Greg's Postgres stuff

This looks interesting: a community-organized database conference. Not just the Postgres community, but inclusive of all database communities as well (Yes, other database systems have communities as well, although none are as good as the Postgres one . From Baron's blog post:

Version 2.9.0 of DBD::Pg has been released. In addition to lots and lots of work lately on the test suite and the docs (view the latest webified version of the POD doc here), I came across an unused database attribute called "ReadOnly". From the DBI docs:

An application can set the ReadOnly attribute of a handle to a true value to indicate that it will not be attempting to make any changes using that handle or any children of it.

This looked like a great chance to use the seldom known READ ONLY transaction mode. From the Postgres docs:

Robert Treat had a great idea for a new action (which we've named autovac_freeze) for the check_postgres.pl program. This action will alert you when any of your databases are approaching the limit set by the autovacuum_freeze_max_age parameter. In a nutshell, this sets the point at which autovacuum will kick in and vacuum any tables that have exceeded this value, which defaults to 200 million. This is a new parameter as of 8.2. Reading the full documentation on preventing transaction wraparounds is a must for Postgres DBAs, even though it can be a little difficult to understand the first few reads.

This version also adjusts the txn_wraparound action a little bit, so that it outputs the databases in highest to lowest numbers of transactions. As always, grab the latest version of check_postgres.pl at http://bucardo.org/check_postgres/.

I just released version 2.0.1 of the check_postgres.pl program. While in the past this script was strictly for use as a Nagios plugin, it now features two additional output modes. While Nagios is still the default, you can now ask for MRTG and "simple" output by using the --output= option. The MRTG option outputs four lines of information, with the first always being a simple number. The "simple" output mode simply outputs the first line of the MRTG output - in other words, a single number, nothing more and nothing less. This is very useful for times when you just want to check the state of something without worrying about setting warning limits, querying exit codes, etc. See the the documentation for complete details.

This version also greatly speeds up the "check_bloat" action, which gives a rough estimate of how bloated the tables and indexes in your database are. Rather than use a large regex to parse the output, it now simply does a split. Kudos goes to the new version of the Devel::NYTProf module, which pointed out that particular bottleneck quite easily (and colorfully!).

New ideas and patches always welcome, just mail the list or play around with the git repository.

There are now two mailing lists to support the check_postgres.pl project. Please sign up if you are interested in following the development, want to discuss usage, or want quick notifications of new versions. The two lists are:

• check_postgres - general discussion
• check_postgres-announce - low volume: new releases and other important news

Commit diffs will also be posted to the general mailing list. Version 1.8.4 was just released today, and has a minor fix for the replication_row action. Another recent fix was to the backends check, to fix a race condition in which Postgres reports no rows in pg_stat_activity (obviously there must be at least one, yourself, but in some versions of Postgres the process that updates the entries in pg_stat_activity may not have run before you query it).