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

From: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: 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: 2010-12-06 22:20:46
Message-ID: 4CFD61BE.7060301@enterprisedb.com (view raw or flat)
Thread:
Lists: pgsql-bugs
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.

-- 
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com

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