This should be used wherever we need to show the latest release
date.
Don't use this in the release notes however, as it will be easy to
forget to update it when adding notes for a new release.
Use &repmgrversion; entity to generate the current version number and
prevent document bitrot.
Also define a "release-current" ID attribute for ease of linking to
the current release notes.
Per notification from the mailing list.
Previously, repmgr was using a very simple ad-hoc string-based parser,
which had various limitations and allowed configuration files to be
created in a way which could cause confusion and/or unexpected
behaviour.
For example, it accepted strings enclosed in single quotes, but treated
strings enclosed in double quotes literally. A node_name defined thusly:
node_name="somenode"
would result in the literal value '"somenode"' being used, which could
lead to unobvious errors along the lines of:
no record found for ""somenode""
The configuration file parser has been adapted from the one used by
PostgreSQL itself, so behaves more-or-less identically (though some
functions such as file inclusion are not supported in repmgr).
This makes configuration parsing more robust and consistent;
additionally, error reporting will be more precise.
Note this does mean that some repmgr.conf items previously accepted
as valid by repmgr will now be rejected; in particular this includes
strings containing spaces which are not enclosed in single quotes.
While it's technically possible to have a standby follow another
standby while the primary is not available, repmgr will not be able
to update its metadata, which will cause Confusion and Chaos.
Update the documentation to make this clear, and provide a more helpful
error message if this situation occurs. The operation previously
failed anyway, but with an unhelpful message about not being able to
find a node record.
This helps provide a better picture of the state of the cluster, i.e.
making it more obvious whether there's been a timeline divergence.
This also provides infrastructure for further improvements in cluster
status display and diagnosis.
Note this is only available in PostgreSQL 9.6 and later as it relies
on the SQL functions for interrogating pg_control, which can be executed
remotely. As PostgreSQL 9.5 will shortly be the only community-supported
version without these functions, it's not worth the effort of trying
to duplicate their functionality.
Previously repmgr would happily clone from whatever server
it found at the provided source server address. We should
ensure that a standby can only be cloned from a node which
is part of the main replication cluster.
This check fetches a list of nodes from the source server,
connects to the first non-witness server it finds, and
compares the system identifiers of the source node and the
node it has connected to. If there is a mismatch, then the
source server is clearly not part of the main replication
cluster, and is most likely the witness server.
When showing node information, check if the node's copy of its
record shows a different upstream to the one expected according
to the node where the command is executed.
This helps visualise situations where the cluster is in an
unexpected state, and provide a better idea of the actual state.
For example, if a cluster has divided somehow and a set of nodes are
following a new primary, when running "cluster show" etc., repmgr
will now show the name of the primary those nodes are actually
following, rather than the now outdated node name recorded
on the other side of the split. A warning will also be issued
about the situation.
This brings the repmgr documentation build system in line with that
used by the main PostgreSQL project, and removed the restriction
that documentation must be built against PostgreSQL 9.6 or earlier.
Main formatting changes are:
- convert empty-element tags (mainly <xref/>)
- put <indexterm> sections in the correct location
- correct usage of various entities.
It's not attached to the primary per-se, but needs to know what
the current primary is in order to correctly synchronise its
copy of the metadata.
Per GitHub #560.
Ian Barwick