Maxim Boguk <maxim(dot)boguk(at)gmail(dot)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