Thread: BUG #2913: Subscript on multidimensional array yields no value
The following bug has been logged online: Bug reference: 2913 Logged by: Roman Nowak Email address: roman_nowak@poczta.onet.pl PostgreSQL version: 8.2.1 Operating system: Windows XP Description: Subscript on multidimensional array yields no value Details: SELECT (ARRAY[[1,2],[3,4]])[1]; does not return [1,2] (testes in psql and pgAdmin III): show info that one row was returned but does not display its value following statment works OK btw SELECT (ARRAY[[1,2],[3,4]])[1:1];
I can confirm this is a bug. Added to the TODO list:
o ARRAY[[1,2],[3,4]])[1] should return the same values as
ARRAY[[1,2],[3,4]])[1:1];
---------------------------------------------------------------------------
Roman Nowak wrote:
>
> The following bug has been logged online:
>
> Bug reference: 2913
> Logged by: Roman Nowak
> Email address: roman_nowak@poczta.onet.pl
> PostgreSQL version: 8.2.1
> Operating system: Windows XP
> Description: Subscript on multidimensional array yields no value
> Details:
>
> SELECT (ARRAY[[1,2],[3,4]])[1];
>
> does not return [1,2]
> (testes in psql and pgAdmin III): show info that one row was returned but
> does not display its value
>
> following statment works OK btw
> SELECT (ARRAY[[1,2],[3,4]])[1:1];
>
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--
Bruce Momjian bruce@momjian.us
EnterpriseDB http://www.enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
Bruce Momjian <bruce@momjian.us> writes:
> I can confirm this is a bug. Added to the TODO list:
> o ARRAY[[1,2],[3,4]])[1] should return the same values as
> ARRAY[[1,2],[3,4]])[1:1];
This is not a bug, this is a definitional disagreement, and your TODO
entry presupposes an answer that I don't particularly agree with.
regards, tom lane
Tom Lane wrote:
> Bruce Momjian <bruce@momjian.us> writes:
> > I can confirm this is a bug. Added to the TODO list:
> > o ARRAY[[1,2],[3,4]])[1] should return the same values as
> > ARRAY[[1,2],[3,4]])[1:1];
>
> 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
What is the issue here that makes that not true?
--
Bruce Momjian bruce@momjian.us
EnterpriseDB http://www.enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
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
Tom Lane wrote: > Bruce Momjian <bruce@momjian.us> writes: > > I can confirm this is a bug. Added to the TODO list: > > o ARRAY[[1,2],[3,4]])[1] should return the same values as > > ARRAY[[1,2],[3,4]])[1:1]; > > This is not a bug, this is a definitional disagreement, and your TODO > entry presupposes an answer that I don't particularly agree with. TODO item removed, now that I understand the array behavior. -- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB http://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. +