What do people like to monitor (or in other words, what might be nice in pgsnmpd)?

Work is beginning on pgsnmpd v 2.0, and I figured it would be a good
time to ask folks what they typically like to monitor, so we can make
sure pgsnmpd instruments it properly. The current version of pgsnmpd
supports something called RDBMS-MIB, which is a set of data designed
to be applicable to any relational database, so it doesn't get very
PostgreSQL-specific. The next version will augment that with
PGSQL-MIB, which we have yet to write.

PGSQL-MIB should contain data elements for, ideally, anything specific
to the database that someone could possibly want to monitor in a
generic PostgreSQL installation within reason. Things like CPU load,
available disk space, total system memory, etc. would not be included,
because they're not PostgreSQL specific, but things like CPU and
memory usage of individual PostgreSQL processes are very good
candidates for inclusion in PGSQL-MIB. Current plans have us including
SNMP representations of all the statistics tables as well as the
system catalogs, runtime information about PostgreSQL processes (such
as CPU and RAM usage), shared memory usage information, and
potentially mechanisms to easily include administrator-specified
queries and generate SNMP traps based on LISTEN/NOTIFY.

So please respond, if you feel so inclined, describing things you like
to monitor in your PostgreSQL instances as well as things you would
like to be able to easily monitor in a more ideal world. Many thanks,
and apologies for any breach of netiquette I may have committed in
posting to two lists simultaneously.

- Josh Tolley