What Is the Maximum Number of Connections to an RDS DB Instance?

RDS does not have constraints on the number of connections. This number is determined by the default value and value range of the DB engine. For example, you can set max_connections and max_user_connections in a parameter template to configure the maximum number of connections for an RDS MySQL DB instance.

About max_connections

The max_connections is closely related to storage space (unit: GB) of the DB instance.

Estimated max_connections = Available node memory/Estimated memory occupied by a single connection

• Available node memory = Total memory – Memory occupied by the buffer pool – 1 GB (mysqld process/OS/monitoring program)
• Estimated memory usage of a single connection (single_thread_memory) = thread_stack (256 KB) + binlog_cache_size (32 KB) + join_buffer_size (256 KB) + sort_buffer_size (256 KB) + read_buffer_size (128 KB) + read_rnd_buffer_size (256 KB) ≈ 1 MB

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