Re: array_agg and array_accum (patch)

Here's an updated patch for just array_accum() with some simple docs. If
I should document this in more places, let me know.

I decided not to include array_agg() in this patch because it doesn't
support the standard's ORDER BY clause.

My reasoning is that, if someone is using the standard array_agg() and
porting to PostgreSQL, there's a fairly high chance they would be using
the ORDER BY clause as well, due to the nature of the function. If not,
and they really want a function called array_agg that returns NULL on no
input, it would be trivial to just create an extra final function that
behaved that way and create a new aggregate.

However, if people want me to put array_agg() back in I will.

Regards,
Jeff Davis