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: Robert Haas <robertmhaas(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Postgres hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Daniel Gustafsson <daniel(at)yesql(dot)se>
Subject: Re: Switch to multi-inserts for pg_depend
Date: 2020-08-14 18:23:16
Message-ID: 20200814182316.GA26549@alvherre.pgsql
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On 2020-Aug-14, Michael Paquier wrote:

> Regarding the maximum number of slots allocated. Do people like the
> current approach taken by the patch to do a single loop of the
> dependency entries at the cost of more allocating perhaps too much for
> the array holding the set of TupleTableSlots (the actual slot
> initialization happens only if necessary)? Or would it be preferred
> to scan twice the set of dependencies, discarding pinned dependencies
> in a first scan to build the list of dependencies that would be
> inserted? This way, you can know the exact amount memory to allocated
> for TupleTableSlots, though that's just 64B for each one of them.

It seems a bit silly to worry about allocating just the exact amount
needed; the current approach looked fine to me. The logic to keep track
number of used slots used is baroque, though -- that could use a lot of

Álvaro Herrera
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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