Release notes for EDB Postgres Distributed version 4.0.2 v4

This changes the handling of the backoff delay to exponentially increase from bdr.min_worker_backoff_delay to bdr.max_worker_backoff_delay in presence of repeated errors. This reduces log spam and in some cases also prevents unnecessary connection attempts.

This allows optional queueing of ddl commands for replication to other groups without executing it locally.

The reporting of these transient errors was confusing as they were also shown in bdr.worker_errors. These are now changed to WARNINGs.

Confirm end LSN of the running transactions record processed by WAL decoder so that the WAL decoder slot remains up to date and WAL senders get the candidate in timely manner.

When a node has started parting process, it makes no sense to wait for autopartition tasks on such nodes to finish since it's not part of the group anymore.

Nodes now have a generation number so that it's easier to identify the name reuse even if the node record is received as part of a snapshot.

When processing multiple actions in the state machine, make sure to reacquire the lock on the processed node and update the snapshot to make sure all updates happening through consensus are taken into account.

Drop all groups, not only the primary one and drop all the node state history info as well.

Previously bdr_init_physical would simply wait forever when there was any issue with the consensus request, now we do same checking as the logical join does.

This reduces the amount of new consensus votes needed when processing many consensus requests or time consuming consensus requests, for example during join of a new node.

The wal_receiver_timeout has not been triggered correctly due to a regression in BDR 3.7 and 4.0.

Otherwise flush progress is not reported in presence of disconnected nodes when using bdr.standby_slot_names.

HARP offers multiple options for Distributed Consensus Service (DCS) source: etcd and BDR. The BDR consensus option can be used in deployments where etcd isn't present. Use of the BDR consensus option is no longer considered beta and is now supported for use in production environments.

HARP offers multiple proxy options for routing connections between the client application and database: application layer (L7) and transport layer (L4). The network layer 4 or transport layer proxy simply forwards network packets, and layer 7 terminates network traffic. The transport layer proxy, previously called simple proxy, is no longer considered beta and is now supported for use in production environments.