Re: match_special_index_operator don't work in 7.2.1

On Sun, 19 May 2002, Stephan Szabo wrote:

>
> On Sun, 19 May 2002, Andriy I Pilipenko wrote:
>
> > Please enter a FULL description of your problem:
> > ------------------------------------------------
> >
> > I've upgraded from 7.0.3 to 7.2.1 and noticed that queries like
> >
> > SELECT ... WHERE field LIKE 'something%'
> >
> > take too much time to execute now.
>
> Are you sure that you're running in C locale? If you're unsure,
> you can build pg_controldata in contrib and check.

Thanks for the point - I missed that. I'm running KOI8 locale now and used
C locale in old database.

> (From comments in recent sources:
> /*
> * We want test whether the database's LC_COLLATE setting is safe for
> * LIKE/regexp index optimization.
> *
> * The key requirement here is that given a prefix string, say "foo",
> * we must be able to generate another string "fop" that is greater
> * than all strings "foobar" starting with "foo". Unfortunately, a
> * non-C locale may have arbitrary collation rules in which "fop" >
> * "foo" is not sufficient to ensure "fop" > "foobar". Until we can
> * come up with a more bulletproof way of generating the upper-bound
> * string, the optimization is disabled in all non-C locales.
> *
> * (In theory, locales other than C may be LIKE-safe so this function
> * could be different from lc_collate_is_c(), but in a different
> * theory, non-C locales are completely unpredicable so it's unlikely
> * to happen.)
> */
> )

Kind regards,
Andriy I Pilipenko
PAI1-RIPE