The following bug has been logged online:
Bug reference: 6082
Logged by: Steve Haslam
Email address: araqnid@googlemail.com
PostgreSQL version: 9.0.4
Operating system: Debian GNU/Linux (amd64)
Description: server segfault - pg_stat_reset_shared(null)
Details:
=> select pg_stat_reset_shared(null)
*server segfault*
Also occurs with a 9.1b2 build.
To be fair, it *does* reset all the shared statistics.