On 24 Apr 2007 14:26:46 -0700, zardozrocks <zardozrocks@gmail.com> wrote:
> I have this table:
>
> CREATE TABLE test_zip_assoc (
> id serial NOT NULL,
> f_id integer DEFAULT 0 NOT NULL,
> lat_radians numeric(6,5) DEFAULT 0.00000 NOT NULL,
> long_radians numeric(6,5) DEFAULT 0.00000 NOT NULL
> );
> CREATE INDEX lat_radians ON test_zip_assoc USING btree (lat_radians);
> CREATE INDEX long_radians ON test_zip_assoc USING btree
> (long_radians);
>
>
>
> It's basically a table that associates some foreign_key (for an event,
> for instance) with a particular location using longitude and
> latitude. I'm basically doing a simple proximity search. I have
> populated the database with *10 million* records. I then test
> performance by picking 50 zip codes at random and finding the records
> within 50 miles with a query like this:
>
> SELECT id
> FROM test_zip_assoc
> WHERE
> lat_radians > 0.69014816041
> AND lat_radians < 0.71538026567
> AND long_radians > -1.35446228028
> AND long_radians < -1.32923017502
>
>
> On my development server (dual proc/dual core Opteron 2.8 Ghz with 4GB
> ram) this query averages 1.5 seconds each time it runs after a brief
> warmup period. In PostGreSQL it averages about 15 seconds.
>
> Both of those times are too slow. I need the query to run in under a
> second with as many as a billion records. I don't know if this is
> possible but I'm really hoping someone can help me restructure my
> indexes (multicolumn?, multiple indexes with a 'where' clause?) so
> that I can get this running as fast as possible.
>
> If I need to consider some non-database data structure in RAM I will
> do that too. Any help or tips would be greatly appreciated. I'm
> willing to go to greath lengths to test this if someone can make a
> good suggestion that sounds like it has a reasonable chance of
> improving the speed of this search. There's an extensive thread on my
> efforts already here:
You can always go the earthdist route. the index takes longer to
build (like 5x) longer than btree, but will optimize that exact
operation.
merlin
