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Re: Row IS NULL question

From: Gevik Babakhani <pgdev(at)xs4all(dot)nl>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Teodor Sigaev <teodor(at)sigaev(dot)ru>, Pgsql Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Row IS NULL question
Date: 2006-09-28 18:49:59
Message-ID: 1159469399.17359.2.camel@voyager.truesoftware.net (view raw or flat)
Thread:
Lists: pgsql-hackers
Thank you for the explanation.

On Thu, 2006-09-28 at 12:06 -0400, Tom Lane wrote:
> Gevik Babakhani <pgdev(at)xs4all(dot)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
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 2: Don't 'kill -9' the postmaster
> 
-- 
Regards,
Gevik Babakhani
http://www.postgresql.nl
http://www.truesoftware.nl







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