On Wed, Sep 14, 2022 at 6:33 PM Amit Kapila <amit.kapil...@gmail.com> wrote: > > On Fri, Sep 9, 2022 at 6:18 AM Masahiko Sawada <sawada.m...@gmail.com> wrote: > > > > Updated the patch accordingly. > > > > I have created two xacts each with savepoints and after your patch, > the record will show xacts/subxacts information as below: > > rmgr: Standby len (rec/tot): 74/ 74, tx: 0, lsn: > 0/014AC238, prev 0/014AC1F8, desc: RUNNING_XACTS nextXid 733 > latestCompletedXid 726 oldestRunningXid 727; 2 xacts: 729 727; 4 > subxacts: 730 731 728 732 > > There is no way to associate which subxacts belong to which xact, so > will it be useful, and if so, how? I guess we probably don't need it > here because the describe records just display the record information.
I think it's useful for debugging purposes. For instance, when I was working on the fix 68dcce247f1a13318613a0e27782b2ca21a4ceb7 (REL_14_STABLE), I checked if all initial running transactions including subtransactions are properly stored and purged by checking the debug logs and pg_waldump output. Actually, until I realize that the description of RUNNING_XACTS doesn't show subtransaction information, I was confused by the fact that the saved initial running transactions didn't match the description shown by pg_waldump. Regards, -- Masahiko Sawada PostgreSQL Contributors Team RDS Open Source Databases Amazon Web Services: https://aws.amazon.com
