This topic describes the quotas and limits for ApsaraDB RDS for PostgreSQL. Before you create an ApsaraDB RDS for PostgreSQL instance, make sure that you understand the quotas and limits. This way, you can ensure the stability and security of the created RDS instance.

Specifications and performance

Item Specification Description
Storage capacity
  • RDS instances with local SSDs: up to 6,000 GB.
  • RDS instances with standard SSDs: up to 6,000 GB.
  • RDS instances with enhanced SSDs (ESSDs): up to 32,000 GB.
The storage capacity of an RDS instance that is equipped with local SSDs varies based on the instance type. This limit does not apply to RDS instances that are equipped with standard SSDs or ESSDs. For more information, see Primary ApsaraDB RDS instance types.
Number of connections Up to 76,800. The number of connections that can be established to an RDS instance varies based on the instance type. For more information, see Primary ApsaraDB RDS instance types.
IOPS None.

Quotas

Quota Description
Read-only instances

Read-only instances are supported only for RDS instances that run PostgreSQL 10.0 or later. The read-only instances that you create must reside in the same region as the primary RDS instance to which these read-only instances are attached.

  • If the primary RDS instance is equipped with local SSDs:
    • You can create up to five read-only instances.
    • You can create read-only instances only when the primary RDS instance is a dedicated instance that provides at least 8 cores and 32 GB of memory.
  • If the primary RDS instance is equipped with standard SSDs or ESSDs:
    • You can create up to 32 read-only instances.
    • Each read-only RDS instance runs in a single-node architecture. In this architecture, no secondary RDS instance is provided as a standby for the read-only RDS instance.

For more information about read-only instances, see Overview of read-only ApsaraDB RDS for PostgreSQL instances.

Tag The key of a tag must be unique. You can add a maximum of 20 tags to an RDS instance. You can add tags to a maximum of 50 RDS instances at a time. For more information, see Add tags to ApsaraDB RDS for MySQL instances.
Free quota for backup storage

RDS instances that are equipped with standard SSDS or ESSDs support only snapshot backups. RDS instances that are equipped with local SSDs support only physical backups. If your backup usage exceeds the free quota, you are charged additional fees. You can calculate your excess backup storage by using the following formula: Excess backup storage usage = Size of data backup files + Size of log backup files - Free quota. Unit: GB. The result can only be rounded up to the next integer.

  • RDS instances with local SSDs: Free quota for the storage of physical backup files = 50% × Purchased storage capacity.
  • RDS instances with standard SSDs or ESSDs: Free quota for the storage of snapshot backup files = 200% × Purchased storage capacity.

For more information, see Back up an ApsaraDB RDS for PostgreSQL instance.

Backup retention period The default backup retention period is 7 days, and the maximum backup retention period is 730 days.
Error log retention period The error log retention period is 30 days. For more information, see View logs.
Retention period of slow log details The retention period of slow log details is 30 days. For more information, see View logs.

Limits about names

Item Description
Instance name
  • The name of an RDS instance must be 2 to 256 characters in length.
  • The name of an RDS instance can contain letters, digits, underscores (_), and hyphens (-).
  • The name of an RDS instance must start with a letter.
Username
  • The username of an account must be 2 to 16 characters in length for RDS instances that are equipped with local SSDs and must be 2 to 63 characters for RDS instances that are equipped with standard SSDs or ESSDs.
  • The username of an account can contain lowercase letters, digits, and underscores (_).
  • The username of an account must start with a lowercase letter and end with a lowercase letter or a digit.
  • The username of an account must be unique.
  • The username of an account cannot contain SQL keywords. For more information, see SQL keywords.
Database name
  • The name of a database can contain up to 63 characters in length.
  • The name of a database can contain lowercase letters, digits, underscores (_), and hyphens (-).
  • The name of a database must start with a lowercase letter and end with a lowercase letter or digit.
  • The name of a database must be unique.
  • The name of a database cannot contain SQL keywords. For more information, see SQL keywords.

Limits about security

Item Description
Password
The password of an account must meet the following requirements:
  • The password must be 8 to 32 characters in length.
  • The password must contain at least three of the following character types: uppercase letters, lowercase letters, digits, and special characters. The password can contain any of the following characters: ! @ # $ % ^ & * ( ) _ + - =.
Port By default, an RDS instance is connected over port 5432. You can change the port number based on your business requirements.
Instance parameters For security and stability reasons, some parameters cannot be reconfigured. You can reconfigure most of the instance parameters in the ApsaraDB RDS console or by using the ApsaraDB RDS API. For more information, see Manage the parameters of an ApsaraDB RDS for PostgreSQL instance.
Disk encryption You can enable disk encryption for an RDS instance only when you purchase the instance. Disk encryption cannot be disabled after it is enabled. For more information, see Configure disk encryption for an ApsaraDB RDS for PostgreSQL instance.
Number of security groups
You can configure up to 10 security groups to an RDS instance.
  • After you configure security groups for an RDS instance, the Elastic Compute Service (ECS) instances in the configured security groups can communicate with the RDS instance.
  • The security groups that you configured for an RDS instance must have the same network type as the RDS instance. This means that the network types of the RDS instance and the security groups that you want to configure must both be Virtual Private Cloud (VPC) or classic network.

For more information, see Configure a security group for an ApsaraDB RDS for PostgreSQL instance.

Number of IP address whitelists You can configure up to 50 IP address whitelists for an RDS instance. For more information, see Configure an IP address whitelist for an ApsaraDB RDS for PostgreSQL instance.
Root account You cannot create root accounts. ApsaraDB RDS for PostgreSQL does not provide superuser accounts such as root accounts.
Privileged account You can create and manage privileged accounts in the ApsaraDB RDS console or by using the ApsaraDB RDS API. A privileged account has permissions to disconnect all the standard accounts of the RDS instance on which the privileged account is created.
  • RDS instances with local SSDs: Only one privileged account can be created for each RDS instance.
  • RDS instances with standard SSDs or ESSDs: Multiple privileged accounts can be created for each RDS instance.

For more information, see Create an account on an ApsaraDB RDS for PostgreSQL instance.

Standard account You can create and manage standard accounts in the ApsaraDB RDS console, by using the ApsaraDB RDS API, or by executing SQL statements. You must manually grant the permissions on specific databases to each standard account. A standard account does not have permissions to create, manage, or disconnect the other accounts of the RDS instance on which the standard account is created.
  • RDS instances with local SSDs: Standard accounts are not supported.
  • RDS instances with standard SSDs or ESSDs: Multiple standard accounts can be created for each RDS instance.

For more information, see Create an account on an ApsaraDB RDS for PostgreSQL instance.

Limits on SQL commands

The limits on SQL commands in ApsaraDB RDS for PostgreSQL are the same as the limits on SQL commands in open source PostgreSQL. For more information, see SQL Commands and PostgreSQL Limits.

Other limits

Item Description
Public endpoint You must manually apply for a public endpoint. For more information, see View and change the internal and public endpoints and port numbers of an ApsaraDB RDS for PostgreSQL instance.
Replication ApsaraDB RDS for PostgreSQL provides a primary/secondary replication architecture in all RDS editions except the Basic Edition. In this architecture, a secondary RDS instance is provided as a standby for the primary RDS instance. Secondary RDS instances are invisible to you and cannot be accessed by your applications.
Instance restart You can restart an RDS instance only in the ApsaraDB RDS console or by using the ApsaraDB RDS API.
Tablespace creation You cannot create a tablespace.