Re: Add RESPECT/IGNORE NULLS and FROM FIRST/LAST options

Tatsuo Ishii <ishii@postgresql.org>

From: Tatsuo Ishii <ishii@postgresql.org>

To: ojford@gmail.com

Cc: tgl@sss.pgh.pa.us, vik@postgresfriends.org, pgsql-hackers@postgresql.org, andrew@tao11.riddles.org.uk, david@fetter.org, krasiyan@gmail.com

Date: 2025-01-22T11:58:18Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Fix coding style with "else".
- 20628b62e46e 19 (unreleased) landed
Fix multi WinGetFuncArgInFrame/Partition calls with IGNORE NULLS.
- 2d7b247cb414 19 (unreleased) landed
Fix Coverity issue reported in commit 2273fa32bce.
- dd766a441d69 19 (unreleased) landed
Use ereport rather than elog in WinCheckAndInitializeNullTreatment.
- 5f3808646f67 19 (unreleased) landed
Avoid uninitialized-variable warnings from older compilers.
- 71540dcdcb22 19 (unreleased) cited
Fix Coverity issues reported in commit 25a30bbd423.
- 2273fa32bce7 19 (unreleased) landed
Improve EXPLAIN's display of window functions.
- 8b1b342544b6 18.0 cited
Automatically generate node support functions
- 964d01ae90c3 16.0 cited

> Attached version moves the setting of IGNORE_NULLS to the window
> function itself, with the functions that don't allow it erroring out.
> This is done with a new api: WinCheckAndInitializeNullTreatment.
> 
> Custom functions that don't call this will simply not have the
> IGNORE_NULLS option set as this api initializes the option and the
> array. As per the previous discussion, it should have correct
> formatting and handle the Exclusion clauses correctly.

I played with the v4 patch. It seems lead() produces incorrect result:

test=# SELECT x,y,lead(y) IGNORE NULLS OVER (ORDER BY x) FROM (VALUES(1,NULL),(2,2),(3,NULL)) AS v(x,y);
 x | y | lead 
---+---+------
 1 |   |    2
 2 | 2 |    2
 3 |   |    2
(3 rows)

I think correct result of "lead" column is 2, NULL, NULL.

Best reagards,
--
Tatsuo Ishii
SRA OSS K.K.
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp