From: Tom Lane <tgl@sss.pgh.pa.us>
To: Noah Misch <noah@leadboat.com>
cc: Peter Geoghegan <pg@bowt.ie>, Andres Freund <andres@anarazel.de>,
        Phil Florent <philflorent@hotmail.com>,
        PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Subject: Re: pgstat_report_activity() and parallel CREATE INDEX (was: Parallel
 index creation & pg_stat_activity)
In-reply-to: <20201025051836.GC2651494@rfd.leadboat.com>
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Comments: In-reply-to Noah Misch <noah@leadboat.com>
	message dated "Sat, 24 Oct 2020 22:18:36 -0700"
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Date: Sun, 25 Oct 2020 10:52:50 -0400
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Noah Misch <noah@leadboat.com> writes:
> On Sat, Oct 17, 2020 at 08:39:35AM -0700, Peter Geoghegan wrote:
>> I also prefer 2.

> Thanks.  Here is the pair of patches I plan to use.  The second is equiv=
alent
> to v0; I just added a log message.

The change in worker_spi_main seems a little weird/lazy.  I'd
be inclined to set and clear debug_query_string each time through
the loop, so that those operations are adjacent to the other
status-reporting operations, as they are in initialize_worker_spi.

I don't really like modifying a StringInfo while debug_query_string
is pointing at it, either.  Yeah, you'll *probably* get away with
that because the buffer is unlikely to move, but since the whole
exercise can only benefit crash-debugging scenarios, it'd be better
to be more paranoid.

One idea is to set debug_query_string immediately before each SPI_execute
and clear it just afterwards, rather than trying to associate it with
pgstat_report_activity calls.

			regards, tom lane