On Wed, May 23, 2012 at 12:14 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Maxim Boguk <maxim.boguk@gmail.com> writes:
> > if anytextcat() and textanycat() are marked volatile,
> > why the database allows create index on supposedly to be volatile
> > expression:
> > create index test_val_special on test((val || ''));
>
> CREATE INDEX inlines anytextcat (which is just a SQL function) before
> making the volatility test, cf commit 5a86e5e19. The reason the
> subselect flattening code has difficulty with this case is that that
> happens before function inlining does, so the expression still looks
> volatile even though it really isn't.
>
> regards, tom lane
>
Thank you very much for all detailed explanation and all help.
Kind Regards,
Maksym