Re: [HACKERS] generated columns

ne 13. 1. 2019 v 10:43 odesílatel Peter Eisentraut <
peter.eisentraut@2ndquadrant.com> napsal:

> On 11/01/2019 16:22, Pavel Stehule wrote:
> > The documentation contains paragraph
> >
> > +      The generation expression can only use immutable functions and
> cannot
> > +      use subqueries or reference anything other than the current row
> > in any
> > +      way.
> >
> > It is necessary for stored columns?
>
> See here:
>
> https://www.postgresql.org/message-id/b5c27634-1d44-feba-7494-ce5a31f914ca@2ndquadrant.com


I understand - it is logical. But it is sad, so this feature is not
complete. The benefit is not too big - against functional indexes or views.
But it can be first step.


>
> > I tested it with pseudo constant - current_timestamp, session_user. But
> > current_database() is disallowed.
> >
> > on second hand, this is strange
> >
> > postgres=# create table foo3 (inserted text generated always as
> > (current_timestamp) virtual);
> > CREATE TABLE
>
> Ah, the volatility checking needs some improvements.  I'll address that
> in the next patch version.
>

ok


> --
> Peter Eisentraut              http://www.2ndQuadrant.com/
> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
>