Re: Postgres 8.3, four times slower queries?

On Wed, Mar 4, 2009 at 6:20 PM, Aaron Guyon <battlemage@gmail.com> wrote:
> On Tue, Mar 3, 2009 at 5:34 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>>
>> Comparisons on
>> numerics aren't terribly fast though (in either release).  I wonder
>> whether you could change the key columns to int or bigint.
>
> I changed the affected columns from numeric to integers and I was unable to
> get any performance gain:
> 8.3.3: 1195 ms
> 8.2.12: 611 ms
>
> I've attached the new query plans.
>
>> Are you doing
>> something to force the join order, like running with a small
>> join_collapse_limit setting?  If so maybe you shouldn't.
>
> No, we left the join_collapse_limit to the default 8.  We tried a higher
> value, but there was no difference in performance.
>
> I'll post the query and the table descriptions in separate messages to the
> list to avoid my mail from being rejected for exceeding the size limit :)

Well, it looks like the problem is that 8.3 is not using the index
idx_bundle_content_bundle_id.  But I don't know why that should be
happening, unless there's a problem with that index.

...Robert