Simple Optimization Problem

I need to run a report using some parameters that are optional, I'm
doing this by labeling "0" as the optional value. IE here is a
simplified example:

CREATE TABLE po (po_id int4 PRIMARY KEY, data text);
(insert a bunch of rows)

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

Index Scan using ipo_poid_units on po (cost=2.05 size=1 width=94)

EXPLAIN

ftc=> explain select * from po where (po_id=8888 or 0=8888);
NOTICE: QUERY PLAN:

Seq Scan on po (cost=449.96 size=1751 width=94)

EXPLAIN

I was hoping PostgreSQL could optimize out the boolean condition
given in the where clause, but it causes it to disregard the index
instead of throwing out 0=8888 in the first stage.

This is the only way I can think to do this, I have crystal reports
send through the SQL instead of doing the whole thing itself(Which
involves returning all possible rows... Sigh)... This query is taking 20
minutes as a result... Is there any hope in 6.5 of the optimizer
handling this better?

David Secret
MIS Director
Kearney Development Co., Inc.