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How does logical replication of a table work?
Logical replication of a table typically starts with taking a snapshot of the data on the publisher database and copying that to the subscriber. Once that is done, the changes on the publisher are sent to the subscriber as they occur in real-time.
How does logical replication work in azure database?
PostgreSQL’s logical replication and logical decoding features are supported in Azure Database for PostgreSQL – Flexible Server, for Postgres version 11. Logical replication and logical decoding have several similarities. They both use logical replication slots to send out data. A slot represents a stream of changes.
How does logical replication work in Amazon RDS?
The initial data in existing subscribed tables is used to create a snapshot and is transferred to the subscriber via the COPY command. The initial sync worker at the subscriber receives the snapshot, maps the payload within snapshot to local tables, and applies the required operations.
Why are my logical replication slots not available?
Slots and HA failover – Logical replication slots on the primary server are not available on the standby server in your secondary AZ. This applies to you if your server uses the zone-redundant high availability option. In the event of a failover to the standby server, logical replication slots will not be available on the standby.
How is pglogical replication replicated in real time?
The changes made to the tables part of pglogical replication are replicated in real-time via WAL records which makes it highly efficient and non complex. All of the other replication mechanisms in the market are trigger based which can pose performance and maintenance challenges.
Which is the first step in PostgreSQL logical replication?
Step 1: A snapshot of the publishing database is copied to the subscriber. This step is also called the table synchronization phase. To reduce the amount of time spent in this phase, you can spawn multiple table synchronization workers. However, you can only have one synchronization worker for each table.
What’s the difference between logical replication and Wal based replication?
Logical Replication or Pglogical is a table level, WAL based replication mechanism which replicates the data of specific Tables between two PostgreSQL instances. There seems to be a confusion between “pglogical” and “Logical Replication”. Both of them provide the same kind of replication mechanism with some differences in features and capabilities.
Are there any limitations to logical replication in PostgreSQL?
Logical Replication has some limitations on which the community is continuously working on to overcome: Tables must have the same full qualified name between publication and subscription. Mutual (bi-directional) Replication is not supported
Can a table be replicated in multiple publications?
Multiple tables can be added to a single publication and a table can be in multiple publications. You should add objects explicitly to a publication except if you choose the “ALL TABLES” option which needs a superuser privilege. You can limit the changes of objects (INSERT, UPDATE, and DELETE) to be replicated.
Can you limit the changes of objects to be replicated?
You can limit the changes of objects (INSERT, UPDATE, and DELETE) to be replicated. By default, all operation types are replicated. You must have a replication identity configured for the object that you want to add to a publication. This is in order to replicate UPDATE and DELETE operations.