Re: AS OF queries

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.

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