Announcing Release 5 of the PostgreSQL Buildfarm Client

Release 5 of the PostgreSQL Buildfarm Client has been released and can
be downloaded from
<https://buildfarm.postgresql.org/downloads/releases/build-farm-5.tgz>

In a similar move to PostgreSQL version numbering, with this release we
move to a one part numbering system.

In addition to a number of bug fixes and very minor changes, this
release has the following features / changes:

* Cross-version pg_upgrade module is no longer experimental - see below
* TAP tests now run the "check" target, but in most cases redundant
installs are avoided
* Improved and expanded TAP test running on MSVC animals - these now
run the same tests as other animals
* Automatic garbage collection of git repositories, once a week by
default. This should improve the speed of git operations, especially
on older git releases.
* Improve logging in SEpgsql module
* Revert 4.19 setting of TZ by default. If you want it set then do so
in the config file. Doing so can speed up initdb. Setting it by
default caused too many anomalies.
* The environment setting BF_LOG_TIME (settable in the config file)
causes command output to be prefixed with a timestamp on Unix
platforms if /usr/bin/ts is present.

The cross-version upgrade module (TestUpgradeXVersion) has long been an
experimental module. It has been refactored and set to report its
results properly to the server, so it's now ready for wider use. Its use
requires quite a lot of disk space, so it's not configured by default.
You need to have at least 5Gb of available space in order to use it.
Normally in a buildfarm run all the build products are removed. This
module saves them in a special area so that they are available for
testing against different branches. Each branch is tested against itself
and any earlier branches that the module has saved. So currently for the
HEAD (i.e. master) branch it can test upgrades from 9.2, 9.3, 9.4, 9.5
and 9.6 as well as itself. The tests cover all the databases in the
install, such as each contrib database, not just the standard regression
database. The module has a heuristic test for success. Once the upgrade
has run successfully, we compare a pre-upgrade dump with a post-upgrade
dump. If it's a same branch upgrade we expect 0 lines of difference, but
for a cross-branch upgrade we allow up to 2000 lines of difference.
Clearly this isn't a perfect test, but experience with the module over
an extended period has shown that pretty much all problems either result
in an upgrade failure or a diff that is larger than 2000. See
<https://buildfarm.postgresql.org/cgi-bin/show_stage_log.pl?nm=crake&dt=2017-06-13%2012%3A55%3A45&stg=xversion-upgrade-REL9_2_STABLE-HEAD>
for an example of output in upgrading REL9_2_STABLE to HEAD. The tests
take about 60 to 90 seconds per test on my test machine - so in a full
buildfarm run across all live branches (21 upgrade tests in all) that
adds about 30 minutes.

cheers

andrew