RDS Postgres + cluster + pglogical?

Question

I have an on-prem database which I am trying to replicate (using `pglogical`) to RDS, preferably an RDS cluster.

I was able to replicate to a "Single DB instance" , by setting `rds.logical_replication` in the parameter group, but my question is whether I can replicate to a "Multi-AZ DB Cluster"'s writer.

When I create the cluster, I notice that the setting `rds.logical_replication` is not available in the "DB Cluster Parameter Group".  Is there an equivalent setting for a cluster? I was able to add pglogical to `shared_preload_libraries` in the DB Cluster Parameter Group, but I'm not sure if all of the settings I need are available.

Since starting down this journey, it seems that Postgres 14.2 is not available for the cluster, so my question is not as critical. But I'd still like to know, because we might want to use a cluster once 14.2 is available.

Thanks for any help.

Answer

Hi,

I understand that you want to know if there is a workaround to replicate to Multi-AZ DB Cluster’s writer. Please correct me if I misunderstood.

From the post, I see you are not able to replicate with Multi-AZ DB cluster’s writer instance. This is due to RDS for PostgresSql Multi-AZ Db clusters not supporting logical replication hence you could not find the rds.logical_replication on the parameter groups that also includes pglogical extention.
Please refer on the link[1] below to check the settings that are available for your pglogical extention. There is a logical replication option available but with Aurora PostgreSQL version 2.2.0(compatible with PostgreSQL 10.6)[2]. Note that to perform the logical replication for a PostgreSQL database, your AWS user account would need the rds_superuser role. I have also included a link below on limitations for Multi-AZ DB clusters[3]. For the updates on the PostgreSql versions, please see the doc[4].

I hope the above answers your questions.

References:

[1]https://aws.amazon.com/blogs/database/migrating-postgresql-from-on-premises-or-amazon-ec2-to-amazon-rds-using-logical-replication/

[2]https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/AuroraPostgreSQL.Replication.Logical.html

[3]https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/multi-az-db-clusters-concepts.html#multi-az-db-clusters-concepts.Limitations

[4] https://docs.aws.amazon.com/AmazonRDS/latest/PostgreSQLReleaseNotes/postgresql-versions.html

RDS Postgres + cluster + pglogical?

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