Re: Row IS NULL question

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От Tom Lane
Тема Re: Row IS NULL question
Дата
Msg-id 26322.1159459609@sss.pgh.pa.us
обсуждение исходный текст
Ответ на Re: Row IS NULL question  (Gevik Babakhani <pgdev@xs4all.nl>)
Ответы Re: Row IS NULL question  (Gevik Babakhani <pgdev@xs4all.nl>)
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Gevik Babakhani <pgdev@xs4all.nl> writes:
> Does this have anything to do with ExecEvalWholeRowVar?

Yeah, the construct

>> Seq Scan on int8_tbl x  (cost=0.00..1.05 rows=1 width=16)
>> Filter: (x.* IS NULL)

is really ExecEvalNullTest applied to the result of ExecEvalWholeRowVar.

If we simply push makeRowNullTest() to later in the parser, this case
will work as expected, but there is still the issue of IS [NOT] NULL
applied to rowtype values that are not coming from ROW() constructs,
such as the result of a rowtype-returning function.  Likewise, null
tests on arrays really would have to be handled in the executor to
work per spec --- we can hardly break them down into scalar isnull
tests at parse time, which is what makeRowNullTest() is trying to do.
        regards, tom lane


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