYANA NARLAPURAM <satyanarlapuram(at)gmail(dot)com> |
|---|---|
| To: | PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Álvaro Herrera <alvherre(at)kurilemu(dot)de>, Antonin Houska <ah(at)cybertec(dot)at> |
| Subject: | Possible premature SNAPBUILD_CONSISTENT with DB-specific running_xacts |
| Date: | 2026-04-19 18:58:46 |
| Message-ID: | CAHg+QDcQak4jx_6X2_Ws98rzG=xBARLjqm_=56wTRUtNsY4DZQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
Hi hackers,
A cluster-wide decoder must never have its snapshot-builder state changed
by a database-specific running_xacts record. Adding a check to return it
early.
I think otherwise a cluster wide decoder can potentially go to
SNAPSHOT_CONSISTENT state immediately even though transactions older
than nextXid are still in progress on a different DB (not tracked by
running_xact
record). This race is now possible with cluster wide decoders and Repack
concurrently run.
Attached a patch to fix this. Thoughts?
Thanks
Satya
| Attachment | Content-Type | Size |
|---|---|---|
| v1-snapbuild-only.patch | application/octet-stream | 1.3 KB |
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