Known issues v5
These are currently known issues in EDB Postgres Distributed 5. These known issues are tracked in PGD's ticketing system and are expected to be resolved in a future release.
If the resolver for the
update_origin_changeconflict is set to
synchronous_commit=remote_applyis used, and concurrent updates of the same row are repeatedly applied on two different nodes, then one of the update statements might hang due to a deadlock with the PGD writer. As mentioned in Conflicts,
skipisn't the default resolver for the
update_origin_changeconflict, and this combination isn't intended to be used in production. It discards one of the two conflicting updates based on the order of arrival on that node, which is likely to cause a divergent cluster. In the rare situation that you do choose to use the
skipconflict resolver, note the issue with the use of the
The Decoding Worker feature doesn't work with CAMO/Eager/Group Commit. Installations using CAMO/Eager/Group Commit must keep
Lag Control doesn't adjust commit delay in any way on a fully isolated node, that is, in case all other nodes are unreachable or not operational. As soon as at least one node is connected, replication Lag Control picks up its work and adjusts the PGD commit delay again.
For time-based Lag Control, PGD currently uses the lag time (measured by commit timestamps) rather than the estimated catchup time that's based on historic apply rates.
Changing the CAMO partners in a CAMO pair isn't currently possible. It's possible only to add or remove a pair. Adding or removing a pair doesn't need a restart of Postgres or even a reload of the configuration.
Transactions using Eager Replication can't yet execute DDL. The TRUNCATE command is allowed.
Parallel apply isn't currently supported in combination with Group Commit. Make sure to disable it when using Group Commit by either:
There currently is no protection against altering or removing a commit scope. Running transactions in a commit scope that's concurrently being altered or removed can lead to the transaction blocking or replication stalling completely due to an error on the downstream node attempting to apply the transaction. Ensure that any transactions using a specific commit scope have finished before altering or removing it.
The PGD CLI can return stale data on the state of the cluster if it's still connecting to nodes that were previously parted from the cluster. Edit the
pgd-cli-config.ymlfile, or change your
--dsnsettings to ensure only active nodes in the cluster are listed for connection.
Details of other design or implementation limitations are also available.