Re: About "Our CLUSTER implementation is pessimal" patch

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