According to the docs is specifically doesn't.
http://www.postgresql.org/docs/7.4/static/sql-prepare.html
When the PREPARE statement is executed, the specified statement is
parsed, rewritten, and planned. When an EXECUTE command is subsequently
issued, the prepared statement need only be executed. Thus, the parsing,
rewriting, and planning stages are only performed once, instead of every
time the statement is executed.
Markus Bertheau wrote:
> On Fri, 27 Aug 2004 11:09:26 -0400, Joseph Shraibman
> <jks@selectacast.net> wrote:
>
>
>> How does EXECUTE solve the cached-plan business?
>
>
> It re-plans the query at every run.
>