| From: | Hiroshi Inoue <Inoue(at)tpf(dot)co(dot)jp> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Mike Mascari <mascarm(at)mascari(dot)com>, Martijn van Oosterhout <kleptog(at)svana(dot)org>, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Partial Indices vs. mixing columns and functions |
| Date: | 2001-07-17 01:52:36 |
| Message-ID: | 3B539A64.6FF9106@tpf.co.jp |
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| Thread: | |
| Lists: | pgsql-general |
Tom Lane wrote:
>
> Hiroshi Inoue <Inoue(at)tpf(dot)co(dot)jp> writes:
> > What kind of expression is allowed as the predicate now ?
>
> Anything that doesn't involve an aggregate or a subselect.
>
> (But what the planner can recognize as matching a query's
> WHERE clause is currently much more restricted, just ANDs
> and ORs of simple VAR OP CONST clauses. This could be
> improved in the future.)
>
> > Both the functions used in functional indexes and the
> > predicates used in partial indexes must be deterministic.
> > Are users responsible for it ?
>
> Yes. I don't see how the system could enforce that, without
> prohibiting lots of useful cases.
>
Shouldn't the functions be *cacheable* at least ?
regards,
Hiroshi Inoue
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