From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Michael Paquier <michael@paquier.xyz>
Cc: Tsunakawa, Takayuki <tsunakawa.takay@jp.fujitsu.com>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: removal of dangling temp tables
Date: Fri, 28 Dec 2018 14:34:44 -0300
Message-ID: <201812281734.zwh3cexl4p2i@alvherre.pgsql> (raw)
In-Reply-To: <30574.1546015645@sss.pgh.pa.us>
On 2018-Dec-28, Tom Lane wrote:
> I wrote:
> > Alvaro Herrera <alvherre@2ndquadrant.com> writes:
> >> I looked at
> >> https://github.com/postgrespro/pg_wait_sampling/blob/master/pg_wait_sampling.c
> >> https://github.com/citusdata/citus/search?q=pgproc&unscoped_q=pgproc
> >> and skimmed a few others can't find any instance where the full struct
> >> is used, as opposed to just a pointer to it.
>
> > No, the point Michael is making is that the array stride in the ProcArray
> > is part of our ABI. For example, accessing a PGPROC from its pgprocno
> > using the GetPGProcByNumber macro will be broken if we change the
> > struct size. I do not think you can assume that no extension does that.
>
> In fact, there's a counterexample right here in pg_wait_sampling:
>
> https://github.com/postgrespro/pg_wait_sampling/blob/master/pg_wait_sampling.c#L343
Ughh. I stand corrected.
This seems a terrible interface, from an ABI compatibility point of
view, and exposing proclist_node_get() as an inline function, doubly so.
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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To: pgsql-hackers@postgresql.org
Cc: alvherre@2ndquadrant.com, tgl@sss.pgh.pa.us, michael@paquier.xyz, tsunakawa.takay@jp.fujitsu.com, robertmhaas@gmail.com, pgsql-hackers@lists.postgresql.org
Subject: Re: removal of dangling temp tables
In-Reply-To: <201812281734.zwh3cexl4p2i@alvherre.pgsql>
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