Re: cardinality()

2009/3/1 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
> I wrote:
>> The standard doesn't have multi-dimensional arrays, so it's entirely
>> possible that somewhere in it there is wording that makes cardinality()
>> equivalent to the length of the first dimension.  But I concur with
>> Andrew that this is flat wrong when extended to m-d arrays.
>
> I poked around in the SQL:2008 draft a bit.  AFAICT the most precise
> statement about cardinality() is in 6.27 <numeric value function>:
>
>  <cardinality expression> ::=
>        CARDINALITY<left paren> <collection value expression> <right paren>
>
>  7) The result of <cardinality expression> is the number of elements of
>     the result of the <collection value expression>.
>
> Now the standard is only considering 1-D arrays, but I fail to see any
> way that it could be argued that the appropriate reading of "number of
> elements" for a multi-D array is the length of the first dimension.
> So I think Andrew is right and we need to fix our implementation of
> cardinality() while we still can.

₊1

regards
Pavel Stehule

>
>                        regards, tom lane
>
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