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Version: 5.x-preview

Aurora RDS PostgreSQL Source Setup for VeloDB CDC

This guide covers Aurora RDS PostgreSQL configuration for CDC (Change Data Capture) synchronization with VeloDB using Flink CDC.

Supported Versions​

DatabaseVersions
Aurora RDS PostgreSQL13.x, 14.x, 15.x, 16.x

Reference: Aurora PostgreSQL CDC

Enable Logical Replication​

Aurora uses parameter groups instead of direct postgresql.conf editing.

1. Create Parameter Group​

Navigate to RDS > Parameter groups in the AWS Console to view existing parameter groups:

Parameter Groups List

Create a custom cluster parameter group with logical replication enabled:

Create Parameter Group

Important: Select DB Cluster Parameter Group as the type (not DB Parameter Group) for Aurora clusters.

aws rds create-db-cluster-parameter-group \
    --db-cluster-parameter-group-name aurora-pg-cdc \
    --db-parameter-group-family aurora-postgresql16 \
    --description "Aurora PostgreSQL with CDC enabled"

aws rds modify-db-cluster-parameter-group \
    --db-cluster-parameter-group-name aurora-pg-cdc \
    --parameters "ParameterName=rds.logical_replication,ParameterValue=1,ApplyMethod=pending-reboot"

Or configure via AWS Console by editing the parameter group and setting rds.logical_replication to 1:

Edit Parameter Group - rds.logical_replication

2. Apply to Cluster​

aws rds modify-db-cluster \
    --db-cluster-identifier your-cluster-name \
    --db-cluster-parameter-group-name aurora-pg-cdc \
    --apply-immediately

3. Reboot Cluster​

Reboot required for rds.logical_replication to take effect:

aws rds reboot-db-instance --db-instance-identifier your-instance-name

Verify Configuration​

SHOW rds.logical_replication;

Expected result:

 rds.logical_replication
-------------------------
 on
(1 row)

User Permissions​

Aurora requires specific roles instead of SUPERUSER attribute.

Create CDC User​

-- Create user (no REPLICATION or SUPERUSER attributes)
CREATE USER cdc_user WITH LOGIN PASSWORD 'your_password';

-- Grant Aurora-specific roles
GRANT rds_replication TO cdc_user;
GRANT rds_superuser TO cdc_user;
GRANT pg_read_all_data TO cdc_user;

-- Grant database-level permissions
GRANT CONNECT ON DATABASE your_database TO cdc_user;
GRANT ALL ON DATABASE your_database TO cdc_user;

-- Grant schema permissions
GRANT USAGE ON SCHEMA public TO cdc_user;
GRANT SELECT ON ALL TABLES IN SCHEMA public TO cdc_user;
ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT SELECT ON TABLES TO cdc_user;

Required Aurora Roles​

RolePurpose
rds_replicationCreate replication slots and read WAL
rds_superuserManage publications (required for CDC)
pg_read_all_dataRead all tables in all schemas

Note: Aurora master user does NOT have full SUPERUSER privileges. Use roles instead.

Verify User Permissions​

SELECT r.rolname, ARRAY(
    SELECT b.rolname
    FROM pg_catalog.pg_auth_members m
    JOIN pg_catalog.pg_roles b ON (m.roleid = b.oid)
    WHERE m.member = r.oid
) as memberof
FROM pg_roles r
WHERE r.rolname = 'cdc_user';

Expected result:

  rolname  |                     memberof
-----------+--------------------------------------------------
 cdc_user  | {pg_read_all_data,rds_superuser,rds_replication}
(1 row)

Publication Setup​

Create publication as master user (postgres):

-- As postgres user
CREATE PUBLICATION velodb_publication FOR ALL TABLES;

Verify publication:

SELECT * FROM pg_publication WHERE pubname = 'velodb_publication';

Important: Pass --postgres-conf publication.name=velodb_publication to Flink CDC when using Aurora.

REPLICA IDENTITY (Required for DELETEs)​

ALTER TABLE your_table_name REPLICA IDENTITY FULL;

Connection Test​

Verify CDC user can:

  1. Connect:
psql -h your-cluster.cluster-xxxxx.us-west-2.rds.amazonaws.com -p 5432 -U cdc_user -d your_database
  1. List publications:
SELECT * FROM pg_publication;
  1. Read tables:
SELECT COUNT(*) FROM your_table;

Next Steps​

Once Aurora RDS is configured for CDC, follow the Flink CDC Ingestion Guide to set up real-time sync to VeloDB.

Remember to add --postgres-conf publication.name=velodb_publication when running Flink CDC with Aurora.

Sources​