Spatial query on large table with multiple self joins performing slow

Question

I am working on queries on a large table in Postgres 9.3.9. It is a spatial dataset and it is spatially indexed. Say, I have need to find 3 types of objects: A, B and C. The

Answer 1

Does it make any difference if you use explicit joins?

SELECT a.id as a_id, a.name as a_name, a.geog as a_geog,
       b.id as b_id, b.name as b_name, b.geog as b_geog,
       c.id as c_id, c.name as c_name, c.geog as c_geog
FROM table1 a
JOIN table1 b ON b.type = 'B' AND ST_DWithin(a.geog, b.geog, 100)
JOIN table1 c ON c.type = 'C' AND ST_DWithin(a.geog, c.geog, 100)
WHERE a.type = 'A';