Re: BUG #2913: Subscript on multidimensional array yields no value - Mailing list pgsql-bugs

From Tom Lane
Subject Re: BUG #2913: Subscript on multidimensional array yields no value
Date
Msg-id 14949.1170215057@sss.pgh.pa.us
Whole thread Raw
In response to Re: BUG #2913: Subscript on multidimensional array yields no value  (Bruce Momjian <bruce@momjian.us>)
List pgsql-bugs
Bruce Momjian <bruce@momjian.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

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