- Release Notes and Announcements
- User Guide
- Product Introduction
- Purchase Guide
- Getting Started
- Operation Guide
- Access Management
- Instance Management
- Node Management
- Node Overview
- Viewing Node Information
- Adjusting Mongod Node Specification
- Adding Secondary Node
- Deleting Secondary Node
- Adding Read-Only Node
- Adjusting Shard Quantity
- Adjusting Mongos Node Specification
- Adding Mongos Node
- Enabling Mongos Access Address
- Promoting Secondary Node to Primary Node
- Restarting a Node
- Version Upgrade
- Network Configuration
- Monitoring
- Backup and Rollback
- Data Security
- SSL Authentication
- Database Management
- Multi-AZ Deployment
- Disaster Recovery/Read-Only Instances
- Recycle Bin
- Task Management
- Performance Optimization
- Data Migration Guide
- Creating a DTS Migration Task
- Migration Overview
- Supported Capabilities
- User Guide
- Migration Operation Guide
- Fix for Verification Failure
- MongoDB Connection Check
- Database/Table Content Conflict Check
- Source Database Node Role Check
- Oplog Check
- Source/Target Database Account Permission Check
- Database Version Check
- Database Capacity Check
- Target Database Load Check
- ShardKey Check
- Source Database Balancer Check
- Time Series Collection Verification
- Compression Algorithm Verification
- Consistency Check After Migration
- Creating MongoDB Data Subscription
- Creating a DTS Migration Task
- Practical Tutorial
- Optimizing Indexes to Break Through Read/Write Performance Bottlenecks
- Troubleshooting Mongos Load Imbalance in Sharded Cluster
- Considerations for Using Shard Clusters
- Sample of Reading and Writing Data in MongoDB Instance
- Methods for Importing and Exporting Data Based on CVM Connected with MongoDB
- What to Do for Errors of Repeated Instance Creation and Deletion of Databases with the Same Names?
- Troubleshooting MongoDB Connection Failures
- Performance Fine-Tuning
- Ops and Development Guide
- Troubleshooting
- API Documentation
- History
- API Category
- Making API Requests
- Backup APIs
- Introduction
- Instance APIs
- RenameInstance
- OfflineIsolatedDBInstance
- ModifyDBInstanceSpec
- IsolateDBInstance
- DescribeSpecInfo
- DescribeDBInstances
- DescribeClientConnections
- CreateDBInstanceHour
- AssignProject
- RenewDBInstances
- DescribeSlowLogs
- DescribeSlowLogPatterns
- InquirePriceRenewDBInstances
- InquirePriceModifyDBInstanceSpec
- InquirePriceCreateDBInstances
- DescribeDBInstanceDeal
- DescribeSecurityGroup
- DescribeInstanceParams
- ModifyDBInstanceSecurityGroup
- ModifyDBInstanceNetworkAddress
- Account APIs
- Task APIs
- Other APIs
- Data Types
- Error Codes
- Instance Connection
- Product Performance
- FAQs
- Service Agreement
- Glossary
- Contact Us
- Release Notes and Announcements
- User Guide
- Product Introduction
- Purchase Guide
- Getting Started
- Operation Guide
- Access Management
- Instance Management
- Node Management
- Node Overview
- Viewing Node Information
- Adjusting Mongod Node Specification
- Adding Secondary Node
- Deleting Secondary Node
- Adding Read-Only Node
- Adjusting Shard Quantity
- Adjusting Mongos Node Specification
- Adding Mongos Node
- Enabling Mongos Access Address
- Promoting Secondary Node to Primary Node
- Restarting a Node
- Version Upgrade
- Network Configuration
- Monitoring
- Backup and Rollback
- Data Security
- SSL Authentication
- Database Management
- Multi-AZ Deployment
- Disaster Recovery/Read-Only Instances
- Recycle Bin
- Task Management
- Performance Optimization
- Data Migration Guide
- Creating a DTS Migration Task
- Migration Overview
- Supported Capabilities
- User Guide
- Migration Operation Guide
- Fix for Verification Failure
- MongoDB Connection Check
- Database/Table Content Conflict Check
- Source Database Node Role Check
- Oplog Check
- Source/Target Database Account Permission Check
- Database Version Check
- Database Capacity Check
- Target Database Load Check
- ShardKey Check
- Source Database Balancer Check
- Time Series Collection Verification
- Compression Algorithm Verification
- Consistency Check After Migration
- Creating MongoDB Data Subscription
- Creating a DTS Migration Task
- Practical Tutorial
- Optimizing Indexes to Break Through Read/Write Performance Bottlenecks
- Troubleshooting Mongos Load Imbalance in Sharded Cluster
- Considerations for Using Shard Clusters
- Sample of Reading and Writing Data in MongoDB Instance
- Methods for Importing and Exporting Data Based on CVM Connected with MongoDB
- What to Do for Errors of Repeated Instance Creation and Deletion of Databases with the Same Names?
- Troubleshooting MongoDB Connection Failures
- Performance Fine-Tuning
- Ops and Development Guide
- Troubleshooting
- API Documentation
- History
- API Category
- Making API Requests
- Backup APIs
- Introduction
- Instance APIs
- RenameInstance
- OfflineIsolatedDBInstance
- ModifyDBInstanceSpec
- IsolateDBInstance
- DescribeSpecInfo
- DescribeDBInstances
- DescribeClientConnections
- CreateDBInstanceHour
- AssignProject
- RenewDBInstances
- DescribeSlowLogs
- DescribeSlowLogPatterns
- InquirePriceRenewDBInstances
- InquirePriceModifyDBInstanceSpec
- InquirePriceCreateDBInstances
- DescribeDBInstanceDeal
- DescribeSecurityGroup
- DescribeInstanceParams
- ModifyDBInstanceSecurityGroup
- ModifyDBInstanceNetworkAddress
- Account APIs
- Task APIs
- Other APIs
- Data Types
- Error Codes
- Instance Connection
- Product Performance
- FAQs
- Service Agreement
- Glossary
- Contact Us
Overview
When your business has a massive number of read requests, the primary and secondary database nodes may struggle to handle them, causing high latency, slow response, and severely dropped throughput. To solve this problem, TencentDB for MongoDB provides read-only nodes with an independent connection address, allowing data to be synced from a primary or secondary node with the lowest latency through oplog. You can create one or multiple read-only nodes to implement read/write separation and relieve the access pressure on the primary and secondary nodes.
Two or more nodes can implement load balancing for read requests and guarantee a high availability; that is, when a read-only node fails, the system will automatically switch it with a hidden node. If automatic switch isn't performed, you can switch the node on the Node Management tab, and the connection address to the node will remain unchanged. You can directly get the connection string in the Network section on the Instance Details page.
If a read-only node isn't in the candidate list of the primary node, it won't be elected as the primary node or participate in the election.
Version Description
TencentDB for MongoDB versions 4.0, 4.2, 4.4, 5.0 and 6.0 support adding read-only nodes, while v3.6 doesn't.
Directions
1. Log in to the TencentDB for MongoDB console.
2. In the MongoDB drop-down list on the left sidebar, select Replica Set Instance or Sharded Instance. The directions for replica set instances and sharded instances are similar.
3. Above the Instance List on the right, select the region.
4. In the instance list, find the target instance.
5. Click the Instance ID to enter the Instance Details page and click the Node Management tab.
6. On the Mongod Node tab, click Add Read-only Node.
Parameter | Description |
Instance Specification | Check the current specification of the instance, including the CPU core quantity, memory, disk capacity, total node quantity, and read-only node quantity to evaluate the number of read-only nodes to be added. |
Add Read-Only Node | The number of new read-only nodes. Value range: 0–5. |
AZ | The AZ where all read-only nodes are deployed. This parameter will be displayed if the instance nodes are in the same AZ. |
Compare | Compare the specifications before and after adding the read-only node to evaluate whether the new specification meets your needs. The specification of a replica set instance includes mongod specification, disk capacity, number of read-only nodes, and maximum number of connections. The specification of a sharded cluster instance includes number of shards, mongod specification, disk capacity, number of read-only nodes, and maximum number of connections. |
Total Fees | Pay-as-you-go: Hourly unit price after instance speciation adjustment. You can click Billing Details to view the billable items and billing formula and confirm the fees. |
7. Click OK.
8. On the left sidebar, select Task Management. In the task list, find the instance by ID or name and wait until the Task Status for adding the read-only node is marked as Completed.
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