Mark, Tim,
> select
> pav1.person_id
> from
> person_attributes_vertical pav1
> where
> ( pav1.attribute_id = 1
> and pav1.value_id in (2,3))
> or ( pav1.attribute_id = 2
> and pav1.value_id in (2,3))
Not the same query, sorry. Daniel's query yields all the person_id's which
have criteria A AND criteria B. Yours gives all the person_id's which have
criteria A OR criteria B.
> There will be a lot of attributes with the same ID; there will also be a
> lot of attributes with the same value. However, there should be much less
> attributes with a specific combination of (ID/Value). Right now I think it
> will be very hard to determine which field has a better selectivity:
> attribute_id or value_id.
Given that there is already an index on ( attribute_id, value_id ) I don't
quite see what difference this makes. Unless you're suggesting this as a
workaround for the PG Planner's poor use of the index?
--
Josh Berkus
Aglio Database Solutions
San Francisco
