how to (temporarily) disable/minimize benefits of disk block cache or postgresql shared buffer

Hi,

this is not really a performance question , sorry if its bit irrelevant
to be posted here. We have a development environment and we want
to optimize the non-database parts of the application. The problem is
that subsequent run of  queries are execute very fast and makes the
performance analysis a trivial problem. We want that the subsequent runs
of query should take similar times as the first run so that we can work
on the optimizing the calling patterns to the database.

regds
Rajesh Kumar Mallah.