Re: Query - CPU issue

On Wed, Sep 18, 2013 at 6:08 AM, Jayadevan M <maymala(dot)jayadevan(at)gmail(dot)com>wrote:

>
> The function doesn't do much, code given below -
> CREATE OR REPLACE FUNCTION geoip_city(IN p_ip bigint, OUT loc_desc
> character varying)
> RETURNS character varying AS
> $BODY$
> SELECT l.id || l.country ||l.region || l.city FROM blocks b JOIN
> locations l ON (b.location_id = l.id)
> WHERE $1 >= start_ip and $1 <= end_ip limit 1 ;
> $BODY$
> LANGUAGE sql IMMUTABLE
> COST 100;
>
> There are indexes on the start_ip and end_ip and an explain tells me the
> indexes are being used (if I execute the SELECT in the function using a
> valid value for the ip value.
>

That construct is not efficiently indexable using two independent btree
indexes. What did the plan look like that used the index? Two large
bitmaps with a bitmap_and?

If you build ranges consisting of [start_ip, end_ip] and then build an
index that specializes in range queries (GiST, I think) it should be able
to do it efficiently, but you would have to rewrite the query to use a
contains operator rather than two independent inequality tests.

Cheers,

Jeff