Subselect query enhancement

["Michael Artz" <mlartz@xxxxxxxxx>]

I'm needing help determining the best all-around query for the
following situation.  I have primary table that holds ip information
and two other tables that hold event data for the specific IP in with
a one-to-many mapping between them, ie:

CREATE TABLE ip_info (
   ip IP4,
   --other data
);

CREATE TABLE network_events (
   ip IP4 NOT NULL REFERENCES ip_info(ip),
   name VARCHAR,
   port INTEGER,
   --other data
);

CREATE TABLE host_events (
   ip IP4 NOT NULL REFERENCES ip_info(ip),
   name VARCHAR
   port INTEGER,
   --other data
);

There is quite a bit of commonality between the network_events and
host_events schemas, but they do not currently share an ancestor.
ip_info has about 13 million rows, the network_events table has about
30 million rows, and the host_events table has about 7 million rows.
There are indexes on all the rows.

The query that I would like to execute is to select all the rows of
ip_info that have either  network or host events that meet some
criteria, i.e. name='blah'.  I have 3 different possibilities that I
have thought of to execute this.

First, 2 'ip IN (SELECT ...)' statements joined by an OR:

SELECT * FROM ip_info
 WHERE ip IN (SELECT ip FROM network_events WHERE name='blah')
       OR ip IN (SELECT ip FROM host_events WHERE name='blah');

Next, 1 'ip IN (SELECT ... UNION SELECT ...) statement:

SELECT * FROM ip_info
 WHERE ip IN (SELECT ip FROM network_events WHERE name='blah'
             UNION
             SELECT ip FROM host_events WHERE name='blah');

Or, finally, the UNION statment with DISTINCTs:

SELECT * FROM ip_info
 WHERE ip IN (SELECT DISTINCT ip FROM network_events WHERE name='blah'
             UNION
             SELECT DISTINCT ip FROM host_events WHERE name='blah');