Re: index theory

On Wed, 2002-10-16 at 09:19, Karel Zak wrote:
> 
>  Hi,
> 
>  I have SQL query:
> 
>  SELECT * FROM ii WHERE i1='a' AND i2='b';
> 
>  There're indexes on i1 and i2. I know best solution is use one
>  index on both (i1, i2).
> 
>  The EXPLAIN command show that optimalizer wants to use one index:
> 
> test=# explain SELECT * FROM ii WHERE i1='a' AND i1='b';
>                                    QUERY PLAN                                    
> ---------------------------------------------------------------------------------
>  Index Scan using i1 on ii  (cost=0.00..4.83 rows=1 width=24)
>    Index Cond: ((i1 = 'a'::character varying) AND (i1 = 'b'::character varying))

I think you typo'd.  i1='a' AND i1='b' turns into 'a' = 'b' which
certainly isn't true in any alphabets I know of.

--  Rod Taylor