CREATE PUBLICATION replication1 ALTER PUBLICATION replication1 ADD TABLE mytbl Replicate to the first EC2 instance: create database bhuvi \c bhuvi create table mytbl (id int PRIMARY KEY, name varchar(10)) create table mytbl_new (id int PRIMARY KEY, name varchar(10)) insert into mytbl values (1, 'postgresql') insert into mytbl values (2, 'mysql') insert into mytbl values (3, 'sqlserver') insert into mytbl_new values (1, 'aws') insert into mytbl_new values (2, 'rds') insert into mytbl_new values (3, 'aurora')
Port 5432 should be opened between the RDS and the EC2.Ĭreate a sample database and add 2 tables with some values. Make sure then wal_level=logical in the config file. Because we are trying to simulate that the RDS is already having logical replication. #Aws postgresql dump ec2 install
Launch 2 new EC2 instances and install PostgreSQL 10. On the Target database, set rds.logical_replication=1 and shared_preload_libraries = 'pglogical' in the database parameter group. You can use the same method to replicate RDS to RDS without performing the initial COPY. Finally, enable the Subscription to resume the CDC from the Master node. Manually advance the replication slot on Target to set the last LSN as the value that we copied from the log file. Create a new subscription on Target(with disabling mode) that will be pointing the slot and publication of the one on the source which we created for this CDC. Once the sync has been done, disable the subscription. Then create the subscription on your Target. Create a publication on the Snapshot RDS. Go to the log file most recent one, or before the recent one, get the LSN number. So take a snapshot and restore it as a new RDS instance. The pg_replication_slots will mark the LSN of WAL which still might be required for the subscriber. Until a subscriber consumes it’ll be persisted. When you created the Publication and added the table, then all the write operations will be tracked in your replication slot. But this Logical Replication changed everything. When this feature was not available on RDS, we used trigger-based replications with Bucardo, Slony to migrate. If you want to replicate from/to RDS, then the native streaming replication will not help you, also it's not possible. PostgreSQL’s replication is not like MySQL. Importance of Logical Replication in RDS: But if your RDS instance already having any replication slots then? Also here the requirement is RDS to an external replica. If you are already familiar with RDS and Logical replication and you may recently read a blog post from instacart. So we did Proof Of Concept to solve this issue with Snapshots. 
We can’t do read from Read Replica, logical replication only works on the master node. This may reduce the performance of the master node. If you have a mission-critical database on AWS RDS PostgreSQL, then the logical replication will start COPY from the Master node. Generally in a logical replication once the subscriber is enabled, CDC will be captured in the logical replication slots and also it’ll start sync the historical data(initial sync) from the Publisher itself with the COPY process. RDS PostgreSQL Logical Replication COPY from AWS RDS SnapshotĪWS RDS PostgreSQL has logical replication enabled from 9.4+ onwards.
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