Compatibility changes v6.1.0

Summary

There are some changes in PGD 6.1 that are not compatible with 5.x and other previous versions. For users of 4.x, the version 5.x compatibility changes still apply.

Connection Manager

PGD 6 introduces a new Connection Manager which replaces the PGD 5's proxy solution with a tightly integrated approach using a background worker to expose read-write, read-only and http-status network interfaces in PGD. This means that all the old proxy functions were removed, as there are no longer separate PGD-Proxy instances to manage and the connection manager uses group configuration.

Moreover, bdr.proxy_conifg table and bdr.proxy_config_summary view were removed. You should now use bdr.node_group_config_summary for the connection manager's configuration. This also includes all the other group settings, including routing.

For more details see Connection Manager.

DDL Locking changes

There is a new global lock type, ddl_locking = leader that's used by PGD 6.1 by default instead of the global DML lock. This lock ensures that a table is exclusively locked on all group leaders (as opposed to all nodes). For PGD Essential this means that in practice the lock is engaged immediately as there is only one leader, which means the system exhibits the same behavior as a single node Postgres setup. LOCK TABLE and TRUNCATE TABLE now use this new lock type by default (before the default behavior was to not lock outside of the origin node).

LOCK TABLE now uses DDL lock for ACCESS SHARE, ROW SHARE, ROW EXCLUSIVE, SHARE UPDATE EXCLUSIVE and DML lock for SHARE ROW EXCLUSIVE, EXCLUSIVE, and ACCESS EXCLUSIVE. This means that SHARE+ blocks DMLs, but lower levels don't (which is more closely aligned with how these levels work in Postgres). LOCK TABLE used to always use DML lock.

Join/part behavior

Function and node state changes

For bdr.part_node:

• wait_for_completion works on the local node
• the force option is deprecated and has the same behavior as bdr.drop_node(force:=true)

For bdr.drop_node:

• the cascade option was removed
• force now always immediately drops the node locally and assumes previous cascade behavior as well

For bdr.join_node_group:

• the pause_in_standby option was removed
• now whether the node is in standby is determined by node_kind when running bdr.create_node

A new node state PART_CLEANUP was added, which waits for the group slot to move past any records relevant to the parting node and cleans up origin records related to the node.

Sequences conversion

When creating a PGD cluster, existing sequences are automatically converted to distributed ones.

Parting a node drops it

When a node is parted, it is eventually dropped and the node will not be seen in the PARTED state at the end of the parting. Therefore, scripts that wait for the node to reach PARTED state may need change. Parting can also take longer than earlier versions since this operation waits till the group slot on all crosses of the last transaction from the parting node to ensure consistency.

Administration function changes

• The enable_proxy_routing node group option is now enable_routing, although bdr.alter_node_group_option still supports the older syntax for backwards compatibility. The views only show the new name.
• The already deprecated bdr.alter_node_group_conifg() was removed. Use bdr.alter_node_group_option() instead.
• The managed_locally option in bdr.autopartition() was removed. Only locally managed partitions are now supported. At the same time ap_is_local was removed from bdr.autopartition_rules catalog as well.

Other

Replica identity

• Replica identity defaults to FULL now.
• This removes some edge cases in conflict detection between inserts, updates, and deletes across node crashes and recovery.

Run on (all) writes

• Run on (all) writes is now not replicated.
• The bdr.xact_replicate is set to off by default, reducing possible accidental issues with replication of commands sent via the run on (all) nodes command.
• Some log messages were reworded to be easier to understand.
• Some internal log messages' log levels were lowered from LOG to DEBUG so they may no longer appear in logs.

General UI improvements

• Workers renamed to not contain 'pglogical'
• Previously deprecated configuration parameters (GUCs) now removed (this includes, for example, all the pglogical prefixed GUCs).
• Conflicts are logged neither to Postgres log or conflict_history table by default

Changes to defaults

Global lock timeout

bdr.global_lock_timeout is set to 1 minute by default.

Auto sync

bdr.enable_auto_sync_reconcile is set to ON by default. This feature is documented in Automatic synchronization. It enables changes from a down node to be synced to all other nodes.