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Re: [Bizgres-general] A Guide to Constraint Exclusion (

Simon Riggs <simon@2ndquadrant.com>

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From: Simon Riggs <simon@2ndquadrant.com>
To: Luke Lonergan <llonergan@greenplum.com>
Cc: bizgres-general <bizgres-general@pgfoundry.org>, pgsql-hackers@postgresql.org
Date: 2005-07-14T22:22:03Z
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