| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | Petr Jelinek <petr(dot)jelinek(at)2ndquadrant(dot)com> |
| Cc: | Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, Erik Rijkers <er(at)xs4all(dot)nl>, Steve Singer <steve(at)ssinger(dot)info>, Craig Ringer <craig(at)2ndquadrant(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, pgsql-hackers-owner(at)postgresql(dot)org |
| Subject: | Re: Logical Replication WIP |
| Date: | 2016-12-13 21:06:58 |
| Message-ID: | 20161213210658.nc3ectm43slziwtr@alap3.anarazel.de |
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| Lists: | pgsql-hackers |
On 2016-12-13 06:55:31 +0100, Petr Jelinek wrote:
> >> This is a quadratic algorithm - that could bite us... Not sure if we
> >> need to care. If we want to fix it, one approach owuld be to use
> >> RangeVarGetRelid() instead, and then do a qsort/deduplicate before
> >> actually opening the relations.
> >>
> >
> > I guess it could get really slow only with big inheritance tree, I'll
> > look into how much work is the other way of doing things (this is not
> > exactly hot code path).
> >
>
> Actually looking at it, it only processes user input so I don't think
> it's very problematic in terms of performance. You'd have to pass many
> thousands of tables in single DDL to notice.
Well, at least we should put a CHECK_FOR_INTERRUPTS there. At the moment
it's IIRC uninterruptible, which isn't good for something directly
triggered by the user. A comment that it's known to be O(n^2), but
considered acceptable, would be good too.
Andres
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