PostgreSQL Constraints

Table 1 shows the constraints designed to ensure the stability and security of RDS for PostgreSQL.

**Table 1** Function constraints
Function Item	Constraints
Database access	If public accessibility is not enabled, the RDS DB instance must be in the same VPC as the ECS. RDS read replicas must be created in the same subnet as the primary DB instance. The security group must allow access from the ECS. By default, RDS cannot be accessed through an ECS in a different security group. You need to add an inbound rule to the RDS security group. The default RDS port is 5432. You can change it if you want to access RDS through another port.
Deployment	ECSs in which DB instances are deployed are not visible to users. You can access the DB instances only through an IP address and a port number.
Database root permissions	Only the root user permissions are provided on the instance creation page.
Database parameter modification	Most parameters can be modified on the RDS console.
Data import	Through the psql CLI tools
Database replication setup	RDS for PostgreSQL uses a primary/standby dual-node replication cluster. You do not need to set up replication additionally. The standby DB instance is not visible to users and therefore you cannot access it directly.
DB instance reboot	DB instances cannot be rebooted through commands. They must be rebooted through the RDS console.
RDS backup files	RDS backup files are stored in OBS buckets and are not visible to users.