--On 24. Januar 2010 08:37:13 -0500 Robert Haas <robertmhaas@gmail.com>
wrote:
>>
>> I agree - the requirements here are much looser than for, say, SELECT
>> or UPDATE. But it still has to not suck.
>>
Yeah, i think the meaning of "suck" can be much weakier than for a DML
command. However, if it would degrade the performance of a formerly well
running command in a way, that it would be unusable, that would be annoying.
>> I think the problem case here might be something like this... create
>> ten tables A1 through A10. Now create 10 more tables B1 through B10
>> each of which inherits from all of A1 through A10. Now create 10 more
>> tables C1 through C10 that inherit from B1 through B10. Now create
>> 1000 tables D1 through D1000 that inherit from C1 through C10. Now
>> drop a column from A1.
>
> Er... rename a column from A1, not drop.
>
Did that with a crude pl/pgsql script, and got the following numbers:
Current -HEAD:
Phenom-II 2.6 GHz: Time: 282,471 ms
MacBook: Time: 499,866 ms
With KaiGais recent patch (which covers the TYPE case, too):
Phenom-II 2.6 GHz: Time: 476,800 ms
MacBook: Time: 753,161 ms
--
Thanks
Bernd
