Horton

Re: xact_start for walsender & logical decoding not updated

Alvaro Herrera <alvherre@2ndquadrant.com>

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From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Tomas Vondra <tomas.vondra@2ndquadrant.com>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, craig@2ndquadrant.com, pgsql-hackers@postgresql.org
Date: 2020-01-07T23:52:34Z
Lists: pgsql-hackers

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On 2020-Jan-07, Tom Lane wrote:

> I wrote:
> > The buildfarm seems less than happy with this.
> 
> ... and, having now looked at the patch, I'm not surprised.
> Breaking stmtStartTimestamp, which is what you did, seems like
> an awfully side-effect-filled route to the goal.  If you want
> to prevent monitoring from showing this, why didn't you just
> prevent monitoring from showing it?  That is, I'd have expected
> some am_walsender logic in or near pgstat.c, not here.

That seems a pretty simple patch; attached (untested).  However, my
patch seemed a pretty decent way to achieve the goal, and I don't
understand why it causes the failure, or indeed why we care about
stmtStartTimestamp at all.  I'll look into this again tomorrow.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. Reimplement nullification of walsender timestamp

  2. pg_stat_activity: show NULL stmt start time for walsenders