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

Tatsuo Ishii <ishii@postgresql.org>

From: Tatsuo Ishii <ishii@postgresql.org>

To: tgl@sss.pgh.pa.us

Cc: ojford@gmail.com, vik@postgresfriends.org, pgsql-hackers@postgresql.org, andrew@tao11.riddles.org.uk, david@fetter.org, krasiyan@gmail.com

Date: 2025-01-20T00:18:25Z

Lists: pgsql-hackers

Commits

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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

> Tatsuo Ishii <ishii@postgresql.org> writes:
>>> The latest version restricts it to lag, lead, first_value, last_value,
>>> and nth_value. We can extend it in a subsequent patch if there's
>>> demand?
> 
>> The restriction is required by the SQL standard. So I don't think we
>> need to extend to other window functions.
> 
> The SQL spec does not believe that user-defined window functions are a
> thing.  So its opinion on this point is useless.

Of course the standard does not mention anything about the user
defined window functions and the restriction is not apply to the user
defined window functions.

> I would think that
> IGNORE NULLS is potentially useful for user-defined window functions,
> and we should not be building anything that restricts the feature to
> specific functions.

So you want to allow to use IGNORE NULLS to other built-in window
functions?
--
Tatsuo Ishii
SRA OSS K.K.
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp