Re: About "Our CLUSTER implementation is pessimal" patch - Mailing list pgsql-hackers

From Heikki Linnakangas
Subject Re: About "Our CLUSTER implementation is pessimal" patch
Date
Msg-id 4B5F3AEC.3060306@enterprisedb.com
Whole thread Raw
In response to Re: About "Our CLUSTER implementation is pessimal" patch  (Leonardo F <m_lists@yahoo.it>)
Responses Re: About "Our CLUSTER implementation is pessimal" patch  (Leonardo F <m_lists@yahoo.it>)
List pgsql-hackers
Leonardo F wrote:
> why is IndexInfo.ii_Expressions a list? How can an index have more than
> one expression? Sorry if it's a stupid question, but I'm not familiar with
> index expressions.

Consider multi-column indexes, ie:

CREATE INDEX i_foo ON foo (length(a), length(b));

Maybe you're confusing expression indexes with partial indexes? The
predicate for a partial index is stored in ii_Predicate, not
ii_Expressions. Although ii_Predicate is a list too; in that case it's a
list of clauses that are implicitly ANDed together.

--  Heikki Linnakangas EnterpriseDB   http://www.enterprisedb.com


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