Good Optimization

There is a simple way to optimize SQL queries involving joins to
PostgreSQL that I think should be handled by Postgre? If one is joining
a tables a,b on attribute "x" and if one has something like x=3 then it
helps A LOT to say: a.x=3 and b.x=3 in addition to saying a.x=b.x ...
The example below shoulds the radical speed gain of doing this, and I
think it isn't something real obvious to most people...

Of course it could just be a common thing to do in SQL, anyway, just
thought I'd let you all know what I discovered.

Here is an example:

ftc=> explain select * from po,tickets where po_id=material_po and
po_id=8888 ;
NOTICE: QUERY PLAN:

Nested Loop (cost=401.34 size=6146 width=158)
-> Index Scan using ipo_po_id_units on po (cost=2.05 size=2
width=94)
-> Index Scan using itickets_mpou on tickets (cost=199.64 size=70650
width=6
4)

EXPLAIN
ftc=>

ftc=> explain select * from po,tickets where po_id=material_po and
po_id=8888 an
d material_po=8888;
NOTICE: QUERY PLAN:

Nested Loop (cost=21.42 size=268 width=158)
-> Index Scan using ipo_po_id_units on po (cost=2.05 size=2
width=94)
-> Index Scan using itickets_material_po on tickets (cost=9.68
size=3073 wid
th=64)

EXPLAIN
ftc=>