This previously happened in the extension SQL code, which could
potentially cause replay problems if installing on a BDR cluster.
As this table is only required for streaming replication failover,
move the initialisation to "repmgr primary register".
Addresses GitHub #344 .
get_new_primary() returns NULL if no notification for the new primary has
been received, but the code was expecting it to return UNKNOWN_NODE_ID,
which was causing repmgrd to prematurely drop out of the new primary
detection loop if no notification had been received by the time the loop
started.
Also store the electoral term as a single row, single column table,
to ensure that all repmgrds see the same turn. It is then bumped
by the winning node after it gets promoted.
Various logging improvements.
When executing repmgr on remote nodes, we otherwise end up jumping
through hoops as we can't make assumptions about where the configuration
file is located, but really need to be able to provide it.
From a support point of view it will also make life easier as it will
be easy to specify exactly which file to provide.
This will cover both the case when an entire node including
repmgrd goes down, and when one PostgreSQL instance goes down
but repmgrd is still up (in which case only one of the repmgrds
will handle the failover).
When creating recovery.conf outside of "repmgr standby clone",
there was no way of knowing if a replication user had been
explicitly provided with --replication-user, meaning the value
of "primary_conninfo" would be set to the "conninfo" field of the
node's upstream node record.
We'll add an extra column to store the replication user for each
node so it can be referenced at any time.
