Specifically, don't attempt to disable walsenders if "standby_disconnect_on_failover"
is "true", but the repmgr user is not a superuser.
This restriction can be lifted from PostgreSQL 15.
Information about using repmgr with a non-superuser was spread
throughout individual documentation systems; this commit creates
an overview of requirements and potential issues.
Previously, if the witness node's PostgreSQL was unreachable, it would
be marked as "inactive" on the primary, and under some circumstances
would not be corrected to "active" once the witness node's PostgreSQL
came back.
PR #754; some modifications by Ian Barwick.
The cluster size check is purely informative, and is not in any way
essential for the standby clone operation. As it's possible the query
may fail if the repmgr user does not have sufficient privileges to
query all databases in the cluster, we can simply ignore any failure.
Note that the code comment indicated the query also served to sanity-
check that queries can actually be executed. While this was the case
historically, the preceding server version check now serves the same
purpose and will not have the same risk of failure due to missing
permissions.
Explicitly check whether the "repmgr node rejoin" command on the
demotion candidate succeeded. Due to the way SSH execution is
currently implemented, we can return either the command execution
status or the command output; to ensure any errors are available,
log them to a temporary file on the demotion candidate and note
its location in case of an error.
While we're at it, improve error message handling when the demotion
candidate fails to rejoin.
Unfortunately it hasn't been possible yet to include all available
configuration items in the main documentation, but we should at least
make it easier to find the full list.
If a PostgreSQL instance was shut down while repmgrd was running, and
repmgrd was subsequently restarted (this chain of events could occur
during e.g. a server reboot), the node record will have been set to
"inactive". Previously, in this case repmgrd would refuse to start up.
However, as we can determine the node is running, it should normally
be no problem to automatically set the node record to "active".
The old behaviour can be restored by setting the new parameter
"repmgrd_exit_on_inactive_node" to "true".
RM19604.
