Re: Race conditions in logical decoding - Mailing list pgsql-hackers

On 2026-Sep-18, Antonin Houska wrote:

> Maybe I miss the point, but what's wrong about modifying the existing loop
> that inverts the meaning of the ->xip array
> 
>     /*
>      * snapbuild.c builds transactions in an "inverted" manner, which means it
>      * stores committed transactions in ->xip, not ones in progress. Build a
>      * classical snapshot by marking all non-committed transactions as
>      * in-progress. This can be expensive.
>      */
>     for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);)
>     {
>         ...
>     }
> 
> by calling XactLockTableWait() for each XID we find in the array (i.e. each
> committed transaction)?

Ah, you mean something like the attached quick POC?  This does pass the
two tests that Rui wrote, also attached.  (I didn't test Zhijie's, which
AFAICT is written to pass with the bug and fail without it.)

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Álvaro Herrera               48°01'N 7°57'E  —  https://www.EnterpriseDB.com/
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