Re: So what's an "empty" array anyway?

"Merlin Moncure"  writes:
> ISTM this is the way it should work from SQL level:

> '{}'::int[] empty 1d
> '{{},{}}'::int[] :: empty 2d

The first one looks okay, but ISTM the second one is not describing
an "empty" array: the upper dimension is of length 2.  In particular
I think that under your proposal array_dims() would probably yield
these results:
[1:0][1:2][1:0]

and all of these would be different:

'{{}}'::int[]			[1:1][1:0]
'{{},{}}'::int[]		[1:2][1:0]
'{{},{},{}}'::int[]		[1:3][1:0]

Maybe this is okay but it feels a bit weird.

> If you dump zero dimension arrays, then the problem about what to do
> with array_dims goes away.

I'm not against dropping zero-dimension arrays ...
		regards, tom lane