Compatibility changes
=====================

Summary
-------

There are some changes in PGD Version 6.4 that are not compatible with
5.x and other previous versions. For users of 4.x, the 
`version 5.x compatibility <https://www.enterprisedb.com/docs/pgd/5.8/upgrades/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 :ref:`Connection Manager Authentication <Connection Manager Authentication>`  .

DDL Locking changes
-------------------

There is a new global lock type, ``ddl_locking = leader`` that’s used by
PGD Version 6.4 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). ``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 :ref:`Sequences <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_config()`` 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 :ref:`Relationship to automatic synchronization <Relationship to automatic synchronization>`  . It enables changes from a down node to
be synced to all other nodes.