At 08:21 PM 1/14/02 -0500, Tom Lane wrote:
>jboes@nexcerpt.com (Jeff Boes) writes:
>> My situation: table A has 200,000 rows. I've made up a temporary table
>> which holds the single-valued primary key for 80,000 rows which I want
>> to delete.
>> DELETE FROM a WHERE id IN (select ID from tmp LIMIT 800);
>> runs for several minutes.
>
>WHERE ... IN ... is notoriously inefficient. I'd try
>
> DELETE FROM aa WHERE id = tmp.id;
>
>which is not standard SQL but should be able to produce a decent plan.
Nice alternative. Is there an alternate format for this one:
DELETE FROM teamwork WHERE emp NOT IN ( SELECT DISTINCT emp FROM timesheet WHERE lo_shift >
(now()-'90days'::interval))
Frank
