Re: patch: array_ndims - Mailing list pgsql-hackers

Hello

we talked about these features, but these functionality is solved with
UNNEST operator
http://farrago.sourceforge.net/design/CollectionTypes.html - so if you
like this functionality (I believe, so want it), please implement
UNNEST operator.

Regards
Pavel Stehule

http://www.ibm.com/developerworks/db2/library/techarticle/dm-0710arocena/index.html


2008/10/11 Robert Haas <robertmhaas@gmail.com>:
> After reading Josh Berkus's email suggesting that the intagg module be
> dropped, I was wondering what would be required to create a array
> enumerator (variously called unnest, unroll, array_enum, and, as
> contemplated by the TODO list, array_to_set).  Pavel Stehule's
> generate_subscripts function provides most of what is needed -
> however, you need to know the number of dimensions in the array, and
> it appears we don't have a function to provide that information, at
> least not in a straightforward fashion.  That seems like a pretty
> useful thing to have anyway, so here's a patch to add it.
>
> If you apply it, you can then used the attached PL/pgsql
> implementation of array_to_set().  I am sure that it would be better
> and more efficient to implement this directly in C, but as no one has
> gotten around to that yet this might be kind of handy.  It might even
> be worth adding to the docs, though I'm not sure exactly where.
>
> rhaas=# SELECT * FROM array_to_set(ARRAY[1,2,3,4]);
>  array_to_set
> --------------
>            1
>            2
>            3
>            4
> (4 rows)
>
> rhaas=# SELECT * FROM array_to_set(ARRAY[[1,2,3,4]]);
>  array_to_set
> --------------
>            1
>            2
>            3
>            4
> (4 rows)
>
> rhaas=# SELECT * FROM array_to_set(ARRAY[[[1,2,3,4]]]);
>  array_to_set
> --------------
>            1
>            2
>            3
>            4
> (4 rows)
>
> rhaas=# SELECT * FROM array_to_set(ARRAY[[[[1,2,3,4]]]]);
>  array_to_set
> --------------
>            1
>            2
>            3
>            4
> (4 rows)
>
> rhaas=# SELECT * FROM array_to_set(ARRAY[[[[[1,2,3,4]]]]]);
>  array_to_set
> --------------
>            1
>            2
>            3
>            4
> (4 rows)
>
> rhaas=# SELECT * FROM array_to_set(ARRAY[[[[[[1,2,3,4]]]]]]);
>  array_to_set
> --------------
>            1
>            2
>            3
>            4
> (4 rows)
>
> ...Robert
>
>
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