| From: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
|---|---|
| To: | Luke Lonergan <llonergan(at)greenplum(dot)com> |
| Cc: | bizgres-general <bizgres-general(at)pgfoundry(dot)org>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: [Bizgres-general] A Guide to Constraint Exclusion ( |
| Date: | 2005-07-14 22:22:03 |
| Message-ID: | 1121379723.3970.487.camel@localhost.localdomain |
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| Thread: | |
| Lists: | pgsql-hackers |
On Thu, 2005-07-14 at 15:16 -0700, Luke Lonergan wrote:
> Simon,
>
> > SELECT
> > FROM Fact, Dimension
> > WHERE Fact.Key = Dimension.Key
> > AND Dimension.DescriptiveField = 'Blah'
>
> So, what happens with this:
>
> SELECT
> FROM Fact, Dimension
> WHERE Fact.Key = Dimension.Key
> AND Fact.part = 100;
>
> With Fact defined with 3 partitions:
> CHECK(Part BETWEEN 1 AND 1000)
> CHECK(Part BETWEEN 1001 AND 2000)
> CHECK(Part BETWEEN 2001 AND 3000)
>
> Will the 2nd and 3rd partitions be eliminated?
Yes.
That is because the clause "part = 100" is a direct restriction on the
partitioned table, using an immutable operator and a constant.
Best Regards, Simon Riggs
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