Re: Really really slow select count(*)

On 02/04/2011 02:14 PM, felix wrote:

> oh and there in the footnotes to django they say "dont' forget to run
> the delete expired sessions management every once in a while".
> thanks guys.

Oh Django... :)

> it won't run now because its too big, I can delete them from psql though

You might be better off deleting the inverse. You know, start a
transaction, select all the sessions that *aren't* expired, truncate the
table, insert them back into the session table, and commit.

BEGIN;
CREATE TEMP TABLE foo_1 AS
SELECT * FROM django_session WHERE date_expired < CURRENT_DATE;
TRUNCATE django_session;
INSERT INTO django_session SELECT * from foo_1;
COMMIT;

Except I don't actually know what the expired column is. You can figure
that out pretty quick, I assume. That'll also have the benefit of
cleaning up the indexes and the table all at once. If you just do a
delete, the table won't change at all, except that it'll have less
active records.

> well just think how sprightly my website will run tomorrow once I fix
> these.

Maybe. :)

--
Shaun Thomas
OptionsHouse | 141 W. Jackson Blvd. | Suite 800 | Chicago IL, 60604
312-676-8870
sthomas(at)peak6(dot)com

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