Re: pg_dump additional options for performance - Mailing list pgsql-hackers

From Gregory Stark
Subject Re: pg_dump additional options for performance
Date
Msg-id 874pbvfpae.fsf@oxford.xeocode.com
Whole thread Raw
In response to Re: pg_dump additional options for performance  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: pg_dump additional options for performance  (Tom Lane <tgl@sss.pgh.pa.us>)
Re: pg_dump additional options for performance  (Simon Riggs <simon@2ndquadrant.com>)
List pgsql-hackers
"Tom Lane" <tgl@sss.pgh.pa.us> writes:

> Simon Riggs <simon@2ndquadrant.com> writes:
>> I've not been advocating improving pg_restore, which is where the -Fc
>> tricks come in.
>> ...
>> I see you thought I meant pg_restore. I don't thinking extending
>> pg_restore in that way is of sufficiently generic use to make it
>> worthwhile. Extending psql would be worth it, since not all psql scripts
>> come from pg_dump.
>
> OK, the reason I didn't grasp what you are proposing is that it's insane.
>
> We can easily, and backwards-compatibly, improve pg_restore to do
> concurrent restores.  Trying to make psql do something like this will
> require a complete rewrite, and there is no prospect that it will work
> for any input that didn't come from (an updated version of) pg_dump
> anyway.  

I didn't read everything in the thread previously so I'm not sure if this is
what Simon had in mind. But I think one thing that could be done in parallel
even in psql scripts is index builds. That doesn't help speed up COPY but it
does speed up a case where we currently are limited by only occupying a single
cpu. And I would expect it to play well With synchronized scans too.

The "complete rewrite" in this case would be the "concurrent psql" patch I
submitted a while back. I think it's a bit of a mess right now because I was
trying to chase down some bugs with sigint handling so I've been thinking of
rewriting it.

I think this is a low-hanging fruit which would help a lot of users. The
ability to load multiple COPY dumps would be the other piece of the puzzle but
personally I'm not sure how to tackle that.

--  Gregory Stark EnterpriseDB          http://www.enterprisedb.com Ask me about EnterpriseDB's PostGIS support!


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