Re: string_to_array with an empty input string

On Wed, Aug 11, 2010 at 4:21 PM, Peter Geoghegan
<peter(dot)geoghegan86(at)gmail(dot)com> wrote:
> On 11 August 2010 18:53, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>>> I think that there's a need for additional built-in array functions,
>>> including one to succinctly test if an array has no elements.
>>
>> What do you propose?  I think the easiest ways to do it right now are:
>>
>> array_length(arr, 1) is null
>>
>> or just using an equality test, like this:
>>
>> arr = '{}'::int[]
>
> What's wrong with something like array_is_empty(anyarray) returns
> boolean? I don't know why we're so apparently averse to creating
> built-in convenience functions. It's quite easy to forget the intent
> of either of those two statements.

Nothing's wrong with it, but the second one seems pretty hard to
forget the intent of... at least to me.

>>> Iterating through an array with plpgsql, for example, is more clunky
>>> than it should be.
>>
>> Really?
>>
>> FOR var IN SELECT UNNEST(arr) LOOP ... END LOOP
>>
>> I mean, doing everything is sort of clunky in PL/pgsql, but this
>> doesn't seem particularly bad as PL/pgsql idioms go.
>
> Right. I agree that many of the idioms are on the clunky side, but I
> think that the fact that my original remarks about iterating over
> arrays generated discussion is a bit telling. unnest() was only
> introduced in PG 8.4.

True... but now we have it.

> Iterating over an array is a simple thing. We should make simple things easy.

I definitely agree that PL/pgsql could be more usable. Or if not,
then some other PL with a better overall design could be more usable.
I am not entirely sure how to create such a thing, however.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise Postgres Company