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base repository: postgresql-cfbot/postgresql
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base: cf/6037~1
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head repository: postgresql-cfbot/postgresql
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compare: cf/6037
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  • 2 commits
  • 1 file changed
  • 2 contributors

Commits on Dec 6, 2025

  1. Fix race condition when reading PredXact->SxactGlobalXmin 

    `DropAllPredicateLocksFromTable`, `PredicateLockPageSplit`, and
`CheckTableForSerializableConflictIn` all assume that
`!TransactionIdIsValid(PredXact->SxactGlobalXmin)` implies there are
no active serializable transactions.

This assumption is not true due to a race with
`SetNewSxactGlobalXmin`, which first sets `PredXact->SxactGlobalXmin`
to `InvalidTransactionId` then iterates over the active serializable
transactions to find the new xmin. If `SetNewSxactGlobalXmin` is
interrupted before setting a new xmin and other processes check
`!TransactionIdIsValid(PredXact->SxactGlobalXmin)` without taking a
lock during this time, they will incorrectly assume it is safe to
proceed as if there are no concurrent serializable transactions.
    @joshcurtis
    joshcurtis authored and Commitfest Bot committed Dec 6, 2025
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  2. [CF 6037] v1 - Fix race condition in SSI when reading PredXact->Sxact… 

    …GlobalXmin

This branch was automatically generated by a robot using patches from an
email thread registered at:

https://commitfest.postgresql.org/patch/6037

The branch will be overwritten each time a new patch version is posted to
the thread, and also periodically to check for bitrot caused by changes
on the master branch.

Patch(es): https://www.postgresql.org/message-id/CAEkjoh2X8yL9TKrQKx6SL6gtMNuZsyH8K-+rE78EwdOv4oXjSA@mail.gmail.com
Author(s): Josh Curtis
    Commitfest Bot committed Dec 6, 2025
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