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

Bernd Helmle <mailings@oopsware.de>

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From: Bernd Helmle <mailings@oopsware.de>
To: Bernd Helmle <mailings@oopsware.de>, Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robert Haas <robertmhaas@gmail.com>, KaiGai Kohei <kaigai@kaigai.gr.jp>, KaiGai Kohei <kaigai@ak.jp.nec.com>, pgsql-hackers@postgresql.org, Thom Brown <thombrown@gmail.com>, Alvaro Herrera <alvherre@commandprompt.com>
Date: 2010-01-24T19:01:10Z
Lists: pgsql-hackers 

--On 24. Januar 2010 19:45:33 +0100 Bernd Helmle <mailings@oopsware.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


-- 
Thanks

	Bernd