Re: ERROR: functions in index expression must be marked IMMUTABLE

On 03.03.2017 11:43, Geoff Winkless wrote:
> One alternative would be to make to_date accept all language variants
> of months simultaneously. A quick search of google suggests that there
> aren't any overlaps between languages (ie where one language uses
> "Foo" for March and another uses "Foo" for May), although you would
> have to​ do some more intense research to be sure. As far as I can see
> there's no other reason why to_date would need to be marked as
> stable/volatile, is there?

I don't think so. It could be viable.

> On the down side I imagine it would involve some
> potentially-prohibitively-large lookup tables; it would also end up
> with a technical incompatibility in that what ANSI SQL would reject as
> not-a-date might be parsed as a date.

There is another issue: languages change (admittedly very slowly) but I
wouldn't want PostgreSQL to be incompatible with future generations.
Your performance argument weighs heavier, though.

> I'm not in a position to judge if either of those would be acceptable.

Do you think I should post to pgsql-hackers?

Sven