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Re: BUG #5784: CREATE INDEX USING GIN complains about array containing null values yet none exist

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Andres Freund <andres(at)anarazel(dot)de>, pgsql-bugs(at)postgresql(dot)org, Martin Atukunda <matlads(at)gmail(dot)com>
Subject: Re: BUG #5784: CREATE INDEX USING GIN complains about array containing null values yet none exist
Date: 2010-12-27 21:14:19
Message-ID: 201012272114.oBRLEJs04232@momjian.us (view raw or flat)
Thread:
Lists: pgsql-bugs
Heikki Linnakangas wrote:
> On 05.12.2010 18:26, Tom Lane wrote:
> > Andres Freund<andres(at)anarazel(dot)de>  writes:
> >> On Sunday 05 December 2010 17:42:59 Tom Lane wrote:
> >>> I think the reason the given example fails is just that it's all being
> >>> done in one transaction.  If the null-containing row were known dead
> >>> it wouldn't get indexed.  So: commit.
> >
> >> Um I doubt it.
> >
> > [ gets out gdb... ]  Oh: the reason GIN is complaining is that it's just
> > looking at ARR_HASNULL(), and the array's has-nulls flag is still set
> > because we don't bother to try to clear it after replacing one element
> > of the array.  (Which in general would be an expensive thing to try to
> > do...)
> >
> > If we were intending to leave GIN in its current nulls-hating state,
> > the thing to do would be to replace the stupid ARR_HASNULL check with
> > something more intelligent.  But really it needs to be fixed to handle
> > nulls properly, so I'm thinking that might be a dead-end patch.
> 
> Sounds like we'd still want to just replace ARR_HASNULL() with something 
> more intelligent in back-branches though.

Added to TODO:

	Improve GIN's handling of NULL array values
	
	    * http://archives.postgresql.org/pgsql-bugs/2010-12/msg00032.php

-- 
  Bruce Momjian  <bruce(at)momjian(dot)us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +

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