Re: PoC: Grouped base relation

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
Cc: "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: PoC: Grouped base relation
Date: 2017-01-20 20:04:58
Message-ID: CA+TgmoYedhCq71yRzC66=tez1p-H=x0U0GQqKL91bwhTx_WRag@mail.gmail.com
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On Thu, Jan 19, 2017 at 2:19 AM, Tomas Vondra
<tomas(dot)vondra(at)2ndquadrant(dot)com> wrote:
>> Not all aggregates have TransValue * integer = newTransValue
>> behaviour. Example is array_agg() or string_agg() has "TransValue
>> concatenated integer time" behaviour. Or an aggregate "multiplying"
>> values across rows will have TransValue (raised to) integer behaviour.
>> Labelling all of those as "multi" doesn't look good.
>
> All aggregates that have (or can have) a combine function have it, because
> in the worst case you can simply implement it by calling the combine
> function repeatedly.

+1.

> Also, if you treat the combine function as "+" then the "multiply" function
> is exactly what "*" is expected to do. So I find the naming quite
> appropriate, actually.

+1.

> But I think naming of the function is not the most important aspect of the
> patch, I believe. In the worst case, we can do s/multi/whatever/ sometime
> later.

Yeah.

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

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