Configurando publicações

Welcome! In PostgreSQL logical replication, a publication is like a channel on the master server that broadcasts data changes.

It defines what data (which tables) and which operations (INSERTs, UPDATEs, DELETEs, TRUNCATEs) should be replicated to subscribing servers.

Think of it as setting up a TV station: you decide which shows to broadcast and when.

Creating a publication is straightforward using the CREATE PUBLICATION command. Let's start with the simplest form.

This creates a publication that doesn't publish any tables yet, but it's ready to be configured.

If you want to replicate all tables in your current database (and any new ones created later), you can use the FOR ALL TABLES clause.

This is handy for replicating an entire database schema.

Often, you only need to replicate a subset of tables. You can specify these tables directly using the FOR TABLE clause.

This publication will only broadcast changes from the users and products tables.

There's a key difference between FOR ALL TABLES and listing tables with FOR TABLE:

• FOR ALL TABLES: Dynamically includes all current and future tables in the database.
• FOR TABLE table1, table2: Statically lists specific tables. New tables must be added manually.

Choose based on your replication needs!

Publications can be configured to replicate only certain types of data modifications. By default, INSERT, UPDATE, DELETE, and TRUNCATE are replicated.

You can use the WITH (publish = '...') clause to select specific operations. Here, we only replicate INSERT statements.

To replicate multiple, but not all, operation types, you can list them separated by commas within the publish option.

This publication will replicate INSERT, UPDATE, and DELETE operations, but not TRUNCATE.

Want to see what publications are active on your server? PostgreSQL stores this information in its system catalogs.

You can query the pg_publication view to get details about each publication, including what operations it publishes.

You can modify an existing publication to add or remove tables, or even drop it entirely if it's no longer needed.

• ALTER PUBLICATION ADD TABLE: Add tables.
• ALTER PUBLICATION DROP TABLE: Remove tables.
• DROP PUBLICATION: Delete a publication.

Which of the following statements correctly configure a publication in PostgreSQL?

Great job! You've learned how to define publications in PostgreSQL.

• Publications broadcast data changes for logical replication.
• Use CREATE PUBLICATION to define them.
• You can publish FOR ALL TABLES or FOR TABLE specific_tables.
• The WITH (publish = '...') clause lets you select specific operations (insert, update, delete, truncate).
• You can manage them with ALTER PUBLICATION and DROP PUBLICATION.

Next, we'll learn how to set up subscriptions to receive these changes!