Query speed

I'm working on moving several medium size tables from Oracle to Postgres. The
table I'm dealing with has 210000 rows. I've indexed the table with a simple
single column index on a varchar(30) column that is unique but doesn't have a
unique constraint placed on it.

When I issue a select* from table where column = part,
query speed is great, however, changing the where clause to "where column
like 'part%'" the explain analyze shows the database doing a full table scan
and not utilzing the index which slows the query speed.

Oracles optimizer, on the other hand, will use the index so that there is no
comparison in terms of query speed...

How can I get Postgresql's optimizer to use the index?