Re: add more frame types in window functions (ROWS) - Mailing list pgsql-hackers

Andrew Gierth <andrew@tao11.riddles.org.uk> writes:
> (A question here: the spec allows (by my reading) the use of
> parameters in the window frame clause, i.e. BETWEEN $1 PRECEDING AND
> $2 FOLLOWING.  Wouldn't it therefore make more sense to treat the
> values as Exprs, albeit very limited ones, and eval them at startup
> rather than assuming we know the node type and digging down into it
> all over the place?)

Seems like you might as well allow any expression not containing
local Vars.  Compare the handling of LIMIT.
        regards, tom lane