Replication set membership v5.6

Suggest edits

bdr.replication_set_add_table

This function adds a table to a replication set.

This function adds a table to a replication set and starts replicating changes from the committing of the transaction that contains the call to the function. Any existing data the table might have on a node isn't synchronized. Replication of this command is affected by DDL replication configuration, including DDL filtering settings.

Synopsis

bdr.replication_set_add_table(relation regclass,
                              set_name name DEFAULT NULL,
                              columns text[] DEFAULT NULL,
                              row_filter text DEFAULT NULL)

Parameters

  • relation — Name or Oid of a table.
  • set_name — Name of the replication set. If NULL (the default), then the PGD group default replication set is used.
  • columns — Reserved for future use (currently does nothing and must be NULL).
  • row_filter — SQL expression to use for filtering the replicated rows. If this expression isn't defined (that is, it's set to NULL, the default) then all rows are sent.

The row_filter specifies an expression producing a Boolean result, with NULLs. Expressions evaluating to True or Unknown replicate the row. A False value doesn't replicate the row. Expressions can't contain subqueries or refer to variables other than columns of the current row being replicated. You can't reference system columns.

row_filter executes on the origin node, not on the target node. This puts an additional CPU overhead on replication for this specific table but completely avoids sending data for filtered rows. Hence network bandwidth is reduced and overhead on the target node is applied.

row_filter never removes TRUNCATE commands for a specific table. You can filter away TRUNCATE commands at the replication set level.

You can replicate just some columns of a table. See Replicating between nodes with differences.

Notes

This function uses the same replication mechanism as DDL statements. This means that the replication is affected by the DDL filters configuration.

If the row_filter isn't NULL, the function takes a DML global lock on the relation that's being added to the replication set. Otherwise it takes just a DDL global lock.

This function is transactional. You can roll back the effects with the ROLLBACK of the transaction. The changes are visible to the current transaction.

bdr.replication_set_remove_table

This function removes a table from the replication set.

Replication of this command is affected by DDL replication configuration, including DDL filtering settings.

Synopsis

bdr.replication_set_remove_table(relation regclass,
                                 set_name name DEFAULT NULL)

Parameters

  • relation — Name or Oid of a table.
  • set_name — Name of the replication set. If NULL (the default), then the PGD group default replication set is used.

Notes

This function uses the same replication mechanism as DDL statements. This means the replication is affected by the DDL filters configuration.

The function takes a DDL global lock.

This function is transactional. You can roll back the effects with the ROLLBACK of the transaction. The changes are visible to the current transaction.

← Prev

Replication set management

↑ Up

PGD reference

Next →

DDL replication filtering