Re: Long-running DELETE...WHERE...

Nice syntax.  Could not find in doc.  Do you have any ideas where I
could find it?

--- Tom Lane <tgl@sss.pgh.pa.us> 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.
> 
> You might find that a VACUUM ANALYZE on both tables beforehand would
> be
> a good idea, too; never-vacuumed temp tables have some default
> statistics assumed that are a lot less than 80k rows.
> 
>             regards, tom lane
> 
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