Re: AS OF queries

On Wed, Dec 20, 2017 at 5:17 PM, Peter Eisentraut <
peter(dot)eisentraut(at)2ndquadrant(dot)com> wrote:

> On 12/20/17 10:29, Tom Lane wrote:
> > Please say that's just an Oracle-ism and not SQL standard, because it's
> > formally ambiguous. This is required to work by spec:
> >
> > regression=# select x as of from (values(1)) t(x);
> > of
> > ----
> > 1
> > (1 row)
> >
> > so it's not possible for us ever to support an expression that includes
> > top-level "AS OF" (or, pretty much, "AS anything") without some rather
> > enormous pushups.
>
> The SQL standard syntax appears to be something like
>
> "tablename" [ AS OF SYSTEM TIME 'something' ] [ [ AS ] "alias" ]
>
> That's not going to be fun to parse.
>

There was a presentation about this given at FOSDEM PGDay a couple of years
back. Slides at
https://wiki.postgresql.org/images/6/64/Fosdem20150130PostgresqlTemporal.pdf
.

--
Magnus Hagander
Me: https://www.hagander.net/ <http://www.hagander.net/>
Work: https://www.redpill-linpro.com/ <http://www.redpill-linpro.com/>