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Re: RFC: Logging plan of the running query

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Andrei Lepikhov <lepihov@gmail.com>
Cc: torikoshia <torikoshia@oss.nttdata.com>, Lukas Fittl <lukas@fittl.com>, pgsql-hackers@lists.postgresql.org, Atsushi Torikoshi <torikoshia.tech@gmail.com>, samimseih@gmail.com, destrex271@gmail.com
Date: 2026-06-26T12:50:56Z
Lists: pgsql-hackers 
On Thu, Jun 25, 2026 at 6:33 AM Andrei Lepikhov <lepihov@gmail.com> wrote:
> Ok, so just mention this behaviour in the documentation - let people know that
> they should potentially wait for a minute or two more to see the EXPLAIN.
> Real-life with huge queries and big machines provide us with examples where a
> backend might delay a response to a signal for quite a substantial time.
>
> Sometimes nothing happens after such an async operation, and we need to identify
> the problem: has the backend stalled, is the ‘logging plan’ algorithm
> ineffective, or is something else happening?

I don't think we document this in other, similar cases. Many things
can be delayed if the machine is overloaded, but unless I am missing
something, having to wait over a minute for this to work would be
*extremely* unusual and only happen in case of a machine that is
absolutely being crushed by the load. And in that case everything else
will be slow, too.

-- 
Robert Haas
EDB: http://www.enterprisedb.com

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  1. ecpg: Catch zero-length Unicode identifiers correctly

  2. Improve warning message in pg_signal_backend()

  3. Add assert to ensure that page locks don't participate in deadlock cycle.