Re: Switch to multi-inserts for pg_depend

From: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
To: Michael Paquier <michael(at)paquier(dot)xyz>
Cc: Daniel Gustafsson <daniel(at)yesql(dot)se>, Robert Haas <robertmhaas(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Postgres hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Switch to multi-inserts for pg_depend
Date: 2020-09-03 14:50:49
Message-ID: 20200903145049.GA14188@alvherre.pgsql
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I agree, this version looks much better, thanks. Two very minor things:

On 2020-Sep-03, Michael Paquier wrote:

> @@ -76,11 +77,23 @@ recordMultipleDependencies(const ObjectAddress *depender,
>
> dependDesc = table_open(DependRelationId, RowExclusiveLock);
>
> + /*
> + * Allocate the slots to use, but delay initialization until we know that
> + * they will be used. The slot initialization is the costly part, and the
> + * exact number of dependencies inserted cannot be known in advance as it
> + * depends on what is pinned by the system.
> + */

I'm not sure you need the second sentence in this comment; keeping the
"delay initialization until ..." part seems sufficient. If you really
want to highlight that initialization is costly, maybe just say "delay
costly initialization".

> + /*
> + * Record the Dependency. Note we don't bother to check for duplicate
> + * dependencies; there's no harm in them.
> + */

No need to uppercase "dependency". (I know this is carried forward from
prior comment, but it was equally unnecessary there.)

> /*
> * Allocate the slots to use, but delay initialization until we know that
> - * they will be used.
> + * they will be used. A full scan of pg_shdepend is done to find all the
> + * dependencies from the template database to copy. Their number is not
> + * known in advance and the slot initialization is the costly part.
> */

As above, this change is not needed.

--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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