- What's New
- Function Overview
- Product Bulletin
- Service Overview
- Billing
-
Getting Started
- Getting Started with RDS for MySQL
- Getting Started with RDS for MariaDB
- Getting Started with RDS for PostgreSQL
- Change History
- Huawei Cloud MySQL Kernel
-
User Guide
-
Working with RDS for MySQL
- Suggestions on Using RDS for MySQL
- Database Migration
- Performance Tuning
- Instance Lifecycle
-
Instance Modifications
- Upgrading a Minor Version
- Changing a DB Instance Name
- Changing a DB Instance Description
- Changing the Replication Mode
- Changing the Failover Priority
- Changing a DB Instance Class
- Scaling Up Storage Space
- Configuring Storage Autoscaling
- Changing the Maintenance Window
- Changing a DB Instance Type from Single to Primary/Standby
- Promoting a Read Replica to Primary
- Manually Switching Between Primary and Standby DB Instances
- Changing the AZ of a Standby DB Instance
- Read Replicas
- Data Backups
- Data Restorations
-
Parameter Templates
- Creating a Parameter Template
- Modifying Parameters of an RDS for MySQL Instance
- Exporting a Parameter Template
- Comparing Parameter Templates
- Viewing Parameter Change History
- Replicating a Parameter Template
- Resetting a Parameter Template
- Applying a Parameter Template
- Viewing Application Records of a Parameter Template
- Modifying a Parameter Template Description
- Deleting a Parameter Template
- Connection Management
-
Database Proxy (Read/Write Splitting)
- Introducing Read/Write Splitting
- Suggestions on Using Database Proxy
- Kernel Versions
- Best Practices for Database Proxy
- Enabling Read/Write Splitting
- Configuring Transaction Splitting
- Configuring Connection Pools
- Configuring Multi-Statement Processing Modes
- Changing a Proxy from Pay-per-Use to Yearly/Monthly
- Configuring the Delay Threshold and Routing Policy
- Changing the Read/Write Splitting Address
- Changing the Read/Write Splitting Port
- Changing the Instance Class of a DB Proxy Instance
- Changing the Number of Proxy Nodes
- Upgrading the Kernel Version of Database Proxy
- Enabling or Disabling Access Control
- Restarting a Database Proxy
- Modifying Read/Write Splitting Parameters
- Disabling Read/Write Splitting
- Testing Read/Write Splitting Performance
- Database Management
- Account Management (Non-Administrator)
- Account and Network Security
- Metrics
- Interconnection with CTS
- Log Management
- Task Center
- Billing Management
- Managing Tags
-
Working with RDS for MariaDB
- Suggestions on Using RDS for MariaDB
- Instance Connection
- Parameter Tuning
- Instance Lifecycle
- Instance Modifications
- Read Replicas
- Data Backups
- Data Restorations
-
Parameter Templates
- Creating a Parameter Template
- Modifying RDS for MariaDB Instance Parameters
- Exporting a Parameter Template
- Importing a Parameter Template
- Comparing Parameter Templates
- Viewing Parameter Change History
- Replicating a Parameter Template
- Resetting a Parameter Template
- Applying a Parameter Template
- Viewing Application Records of a Parameter Template
- Modifying a Parameter Template Description
- Deleting a Parameter Template
- Connection Management
- Database Management
- Account Management (Non-Administrator)
- Account and Network Security
- Metrics
- Interconnection with CTS
- Log Management
- Task Center
- Managing Tags
-
Working with RDS for PostgreSQL
- Suggestions on Using RDS for PostgreSQL
- Database Migration
- Performance Tuning
- Instance Lifecycle
-
Instance Modifications
- Upgrading a Minor Version
- Changing a DB Instance Name
- Changing a DB Instance Description
- Changing the Replication Mode
- Changing the Failover Priority
- Changing a DB Instance Class
- Scaling Storage Space
- Changing the Maintenance Window
- Changing a DB Instance Type from Single to Primary/Standby
- Manually Switching Between Primary and Standby DB Instances
- Changing the AZ of a Standby DB Instance
- Read Replicas
- Data Backups
- Data Restorations
-
Parameter Templates
- Creating a Parameter Template
- Modifying Parameters of an RDS for PostgreSQL Instance
- Exporting a Parameter Template
- Comparing Parameter Templates
- Viewing Parameter Change History
- Replicating a Parameter Template
- Resetting a Parameter Template
- Applying a Parameter Template
- Viewing Application Records of a Parameter Template
- Modifying a Parameter Template Description
- Deleting a Parameter Template
- Connection Management
- Extension Management
- Tablespace Management
- Account and Network Security
- Metrics
- Interconnection with CTS
- Log Management
- Task Center
- Billing Management
- Major Version Upgrade
- Managing Tags
-
Working with RDS for MySQL
- Best Practices
- Performance White Paper
-
API Reference
- Before You Start
- API Overview
- Calling APIs
- API v3.1 (Recommended)
-
API v3 (Recommended)
- Querying Version Information About APIs
- Querying Version Information About a DB Engine
- Querying Database Specifications
- Querying the Storage Type of a Database
-
DB Instance Management
- Creating a DB Instance
- Stopping an Instance
- Changing a DB Instance Name
- Changing the Description of a DB Instance
- Changing DB Instance Specifications
- Scaling Up Storage Space of a DB Instance
- Changing a Single DB Instance to Primary/Standby DB Instances
- Rebooting a DB Instance
- Deleting a DB Instance
- Querying DB Instances
- Binding and Unbinding an EIP
- Changing the Failover Priority
- Manually Switching Primary/Standby DB Instances
- Changing the Data Replication Mode of Primary/Standby DB Instances
- Configuring the Maintenance Window
- Database Security
- Backup and Restoration
- Log Information Queries
-
Database and Account Management (MySQL)
- Creating a Database
- Querying Details About a Database
- Querying Databases
- Querying Authorized Databases of a Specified User
- Deleting a Database
- Creating a Database Account
- Querying Database Users
- Querying Authorized Users of a Specified Database
- Deleting a Database Account
- Configuring a Password for a Database Account
- Authorizing a Database Account
- Revoking Permissions of a Database Account
- Resetting the Password for User root
- Database and Account Management (PostgreSQL)
-
Parameter Management
- Obtaining a Parameter Template List
- Creating a Parameter Template
- Modifying a Parameter Template
- Applying a Parameter Template
- Modifying Parameters of a Specified DB Instance
- Obtaining the Parameter Template of a Specified DB Instance
- Obtaining Parameters in a Specified Parameter Template
- Deleting a Parameter Template
- Recycling a DB Instance
- Tag Management
- Obtaining Task Information
- Appendix
- Change History
- SDK Reference
-
FAQs
- Product Consulting
- Resource and Disk Management
-
Database Connection
- What Should I Do If I Can't Connect to My RDS DB Instance?
- Can an External Server Access the RDS Database?
- What Do I Do If the Number of RDS Database Connections Reaches the Upper Limit?
- What Is the Maximum Number of Connections to an RDS DB Instance?
- How Can I Create and Connect to an ECS?
- What Should I Do If an ECS Cannot Connect to an RDS DB Instance Through a Private Network?
- What Should I Do If a Database Client Problem Causes a Connection Failure?
- What Should I Do If an RDS Database Problem Causes a Connection Failure?
- How Do My Applications Access an RDS DB Instance in a VPC?
- Do Applications Need to Support Reconnecting to the RDS DB Instance Automatically?
- Why Cannot I Ping My EIP After It Is Bound to a DB Instance?
- How Can I Obtain the IP Address of an Application?
- Can I Access an RDS DB Instance Over an Intranet Connection Across Regions?
- Is an SSL Connection to a DB Instance Interrupted After a Primary/Standby Switchover or Failover?
- Database Migration
- Database Permission
- Database Storage
- Client Installation
- Backup and Restoration
- Database Monitoring
- Capacity Expansion and Specification Change
- Database Parameter Modification
- Network Security
- Change History
- Troubleshooting
- Videos
What Is the Maximum Number of Connections to an RDS DB Instance?
RDS does not have constraints on how many connections are supported. It depends on the default values and value ranges of the following parameters: max_connections and max_user_connections for the MySQL DB engine and max_connections for the PostgreSQL DB engine. You can customize these parameters in a parameter template.
Definition
The maximum number of connections refers to the concurrent connections allowed for a DB instance.
How to Change It
Setting the Maximum Number of Connections to an Appropriate Value
- RDS for MySQL
- In addition to the value of max_connections, the maximum number of concurrent client connections allowed by RDS for MySQL is also limited by the maximum number of files that can be opened by a single process in the operating system. For example, if the maximum number of files that can be opened by each process is set to 100 in the operating system, the max_connections parameter does not take effect even if it is set to 200.
- Check the maximum number of files that can be opened by a single process in the operating system. The default value is 1024.
ulimit -n
- Check the value of open_files_limit. open_files_limit indicates the maximum number of files that can be opened by a single process, which is read from the operating system during RDS for MySQL startup.
show variables like 'open_files_limit';
- Suggestions
The maximum number of RDS for MySQL connections can be modified to any amount allowed by your instance specifications. The maximum number of connections supported is closely related to the instance memory.
max_connections: maximum number of concurrent connections to a DB instance. If this parameter is set to default, the maximum number of connections depends on the memory (unit: GB) of the DB instance. The formula is as follows:
Estimated value of max_connections = Available node memory/Estimated memory occupied by a single connection
NOTE:
- 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.
Table 1 Max_connections for different memory specifications Memory (GB)
Connections
512
100,000
256
60,000
128
30,000
64
18,000
32
10,000
Set the maximum number of connections to an appropriate value because more connections consume more system resources.
- RDS for PostgreSQL
Set max_connections based on the complexity of your workloads.
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