Re: AS OF queries

On 21 December 2017 at 00:17, 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.

Well, the SQL committe seem to specialise in parser torture.

Window functions, anybody?

--
Craig Ringer http://www.2ndQuadrant.com/
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