The "data_checksum_version" field towards the end of the ControlFileData struct,
meaning its position varies between versions. Previously this wasn't a problem
as it was only required for operations involving 9.5 and later, and its position
within the control file has not changed between the current release and current
HEAD.
However, in order to support pg_rewind in 9.3 and 9.4, which both have changes in
the control file format, we'll need version-specific parsing. This will also make
it easier to deal with any future changes to the control file format.
pg_rewind is not part of the core distribution for those, but we
provided support in repmgr 3.3 so should extend it to repmgr 4.
Note that there is no check in place whether the pg_rewind binary
exists, so it's up to the user to ensure it's present.
Addresses GitHub #413.
If two nodes were in the primary location, and at least one node in
another location, the non-failed node in the primary location was not
recognising itself as a promotion candidate.
Addresses GitHub #407.
This file will collate various requests and ideas for future developement.
In particular it will reference requests which come in via the GitHub issue
tracker, so we can acknowledge and close off the request and not have an
open unresolved issue hanging around.
Addresses issue described in GitHub #378.
PostgreSQL itself doesn't issue a checkpoint after promotion to ensure
the newly promoted server is available as quickly as possible, so we'll
only execute an explicit CHECKPOINT when it's actually required, i.e.
when pg_rewind will be executed. This is required as pg_rewind uses
the timeline reported in the pg_control file to compare with the
server to be rewound, and the pg_control timeline is only updated after
the first checkpoint, so there is an interval where pg_rewind will
erroneously assume both servers are on the timeline and take no action.
During a switchover operation, once the demoted primary has been restarted
as a standby, repmgr attempts to reconnect to verify its status and drop
any redundant replication slots. However it's possible the standby may still
be in the startup phase, so poll for "standby_reconnect_timeout" seconds
before giving up.
Addresses GitHub #408.
When executing a command on a remote server, repmgr expects the remote binary
to be in the same location as the local binary. It's reasonable to assume
repmgr will be deployed in a unified environment; if not, the onus is on the
user to ensure repmgr can find the remote binary, e.g. by creating appropriate
symlinks.
Addresses query in GitHub #406.
Insert "connect_timeout=2" into the connection parameters, if not
explicitly set by the user. This will prevent excessive wait time
for the host operating system to report a connection timeout.
When parsing conninfo strings, ensure the error message pointer is
actually returned to the caller.
Not a criticial issue, just meant the contents of the error message
were not being displayed.
get_superuser_connection() was erroneously using the local node record
to connect to as a superuser, which works when registering the primary
but obviously not when cloning a standby.
Addresses GitHub #380.
This is used for determining a timeout when reconnecting to the standby
after executing the "follow_command". This will normally not need to be
set explicitly, but maybe useful in cases where the standby's startup
phase can last longer than usual.
Ian Barwick