Re: postgres 7.4 vs 8.x redux: query plans

On 4/3/07, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> "Alex Deucher" <alexdeucher@gmail.com> writes:
> > and here are the query plans referenced in my last email (apologies if
> > you get these twice, they didn't seem to go through the first time,
> > perhaps due to size?).  I cut out the longer ones.
>
> The first case looks a whole lot like 8.2 does not think it can use an
> index for LIKE, which suggests strongly that you've used the wrong
> locale in the 8.2 installation (ie, not C).
>
> The second pair of plans may look a lot different but in principle they
> ought to perform pretty similarly.  I think the performance differential
> may at root be that string comparison is way more expensive in the 8.2
> installation, which again is possible if you went from C locale to some
> other locale.
>
> In short: check out "show lc_collate" in both installations.

OK, cool, the old one was C and the new one as not.  So I dumped the
DB and re-inited the DB with the locale set to C, then reloaded the
dump, but I'm still getting the same behavior.  Any ideas?

Thanks,

Alex

>
>                         regards, tom lane
>