Re: Avoid huge perfomance loss on string concatenation

> just small correction here...expressions like that in the create index
> need an extra set of parens (but I agree with your sentiment):
> CREATE INDEX dokindex ON dok ((kuupaeve||kellaaeg))

I tried

CREATE INDEX dok_kuupaev_kellaaeg_idx ON dok ((kuupaev||kellaaeg));

but got error

ERROR: functions in index expression must be marked IMMUTABLE
SQL state: 42P17

How to create such index ?

Andrus.