From: | pasman pasmański <pasman(dot)p(at)gmail(dot)com> |
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To: | pgsql-general <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: New feature: accumulative functions. |
Date: | 2011-09-25 19:20:42 |
Message-ID: | CAOWY8=b1iZFSMM1nqWcrCV-KUZOn7jHzu-qkpRDa=FG9LXz5Qg@mail.gmail.com |
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Lists: | pgsql-general |
I think, it should be new node in executor. Planner select classic
index scan or new functional index scan.
2011/9/25, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
> =?ISO-8859-2?Q?pasman_pasma=F1ski?= <pasman(dot)p(at)gmail(dot)com> writes:
>> My english is not perfect, by accumulative i think about monotonically
>> increasing function.
>
> Oh, I see how that would work. I can't get real excited about it
> though. The use-case seems a bit narrow, and the amount of complexity
> added to the btree search mechanism (thereby slowing down all btree
> searches) would be significant. Furthermore, unless f() is pretty cheap
> to evaluate, you'd end up preferring an index on f(x) anyway, because
> that can be searched without any new evaluations of f().
>
> regards, tom lane
>
--
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pasman
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