| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Stephen Frost <sfrost(at)snowman(dot)net> |
| Cc: | Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Magnus Hagander <magnus(at)hagander(dot)net> |
| Subject: | Re: Further pg_upgrade analysis for many tables |
| Date: | 2013-01-20 19:32:29 |
| Message-ID: | 27066.1358710349@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Stephen Frost <sfrost(at)snowman(dot)net> writes:
> I'm curious if this is going to help with rollback's of transactions
> which created lots of tables..? We've certainly seen that take much
> longer than we'd like, although I've generally attributed it to doing
> all of the unlink'ing and truncating of files.
If a single transaction creates lots of tables and then rolls back,
this patch won't change anything because we'll long since have
overflowed the eoxact list. But you weren't seeing an O(N^2) penalty
in such cases anyway: that penalty came from doing O(N) work in each
of N transactions. I'm sure you're right that you're mostly looking
at the filesystem cleanup work, which we can't do much about.
regards, tom lane
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