| From: | Atri Sharma <atri(dot)jiit(at)gmail(dot)com> |
|---|---|
| To: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
| Cc: | KaiGai Kohei <kaigai(at)ak(dot)jp(dot)nec(dot)com>, David Rowley <dgrowleyml(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Amit Kapila <amit(dot)kapila(at)enterprisedb(dot)com> |
| Subject: | Re: Combining Aggregates |
| Date: | 2014-12-17 10:02:12 |
| Message-ID: | CAOeZVicT7E=_rNSO6=s6kQ_TY0_1-uKENW5Yi56oRg4=R93kaw@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, Dec 17, 2014 at 3:23 PM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>
> KaiGai, David Rowley and myself have all made mention of various ways
> we could optimize aggregates.
>
> Following WIP patch adds an extra function called a "combining
> function", that is intended to allow the user to specify a
> semantically correct way of breaking down an aggregate into multiple
> steps.
>
> Gents, is this what you were thinking? If not...
>
>
>
A quick look at the patch makes me assume that the patch does not handle
the problem of combining transvals or move at all in that direction (which
is fine, just reconfirming).
So, essentially, we are adding a "grand total" on top of individual sum()
or count() operations,right?
Also, should we not have a sanity check for the user function provided?
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