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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Maxim Boguk <maxim.boguk@gmail.com>
Cc: David Rowley <dgrowleyml@gmail.com>
Cc: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #18588: Cannot force/let database use parallel execution in simple case.
Date: Thu, 22 Aug 2024 16:52:43 -0400
Message-ID: <2074136.1724359963@sss.pgh.pa.us> (raw)
In-Reply-To: <CAK-MWwRK4BYqEn-SxoMSb5iFr+fhTuKgS5kFrH=awPTrYDEtpg@mail.gmail.com>
References: <18588-204730f9394441a8@postgresql.org>
	<CAApHDvqGgO7c8N0kq5H4jZ0NZe=NGZDo4VVF5Fi5CVdJNbvStg@mail.gmail.com>
	<CAK-MWwTqDRerxrpaN8Xb25DqDGBw1UT+YSkfp4QN-MgOH97c+Q@mail.gmail.com>
	<CAK-MWwS_ZAsaGrz0byqCO38NNrNqPkNt1ww1dorHz_wiaFbWvw@mail.gmail.com>
	<2059550.1724353316@sss.pgh.pa.us>
	<CAK-MWwRK4BYqEn-SxoMSb5iFr+fhTuKgS5kFrH=awPTrYDEtpg@mail.gmail.com>

Maxim Boguk <maxim.boguk@gmail.com> writes:
> With sufficiently large table - I didn't manage find a combinations of
> settings to force parallel execution (im my real case - the database huge
> and mostly cold on ssd raid - so parallel execution provides almost linear
> speedup with amount of parallel workers even on 1000 rows... not talking
> about 10k-10m rows, but I cannot convince the PostgreSQL use parallel index
> scan for 2m returned rows case).

Well, there may be something going on in your real case that isn't
apparent from this toy example.  Perhaps look for a better example?

			regards, tom lane





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