Horton

Re: Can we get rid of repeated queries from pg_dump?

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: depesz@depesz.com
Cc: pgsql-general <pgsql-general@lists.postgresql.org>
Date: 2021-08-26T14:20:29Z
Lists: pgsql-hackers, pgsql-general 
hubert depesz lubaczewski <depesz@depesz.com> writes:
> On Thu, Aug 26, 2021 at 10:02:07AM -0400, Tom Lane wrote:
>> hubert depesz lubaczewski <depesz@depesz.com> writes:
>>> Wouldn't it be possible to get all type formats at once, and cache them
>>> in pg_dump? Or at the very least reuse already received information?

>> Send a patch ...

> Yeah, that's not going to work, my C skills are next-to-none :(
> I guess I'll have to wait till someone else will assume it's a problem,
> someone with skills to do something about it.

Well, you could move it forward by doing the legwork to identify which
queries are worth merging.  Is it really sane to do a global "select
format_type() from pg_type" query and save all the results on the client
side?  I wonder whether there are cases where that'd be a net loss.
You could do the experimentation to figure that out without necessarily
having the C skills to make pg_dump actually do it.

			regards, tom lane

Commits

  1. In pg_dump, avoid doing per-table queries for RLS policies.

  2. Cache the results of format_type() queries in pg_dump.