Help Center/ Relational Database Service_RDS for PostgreSQL/ FAQs/ Database Connection/ What Is the Maximum Number of Connections Allowed for an RDS for PostgreSQL Instance?
Updated on 2026-10-08 GMT+08:00
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What Is the Maximum Number of Connections Allowed for an RDS for PostgreSQL Instance?

RDS for PostgreSQL has no limit on how many connections each instance can have. The maximum number of connections is determined by the default values and value ranges of certain parameters in your DB engine.

What Is the Maximum Number of Connections?

The maximum number of connections refers to the concurrent connections allowed for a DB instance.

How to Change the Maximum Number of Connections

  • You can change the maximum number of connections allowed on the console. For details, see Modifying Instance Parameters.
  • To query the maximum number of connections allowed, run the following command: 
    show max_connections;

    If you want to change the maximum number of connections by running commands, submit a service ticket.

Setting the Maximum Number of Connections to an Appropriate Value

The max_connections parameter is closely related to the memory (GB) of the DB instance. The calculation formula is as follows:

Table 1 Calculation formula

Parameter

Formula

Version Involved

Unit

max_connections

min((total_mem_kb – shared_buffer) x 1,024.0/16 MB, 5,000)

All versions

Count

The following table lists the default values of max_connections for different memory specifications.

Table 2 Default values of max_connections for different memory specifications

Memory (GB)

Max. Client Connections (max_connections)

512

5,000

384

5,000

256

5,000

128

5,000

64

3,072

32

1,536

16

768

8

384

4

192

2

96
Parent Topic: Database Connection