Re: [BUG?] strange behavior in ALTER TABLE ... RENAME TO on inherited columns

(2010/01/25 4:01), Bernd Helmle wrote:
>
>
> --On 24. Januar 2010 19:45:33 +0100 Bernd Helmle <mailings(at)oopsware(dot)de>
> wrote:
>
>> I don't see where this should be related to the number of tables not
>> part of the inheritance tree (or inheritance at all).
>
> To answer that myself: it seems get_attname() introduces the overhead
> here (forgot about that). Creating additional 16384 tables without any
> connection to the inheritance increases the times on my Phenom-II Box to
> round about 2 seconds:
>
>
> Current -HEAD
>
> bernd=# ALTER TABLE a1 RENAME COLUMN acol1 TO xyz;
> ALTER TABLE
> Time: 409,045 ms
>
>
> With KaiGai's recent patch:
>
> bernd=# ALTER TABLE a1 RENAME COLUMN acol1 TO xyz;
> ALTER TABLE
> Time: 2402,306 ms

Hmm....

Bernd, could you try same test with previous patch?
http://archives.postgresql.org/message-id/4B41BB04.2070609@ak.jp.nec.com

It computes an expected inhcount during find_all_inheritors(), and
compares it with the target pg_attribute entry?

I'll also try to measure performance in three cases by myself.
Please wait for a while...

Thanks,
--
OSS Platform Development Division, NEC
KaiGai Kohei <kaigai(at)ak(dot)jp(dot)nec(dot)com>