Re: BUG #2913: Subscript on multidimensional array yields no value

[Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>]

Bruce Momjian <bruce(at)momjian(dot)us> writes:
> Tom Lane wrote:
>> This is not a bug, this is a definitional disagreement, and your TODO
>> entry presupposes an answer that I don't particularly agree with.

> Well, our documentation suggests thaat [1] is the same as [1:1]:
> 	http://www.postgresql.org/docs/8.2/static/arrays.html#AEN5791

It says absolutely no such thing.  A subscript expression involving m:n
produces a "slice", hence an array of different dimensionality from the
original, whereas a subscript expression not involving any colon
produces a single element --- that is, not an array at all.

You could make a fair case that the (ARRAY[[1,2],[3,4]])[1] example
should throw an error instead of returning null.  But to claim it is
the same as a slice expression is a typing violation.

			regards, tom lane