Re: Automatic optimization of IN clauses via INNER JOIN

On Thu, Dec 17, 2009 at 10:23 AM, Thomas Hamilton
<thomashamilton76@yahoo.com> wrote:
> Apparently the latest version of MySQL has solved this problem:
http://www.xaprb.com/blog/2006/06/28/why-large-in-clauses-are-problematic/
>
> But I am running PostgreSQL v8.3 and am observing generally that SELECT ... WHERE ... IN (a, b, c, ...) is much
slowerthan SELECT ... INNER JOIN (SELECT a UNION ALL SELECT b UNION ALL SELECT c ...) 

That's certainly not MY observation.  It would be interesting to see
what's going on in your case but you'll need to provide more details.

http://wiki.postgresql.org/wiki/Guide_to_reporting_problems

...Robert