Обсуждение: WIP patch for basic window frame support

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
    RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
    RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING
    ROWS UNBOUNDED PRECEDING    -- same as AND CURRENT ROW
    ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
    ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING

            regards, tom lane

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

2009/1/5 Tom Lane <tgl@sss.pgh.pa.us>:
> "Hitoshi Harada" <umi.tanuki@gmail.com> writes:
>> 2008/12/31 Tom Lane <tgl@sss.pgh.pa.us>:
>>> RANGE UNBOUNDED PRECEDING       -- same as AND CURRENT ROW
>>> ROWS UNBOUNDED PRECEDING        -- same as AND CURRENT ROW
>
>> Is this true?
>
> 7.11 syntax rule 9 says so.  AFAICS general rule 5b doesn't discuss the
> case where <window frame bound 2> isn't present, and doesn't need to
> because of syntax rule 9.
>

OK, I've just found it and confirmed Oracle does so.



-- 
Hitoshi Harada

"Hitoshi Harada" <umi.tanuki@gmail.com> writes:
> 2008/12/31 Tom Lane <tgl@sss.pgh.pa.us>:
>> RANGE UNBOUNDED PRECEDING       -- same as AND CURRENT ROW
>> ROWS UNBOUNDED PRECEDING        -- same as AND CURRENT ROW

> Is this true?

7.11 syntax rule 9 says so.  AFAICS general rule 5b doesn't discuss the
case where <window frame bound 2> isn't present, and doesn't need to
because of syntax rule 9.
        regards, tom lane