Обсуждение: Declaring multidimensional arrays in pl/pgsql

Hi, all.

I was wondering, can I really declare a 2-dimensional array of arbitrary
size in pl/pgsql?
According to the docs it seems that only way would be to declare it as
something like :
myArray := ARRAY[[1,2], [3,4], [5,6]];

But what if I pass the dimensions as function parameters?

My postgresql version is 8.1.

Thanks.

On Nov 29, 2007 3:34 AM, Max Zorloff <zorloff@gmail.com> wrote:
> According to the docs it seems that only way would be to declare it as
> something like :
> myArray := ARRAY[[1,2], [3,4], [5,6]];

You can declare arbitrary-sized, n-dimensional arrays:
...
DECLARE
  myArray integer[][]; -- two-dimensional integer array
BEGIN
...
END;
...

See:
http://www.postgresql.org/docs/8.1/static/arrays.html

I wrote:
> You can declare arbitrary-sized, n-dimensional arrays:

Sorry, I re-read your post.

You want to programatically define the array dimensions depending on
function arguments.

You could try building a string, then casting to the correct array
type (not tested).

On Thu, 29 Nov 2007 18:11:22 +0400, Rodrigo De León <rdeleonp@gmail.com>
wrote:

> On Nov 29, 2007 3:34 AM, Max Zorloff <zorloff@gmail.com> wrote:
>> According to the docs it seems that only way would be to declare it as
>> something like :
>> myArray := ARRAY[[1,2], [3,4], [5,6]];
>
> You can declare arbitrary-sized, n-dimensional arrays:
> ...
> DECLARE
>   myArray integer[][]; -- two-dimensional integer array
> BEGIN
> ...
> END;
> ...
>
> See:
> http://www.postgresql.org/docs/8.1/static/arrays.html

I can. But unfortunately :

create or replace function testfunc()
returns setof record as $$
DECLARE
   myArray int[][];
BEGIN
   FOR i IN 1..10 LOOP
     FOR j IN 1..10 LOOP
       RAISE NOTICE '% %', i, j;
       myArray[i][j] := 1;

     END LOOP;
   END LOOP;

   RETURN;
END
$$ language plpgsql;


ponline=# select testfunc();
NOTICE:  1 1
NOTICE:  1 2
ERROR:  invalid array subscripts
КОНТЕКСТ:  PL/pgSQL function "testfunc" line 7 at assignment

2-dimensional arrays do not grow like 1-dimensional do (it says so in the
docs).
The initial array is 1x1 size. I suppose I'm stuck with emulating 2-dim
arrays through
1-dim arrays because I also need them to grow later.

On Thu, 29 Nov 2007 19:21:03 +0400, Pavel Stehule
<pavel.stehule@gmail.com> wrote:

> Hello
>
> arrays in PostgreSQL have to be regular allways. And before 8.3 array
> cannot contais NULL, so you cannot simpl resize two dim array :(. But
> your functions doesn't work in 8.3. too. So you can
>
> a) use 1D array and access to array like myarray[10*(n1-1)+n2]
>
> b) init array with string like
>
> create or replace function testfunc()
> returns void as $$
> DECLARE
>   myArray int[][];
> BEGIN
>   myArray :=  ('{'||array_to_string(array(select
> '{0,0,0,0,0,0,0,0,0,0}'::text from
> generate_series(1,10)),',')||'}')::int[][];
>   FOR i IN 1..10 LOOP
>     FOR j IN 1..10 LOOP
>       RAISE NOTICE '% %', i, j;
>       myArray[i][j] := 1;
>     END LOOP;
>   END LOOP;
>   RETURN;
> END
> $$ language plpgsql;

Thanks for the info, but running the above gives me that :

ponline=# select testfunc();
ERROR:  cannot cast type text to integer[]
CONTEXT:  SQL statement "SELECT  ('{'||array_to_string(array(select
'{0,0,0,0,0,0,0,0,0,0}'::text from
generate_series(1,10)),',')||'}')::int[][]"
PL/pgSQL function "testfunc" line 4 at assignment

I think 8.1 does not have text -> int[] cast available. I think I'm stuck
with option a.

On Thu, 29 Nov 2007 21:15:50 +0400, Rodrigo De León <rdeleonp@gmail.com>
wrote:

> On Nov 29, 2007 9:33 AM, Max Zorloff <zorloff@gmail.com> wrote:
>> I don't think that works.
>>
>> ponline=# select ('{1,2,3}'::text)::int[];
>> ERROR:  cannot cast type text to integer[]
>
> Can you try:
>
> select ('{1,2,3}'::unknown)::int[];

Thanks, that works fine with 2-dim arrays too.