Hi Csaba,
Because I have a where clause limiting which records I'm deleting.
I'm deleting old info from a database, so I'm doing:
DELETE FROM sessions WHERE EXISTS (SELECT sessiontime FROM sessions WHERE sessiontime < (timenow-7days) LIMIT 100)
(timenow-7days is evaluated in PHP and made an int).
So every time the page gets hit, I'm deleting up to 100 records that are older than 7 days..
Csaba Nagy wrote:
Hi Chris,
Just a thought: if you have to clear the table anyway, wouldn't it work for you to use truncate ? That should be faster than delete.
HTH, Csaba.
On Thu, 2005-04-07 at 04:11, Chris Smith wrote:
I don't care about the order in my particular case, just that I have to clear the table.
I'll try the subquery and see how I go :)
Thanks!
Neil Conway wrote:
Chris Smith wrote:
I'm trying to use a limit clause with delete, but it doesn't work at the moment
It isn't in the SQL standard, and it would have undefined behavior: the sort order of a result set without ORDER BY is unspecified, so you would have no way to predict which rows DELETE would remove.
delete from table where x='1' limit 1000;
You could use a subquery to achieve this:
DELETE FROM table WHERE x IN (SELECT x FROM table ... ORDER BY ... LIMIT ...);
-Neil
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