Re: WIP patch for basic window frame support - Mailing list pgsql-hackers

2008/12/31 Tom Lane <tgl@sss.pgh.pa.us>:
> No docs or regression tests yet, but it seems to work ... please check
> against Oracle and DB2 behavior.  Supported cases are
>
>        RANGE UNBOUNDED PRECEDING       -- same as AND CURRENT ROW
>        ROWS UNBOUNDED PRECEDING        -- same as AND CURRENT ROW

Is this true?
I guess that the 7.11 rule 5.b in the spec says as far as the bound is
not specified in the window frame clause, all rows of the partition
are contained in the frame. The rule then removes rows from the
initial frame as the frame bound indicates.

So as the result,
RANGE UNBOUNDED PRECEDING
ROWS UNBOUNDED PRECEDING
both mean
(RANGE / ROWS) BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING
if I don't miss something.

Regards,


-- 
Hitoshi Harada