Re: [HACKERS] Array slice subscripts (was Re: plpgsql function

Is this a TODO item?

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Tom Lane wrote:
> Andre Holzner <Andre.Holzner@cern.ch> writes:
> > Am I doing something wrong or is this a 'feature' ? 
> 
> What's biting you is that the array slice operator uses the provided
> lower bounds in the resultant array.  For example:
> 
> regression=# select pcha from zdec_bhab;
>                 pcha
> ------------------------------------
>  {{11,12,13},{21,22,23},{31,32,33}}
> (1 row)
> 
> regression=# select array_dims(pcha) from zdec_bhab;
>  array_dims
> ------------
>  [1:3][1:3]
> (1 row)
> 
> regression=# select pcha[2:2][1:3] from zdec_bhab;
>      pcha
> --------------
>  {{21,22,23}}
> (1 row)
> 
> regression=# select array_dims(pcha[2:2][1:3]) from zdec_bhab;
>  array_dims
> ------------
>  [2:2][1:3]
> (1 row)
> 
> So your function receives an array with first index starting at 2,
> which it's not expecting; its attempt to fetch element [1][1] is out
> of bounds and produces a NULL.
> 
> Offhand this behavior seems like a misfeature: perhaps it'd be more
> sensible for the extracted slice to always have index lower bounds
> set to 1.  But I'd like to see some discussion before changing it
> (and I don't plan to touch it before 7.2 release, in any case ;-)).
> 
> Comments anyone?
> 
>             regards, tom lane
> 
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