aptible db:replicate

This command is used to create a replica of an existing Database.

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Note

Review Database Replication and Clustering before creating a replica.

Examples

Create a replica with a custom Disk Size

aptible db:replicate "$DB_HANDLE" "$REPLICA_HANDLE" \
            --disk-size 20

Create a replica with a custom Container Size

aptible db:replicate "$DB_HANDLE" "$REPLICA_HANDLE" \
            --container-size 2048

Create a replica with a custom Container and Disk Size

aptible db:replicate "$DB_HANDLE" "$REPLICA_HANDLE" \
            --container-size 2048 \
            --disk-size 20

Create an upgraded replica for logical replication

aptible db:replicate "$DB_HANDLE" "$REPLICA_HANDLE" \
            --logical --version 12

Synopsis

Usage:
  aptible db:replicate HANDLE REPLICA_HANDLE [--container-size SIZE_MB] [--disk-size SIZE_GB] [--logical --version VERSION] [--key-arn KEY_ARN]

Options:
  [--environment=ENVIRONMENT]
  [--container-size=N]
  [--size=N]
  [--disk-size=N]
  [--logical], [--no-logical]
  [--version=VERSION]
  [--key-arn=KEY_ARN]

Create a replica/follower of a database

How Logical Replication Works

aptible db:replicate --logical should work in most cases. This section provides additional details details on how the CLI command works for debugging or if you'd like to know more about what the command does for you.

The CLI command uses the pglogical extension to set up logical replication between the existing Database and the new replica Database. At a high level, these are the steps the CLI command takes to setup logical replication for you:

  1. Update max_worker_processes on the replica based on the number of PostgreSQL databases being replicated. pglogical uses several worker processes per database so it can easily exhaust the default max_worker_processes if replicating more than a couple of databases.
  2. Recreate all roles (users) on the replica. pglogical's copy of the source database structure includes assigning the same owner to each table and granting the same permissions. The roles must exist on the replica in order for this to work.
  3. For each PostgreSQL database on the source Database, excluding those that beginning with template:
    1. Create the database on the replica with the aptible user as the owner.
    2. Enable the pglogical extension on the source and replica database.
    3. Create a pglogical subscription between the source and replica database. This will copy the source database's structure (e.g. schemas, tables, permissions, extensions, etc.).
    4. Start the initial data sync. This will truncate and sync data for all tables in all schemas except for the information_schema, pglogical, and pglogical_origin schemas and schemas that begin with pg_ (system schemas).

The replica does not wait for the initial data sync to complete before coming online. The time it takes to sync all of the data from the source Database depends on the size of the Database.

When run on the replica, the following query will list all tables that are not in the replicating state and, therefore, have not finished syncing the initial data from the source Database.

SELECT * FROM pglogical.local_sync_status WHERE NOT sync_status = 'r';

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