Premigration Assesment test on DMS Task

Hi Suresh,

1. To turn on logical replication in RDS for PostgreSQL, modify a custom parameter group to set rds.logical_replication to 1 and attach it to the DB instance. Update the parameter group to set rds.logical_replication to 1 if a custom parameter group is attached to a DB instance. The rds.logical_replication parameter is a static parameter that requires a DB instance reboot to take effect. When the DB instance reboots, the wal_level parameter is set to logical [1]. Please ensure that the source database has been rebooted after the parameter was changed.

   You can verify the values for wal_level and rds.logical_replication by running the below query in the source database:

  postgres=> SELECT name,setting FROM pg_settings WHERE name IN ('wal_level','rds.logical_replication');

2. The shared_preload_libraries parameter is also a static parameter. After pglogical has been added to the shared_preload_libraries, please reboot the RDS instance for the parameter to take effect.

   Please note that the pre-migration assessment "Check if the source database is configured for PGLOGICAL" verifies if the shared_preload_libraries value is set to pglogical to support PGLOGICAL for CDC. Note that you can ignore this assessment if you are planning to use test decoding for logical replication [2].

References:

[1] https://repost.aws/knowledge-center/rds-postgresql-use-logical-replication

[2] https://docs.aws.amazon.com/dms/latest/userguide/CHAP_Tasks.AssessmentReport.PG.html#CHAP_Tasks.AssessmentReport.PG.pglogical