Re: executor relation handling

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Andres Freund <andres(at)anarazel(dot)de>, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Jesper Pedersen <jesper(dot)pedersen(at)redhat(dot)com>, Amit Langote <amitlangote09(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: executor relation handling
Date: 2018-10-04 19:57:40
Message-ID: CA+TgmoZ9DBSqq2Oyk+w9u3gLBhzncCuB6_nfS5DKsq7PNDRpaw@mail.gmail.com
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On Thu, Oct 4, 2018 at 3:28 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> I'm possibly confused, but I thought that the design of parallel query
> involved an expectation that workers didn't need to get their own locks.

You are, indeed, confused. A heck of a lot of effort went into making
sure that the workers COULD take their own locks, and into trying to
make sure that didn't break anything. That effort may or may not have
been entirely successful, but I'm pretty sure that having them NOT
take locks is going to be a lot worse.

> What we've determined so far in this thread is that workers *do* get
> their own locks (or did before yesterday), but I'd been supposing that
> that was accidental not intentional.

Nope, that was intentional.

> In any case, I definitely intend that they will be getting their own
> locks again after the dust has settled. Panic not.

/me unloads metaphorical bazooka.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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