Re: Determining if an hstore is empty

On Mon, Feb 11, 2013 at 11:36 AM, Wells Oliver <wellsoliver(at)gmail(dot)com> wrote:
> What's the canonical way of doing this? Various failed attempts include:

Just compare an empty hstore with yours.

[local]:5432 grayhemp(at)grayhemp=# select ''::hstore = ''::hstore,
''::hstore = '{a=>1}'::hstore;
?column? | ?column?
----------+----------
t | f
(1 row)

>
> select array_length(%%'a=>1'::hstore - 'a=>1'::hstore, 1)
>
> select array_length(%%('a=>1'::hstore - 'a=>1'::hstore), 1)
>
> select array_length(avals('a=>1'::hstore - 'a=>1'::hstore), 1);
>
> select array_length(akeys('a=>1'::hstore - 'a=>1'::hstore), 1);
>
> select skeys('a=>1'::hstore - 'a=>1'::hstore) is null
>
> select 'a=>1'::hstore - 'a=>1'::hstore is null
>
> Etc.
>
> --
> Wells Oliver
> wellsoliver(at)gmail(dot)com

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