From PostgreSQL 12, port.h forcibly redefines printf() et al to use
the versions defined by PostgreSQL (pg_printf() et al). As this
causes linking issues in build environments which build pre-Pg12
versions against Pg12's libpq, ensure relevant macros defined
in port.h are undefined.
This makes it possible to return log output when executing repmgr
remotely at a different level to the one defined in the remote
repmgr's repmgr.conf.
This is particularly useful when DEBUG output is required.
"FullTransactionId" is not present in earlier versions, so we'll
have to #ifdef that out for those.
We should probably add more elegant checks to ensure that repmgr
is being executed against the PostgreSQL version it was built against.
In a normal production environment that will be the case as the
matching package will have been installed, so version mismatches
don't usually occur.
Note that while currently most aspects of the repmgr client are
compatible across PostgreSQL versions, the repmgrd code is very
version specific, so version specificity is a given anyway.
"repmgr daemon" can be interpreted to mean the commands affect the local
daemon process only. Rename the commands which affect the entire cluster
to "repmgr service ...".
The "repmgr daemon ..." form of the affected commands is retained for backwards
compatibility.
Previously, if a standby's repmgrd was looping in degraded monitoring
mode looking for a new primary to follow, once a new primary was
detected the follow command would be executed without any prior
logging at non-DEBUG log levels.
Previously repmgr would emit the "repmgr extension not found on source node"
which depending on context is somewhat misleading, as it may exist
but not be installed, or the user may be attempting to clone from the
wrong database.
From PostgreSQL 10, a member of the default roles "pg_monitor" and/or
"pg_read_all_settings" can read pg_settings without requiring superuser
privileges.
Previously, a hint was being emitted about making the repmgr user a
member of one of those groups, but no check for membership was being
made, meaning the check could only be run by a superuser.
