Re: Compund indexes and ORs

Dmitry Tkach writes:

> explain select * from abc where a=1 and b in (1,2);
>
> QUERY PLAN
> ---------------------------------------------------------------------
> Index Scan using abc_idx on abc (cost=0.00..17.09 rows=1 width=12)
> Index Cond: (a = 1)
> Filter: ((b = 1) OR (b = 2))
>
>
> Now, why doesn't it want to use the index for the second condition???

It can only use all columns of a multicolumn index if the columns are used
in clauses connected by OR. This is described in the documentation.

--
Peter Eisentraut peter_e(at)gmx(dot)net