- What's New
- Function Overview
-
Product Bulletin
- Vulnerability Notice
-
Product Notices
- [Notice] Starting OBT for DDS Cluster 5.0 on Nov 5, 2024
- [Notice] Huawei Cloud DDS Replica Set 5.0 Will Be Released Commercially on Oct 11, 2024
- [Notice] Huawei Cloud DDS 3.4 Will Be Discontinued on Oct 11, 2024
- [Notice] Starting OBT for DDS 5.0 on July 24, 2024
- [Notice] Specifications with CPU-Memory Ratio of 1:8 Will Be Available for x86-Powered Enhanced II Replica Set Instances and Cluster Shards on February 15, 2023
- [Notice] DDS 4.4 OBT Invitation
- [Product Discontinuation Notice] Huawei Cloud Document Database Service (DDS) Single Node Instances Will Be Discontinued on July 15, 2023
- [Notice] Huawei Cloud DDS 4.4 Will Be Released Commercially on Oct 08, 2023
- Version Description
- Product Release Notes
-
Service Overview
- Infographics
- What Is DDS?
- Advantages
- Comparison Between DDS and On-Premises Databases
- Typical Application Scenarios
- Functions and Features
- System Architecture
- Instances
- Notes and Constraints
- Basic Concepts
- Compatibility
- Security
- Permissions
- Related Services
- Mapping Between DDS Versions and Community Versions
- Billing
- Getting Started
-
User Guide
- Buying an Instance
-
Connecting to a DB Instance
- Connecting to a Cluster Instance
- Connecting to a Replica Set Instance
- Connecting to a Single Node Instance
- Data Migration
- Performance Tuning
- Permissions Management
- Instance Lifecycle Management
-
Instance Modifications
- Changing an Instance Name
- Changing an Instance Description
- Modifying an Instance Tag
- Changing the Name of the Replica Set in the Connection Address
- Upgrading a Minor Engine Version
- Upgrading a Major Engine Version
- Scaling Up Storage Space
- Changing an Instance Class
- Changing Cluster Instance Nodes
- Changing Replica Set Instance Nodes
- Configuring the Maintenance Window
- Changing an AZ
- Updating the OS of a DB Instance
-
Data Backups
- Backup Principles and Solutions
- Configuring an Automated Backup Policy
- Configuring an Incremental Backup Policy
- Configuring the Cross-Region Backup Policy
- Setting Backup Method for a DB Instance
- Creating a Manual Backup
- Deleting a Manual Backup
- Deleting an Automated Backup
- Stopping a Backup
- Downloading a Backup File
-
Data Restorations
- Solutions
- Restoring Data to a New Instance
- Restoring Data to the Original Instance
- Restoring Data to a Point in Time
- Restoring Data to an On-Premises Database
- Restoring Data of Enhanced Edition
-
Parameter Template Management
- Overview
- Creating a Parameter Template
- Modifying DDS DB Instance Parameters
- Viewing Parameter Change History
- Exporting a Parameter Template
- Comparing Parameter Templates
- Replicating a Parameter Template
- Resetting a Parameter Template
- Applying a Parameter Template
- Viewing Application Records of a Parameter Template
- Modifying the Description of a Parameter Template
- Deleting a Parameter Template
- Connection Management
- Database Usage
- Data Security
- Monitoring and Alarm Reporting
- Auditing
- Logs
- Task Center
- DBA Assistant
- SQL Execution Control
- Cross-AZ Disaster Recovery
- Tags
- Quotas
- DDS Usage Suggestions
- Developer Guide
-
Best Practices
- Overview
- Security Best Practices
- Common Methods for Connecting to a DDS Instance
- From Other Cloud MongoDB to DDS
- From On-Premises MongoDB to DDS
- From ECS-hosted MongoDB to DDS
- How Do Replica Sets Achieve High Availability and Read/Write Splitting?
- Sharding
- How Do I Improve DDS Performance by Optimizing SQL Statements?
- How Do I Prevent the dds mongos Cache Problem?
- How Do I Solve the High CPU Usage Issue?
- How Do I Troubleshoot High Memory Usage of DDS DB Instances?
- What Can I Do If the Number of Connections of an Instance Reaches Its Maximum?
- Creating a User and Granting the Read-Only Permission to the User
- Proper Use of Data Definition Languages (DDL) Statements
- How Is a DDS Node Going to Be Disconnected and What Can I Do?
- Security White Paper
- Performance White Paper
-
API Reference
- Before You Start
- API Overview
- Calling APIs
- Getting Started
-
APIs V3.0 (Recommended)
- Querying the API Version
- Querying Database Version Information
- Querying Database Specifications
- Querying the Database Disk Type
-
DB Instance Management
- Creating a DB Instance
- Restarting a DB Instance
- Deleting a DB Instance
- Querying Instances and Details
- Scaling Up Storage Space
- Adding Nodes for a Cluster Instance
- Modifying DB Instance Specifications
- Performing a Primary/Secondary Switchover in a Replica Set Instance
- Enabling or Disabling SSL
- Modifying a DB Instance Name
- Changing an Instance Description
- Changing a Database Port
- Changing a Security Group
- Binding an EIP
- Unbinding an EIP
- Changing a Private IP Address
- Creating Shard or Config IP Addresses of a Cluster Instance
- Configuring Cross-CIDR Access for a Replica Set
- Querying AZs to Which an Instance Can Be Migrated
- Migrating a DB Instance to Another AZ
- Setting the Recycle Bin Policy
- Adding Nodes to a Replica Set Instance
- Adding a Read Replica to an Instance
- Upgrading the Database Patch
- Enabling or Disabling Monitoring by Seconds
- Querying Second-Level Monitoring Configurations
- Configuring the Maintenance Window
- Querying the Recycling Policy of a DB Instance
- Querying DB Instances in the Recycle Bin
- Checking for Weak Passwords
- Querying the Estimated Database Patch Upgrade Duration
- Querying Instance Disk Information
- Obtaining the SSL Certificate Download Address
- Querying the Name of the Replica Set in the Connection Address
- Changing the Name of the Replica Set in the Connection Address
- Deleting Instance Nodes
- Deleting a Read Replica of an Instance
- Querying Access Across CIDR Blocks for a Replica Set Instance
- Querying LTS Log Configurations
- Associating an Instance with an LTS Log Stream
- Disassociating an Instance from an LTS Log Stream
- Configuring an Autoscaling Policy for Storage Space
- Querying the Autoscaling Policy of Storage Space
- Upgrading the Minor Versions of DB Instances in Batches
- Connection Management
-
Backup and Restoration
- Creating a Manual Backup
- Deleting a Manual Backup
- Querying the Backup List
- Querying an Automated Backup Policy
- Setting an Automated Backup Policy
- Restoring Data to a New DB Instance
- Obtaining the Link for Downloading a Backup File
- Querying the Restoration Time Ranges
- Obtaining the List of Databases That Can Be Restored
- Obtaining the List of Database Collections That Can Be Restored
- Restoring Data to the Original DB Instance
- Restoring Databases and Tables to a Point in Time
- Stopping a Backup
- Deleting Manual Backups in Batches
-
Parameter Configuration
- Obtaining Parameter Templates
- Creating a Parameter Template
- Deleting a Parameter Template
- Obtaining Details About a Parameter Template
- Modifying a Parameter Template
- Applying a Parameter Template
- Obtaining Parameters of a Specified DB Instance
- Modifying Parameters of a Specified DB Instance
- Querying Available DB Instances
- Viewing Application Records of a Parameter Template
- Viewing Parameter Change History
- Comparing Parameter Templates
- Replicating a Parameter Template
- Resetting a Parameter Template
- Checking Whether a Parameter Template Name Is Unique
- Viewing Parameter Change History of an Instance
-
Log Information Queries
- Querying Database Slow Logs (New)
- Obtaining Links for Downloading Slow Query Logs
- Showing Original Slow Logs
- Querying Database Error Logs (New)
- Obtaining Links for Downloading Error Logs
- Configuring SQL Audit
- Querying SQL Audit Policy
- Obtaining the Audit Log List
- Obtaining Links for Downloading Audit Logs
- Querying the Switch of Show Original Log
- Deleting Audit Logs
- Tag Management
-
Managing Databases and Users
- Creating a Database User
- Creating a Database Role
- Querying Details About Database Users
- Querying the Database Role List
- Changing the Password of a Database User
- Checking the Password for Logging In to a Database
- Querying Cluster Balancing Settings
- Enabling or Disabling Cluster Balancing
- Setting the Activity Time Window for Cluster Balancing
- Deleting a Database User
- Deleting a Database Role
- Querying Databases
- Quota Management
- Database O&M
- Task Management
- API V3 (Unavailable Soon)
- Examples
- Permissions Policies and Supported Actions
- Appendix
- SDK Reference
-
FAQs
-
Product Consulting
- What Is the Relationship Between DDS and MongoDB Community Edition?
- Q&A About Switching Storage Engine to RocksDB for DDS 4.2 and Later Versions
- What Are the Differences Between DDS and GeminiDB Mongo?
- What Precautions Should Be Taken When Using DDS?
- What Is the Availability of DDS DB Instances?
- Will My DDS DB Instances Be Affected by Other Users' DDS DB Instances?
- Does DDS Support Multi-AZ Deployment?
- Can I Change the VPC for a Created Instance?
- Can I Change the Region for a Created Instance?
- What Is Hidden Node?
- Database Versions
- Resource Freezing, Release, Deletion, and Unsubscription
-
Resource and Disk Management
- Which Items Occupy the Storage Space of DDS Instances?
- Which Types of Logs and Files Occupy DDS DB Instance Storage Space?
- Why Is the Storage Space Usage Displayed on the GUI Smaller Than the Actual Usage?
- Why Does Available Disk Space Not Increase After Data Is Deleted?
- Why Is the Resident Memory of a 4 vCPUs/8 GB Memory Replica Set Instance Only 4 GB?
- Capacity Expansion and Specification Changes
-
Database Performance
- When Will a Primary/Standby Switchover Be Triggered for a Cluster or Replica Set?
- High Storage Usage
- What Is the Time Delay for Primary/Secondary Synchronization in a Replica Set?
- How Is Data Transferred Between the Primary and Secondary Nodes of a Replica Set?
- How Do I Clear an Alarm Saying the Shard Memory Usage Exceeds 90%?
- What Can I Do If a Query Error Is Reported After Data Is Written Into the DDS Cluster?
- Database Permissions
-
Creation and Deletion
- How Do I Select Instance Specifications and Nodes?
- Why Is an Instance Not Displayed on the Console After It Is Created?
- Can I Use a Template to Create DDS DB Instances?
- Why Is Data Missing from My Database?
- Will My Backups Be Deleted If I Delete My Cloud Account?
- What Are the Differences Between Instance Deletion and Unsubscription?
-
Database Connection
- What Should I Do If I Fail to Connect to a DDS Instance?
- What Can I Do If the Number of Connections of an Instance Reaches Its Maximum?
- How Do I Query and Limit the Number of Connections?
- What Should I Do If the ECS and DDS Are Deployed in Different VPCs and They Cannot Communicate with Each Other?
- Do Applications Need to Support Automatic Reconnecting to the DDS Database?
- How Do I Create and Log In to an ECS?
- Installing a Client
- Database Usage
- Database Migration
- Database Storage
- Database Parameters
- Backup and Restoration
- Network Security
- Monitoring and Alarm
-
Product Consulting
-
Troubleshooting
- Overview
- DDS Instance Node Fault Handling Mechanism
- Connection Failure Message: network error while attempting to run command 'isMaster'
- Connection Failure Messages: No route to host and connection attempt failed
- Connection Failure Message: Authentication failed
- Connection Failure Message: couldn't connect to server
- Connection Failure Message: cannot list multiple servers in URL without 'replicaSet' option
- Connection Failure Message: Timeout while receiving message
- Connection Failure Message: exception: login failed and U_STRINGPREP_PROHIBITED_ERROR
- Change History
- Videos
- Glossary
-
More Documents
-
User Guide (ME-Abu Dhabi Region)
- Introduction
- Logging In to the DDS Console
- Getting Started with Clusters
- Getting Started with Replica Sets
- Connection Management
- Migrating Data
- Account Management
-
Instance Management
- Changing a DB Instance Name
- Adding Cluster Instance Nodes
- Reverting Cluster Instance Nodes
- Scaling Up Storage Space
- Changing the CPU or Memory of a Cluster DB Instance
- Changing the CPU or Memory of a Replica Set DB Instance
- Manually Switching the Primary and Secondary Nodes of a Replica Set
- Exporting DB Instance Information
- Restarting a DB Instance or a Node
- Deleting a DB Instance
- Recycling a DB Instance
- Backup and Restore
- Parameter Group Settings
- Task Center
- Monitoring and Alarm Reporting
- Auditing
- Log Management
- Tag
-
FAQs
- Product Consulting
- Database Performance
- Creation and Deletion
-
Database Connection
- Can an External Server Access the DDS DB Instance?
- What Is the Number of DDS Database Connections?
- What Should I Do If an ECS Cannot Connect to a DDS DB Instance?
- What Should I Do If a Database Client Problem Causes a Connection Failure?
- What Should I Do If a DDS Server Problem Causes a Connection Failure?
- How Can My Applications Access a DDS DB Instance in a VPC?
- Do Applications Need to Support Automatic Reconnecting to the DDS Database?
- How Do I Create and Log In to an ECS?
- How Can I Install a MongoDB Client?
- How Do I Install Robo 3T?
- Database Usage
- Database Storage
- Database Parameter Modification
- Backup and Restoration
- Network Security
- Resource Monitoring
- Log Management
- Which Commands are Supported or Restricted by DDS?
- Change History
-
API Reference (ME-Abu Dhabi Region)
- Before You Start
- API Overview
- Calling APIs
- Getting Started
-
API Description
- Querying the API Version
- Querying Database Version Information
- Querying All DB Instance Specifications
-
DB Instance Management
- Creating a DB Instance
- Restarting a DB Instance
- Deleting a DB Instance
- Querying DB Instances
- Scaling Up Storage Space
- Adding Nodes for a Cluster Instance
- Modifying DB Instance Specifications
- Performing a Primary/Secondary Switchover in a Replica Set Instance
- Enabling or Disabling SSL
- Modifying a DB Instance Name
- Changing a Database Port
- Changing a Security Group
- Binding an EIP
- Unbinding an EIP
- Changing a Private IP Address
- Backup and Restoration
- Tag Management
- Permissions Policies and Supported Actions
- Appendix
- Change History
-
User Guide (Paris Region)
- Introduction
- Logging In to the DDS Console
- Getting Started with Clusters
- Getting Started with Replica Sets
- Connection Management
- Migrating Data
- Account Management
-
Instance Management
- Changing a DB Instance Name
- Adding Cluster Instance Nodes
- Reverting Cluster Instance Nodes
- Scaling Up Storage Space
- Changing the CPU or Memory of a Cluster DB Instance
- Changing the CPU or Memory of a Replica Set DB Instance
- Manually Switching the Primary and Secondary Nodes of a Replica Set
- Exporting DB Instance Information
- Restarting a DB Instance or a Node
- Deleting a DB Instance
- Backup and Restore
- Parameter Group Settings
- Task Center
- Monitoring and Alarm Reporting
- Auditing
- Log Management
- Tag
-
FAQs
- Product Consulting
- Database Performance
- Creation and Deletion
-
Database Connection
- Can an External Server Access the DDS DB Instance?
- What Is the Number of DDS Database Connections?
- What Should I Do If an ECS Cannot Connect to a DDS DB Instance?
- What Should I Do If a Database Client Problem Causes a Connection Failure?
- What Should I Do If a DDS Server Problem Causes a Connection Failure?
- How Can My Applications Access a DDS DB Instance in a VPC?
- Do Applications Need to Support Automatic Reconnecting to the DDS Database?
- How Do I Create and Log In to an ECS?
- How Can I Install a MongoDB Client?
- How Do I Install Robo 3T?
- Database Usage
- Database Storage
- Database Parameter Modification
- Backup and Restoration
- Network Security
- Log Management
- Which Commands are Supported or Restricted by DDS?
- Change History
-
API Reference (Paris Region)
- Before You Start
- API Overview
- Calling APIs
- Getting Started
-
API Description
- Querying the API Version
- Querying Database Version Information
- Querying All DB Instance Specifications
-
DB Instance Management
- Creating a DB Instance
- Restarting a DB Instance
- Deleting a DB Instance
- Querying DB Instances
- Scaling Up Storage Space
- Adding Nodes for a Cluster Instance
- Modifying DB Instance Specifications
- Performing a Primary/Secondary Switchover in a Replica Set Instance
- Enabling or Disabling SSL
- Modifying a DB Instance Name
- Changing a Database Port
- Changing a Security Group
- Binding an EIP
- Unbinding an EIP
- Changing a Private IP Address
- Backup and Restoration
- Appendix
- Change History
-
User Guide (Kuala Lumpur Region)
- Introduction
- Logging In to the DDS Console
- Getting Started with Clusters
- Getting Started with Replica Sets
- Connection Management
- Migrating Data
- Account Management
-
Instance Management
- Changing a DB Instance Name
- Adding Cluster Instance Nodes
- Reverting Cluster Instance Nodes
- Scaling Up Storage Space
- Changing the CPU or Memory of a Cluster DB Instance
- Changing the CPU or Memory of a Replica Set DB Instance
- Manually Switching the Primary and Secondary Nodes of a Replica Set
- Exporting DB Instance Information
- Restarting a DB Instance or a Node
- Deleting a DB Instance
- Recycling a DB Instance
- Backup and Restore
- Parameter Group Settings
- Task Center
- Monitoring and Alarm Reporting
- Auditing
- Log Management
- Tag
-
FAQs
- Product Consulting
- Database Performance
- Creation and Deletion
-
Database Connection
- Can an External Server Access the DDS DB Instance?
- What Is the Number of DDS Database Connections?
- What Should I Do If an ECS Cannot Connect to a DDS DB Instance?
- What Should I Do If a Database Client Problem Causes a Connection Failure?
- What Should I Do If a DDS Server Problem Causes a Connection Failure?
- How Can My Applications Access a DDS DB Instance in a VPC?
- Do Applications Need to Support Automatic Reconnecting to the DDS Database?
- How Do I Create and Log In to an ECS?
- How Can I Install a MongoDB Client?
- How Do I Install Robo 3T?
- Database Usage
- Database Storage
- Database Parameter Modification
- Backup and Restoration
- Network Security
- Resource Monitoring
- Log Management
- Which Commands are Supported or Restricted by DDS?
- Change History
-
API Reference (Kuala Lumpur Region)
- Before You Start
- API Overview
- Calling APIs
- Getting Started
-
API Description
- Querying the API Version
- Querying Database Version Information
- Querying All DB Instance Specifications
-
DB Instance Management
- Creating a DB Instance
- Restarting a DB Instance
- Deleting a DB Instance
- Querying DB Instances
- Scaling Up Storage Space
- Adding Nodes for a Cluster Instance
- Modifying DB Instance Specifications
- Performing a Primary/Secondary Switchover in a Replica Set Instance
- Enabling or Disabling SSL
- Changing the Administrator Password
- Modifying a DB Instance Name
- Changing a Database Port
- Changing a Security Group
- Binding an EIP
- Unbinding an EIP
- Changing a Private IP Address
- Backup and Restoration
- Tag Management
- Permissions Policies and Supported Actions
- Appendix
- Change History
-
User Guide (ME-Abu Dhabi Region)
- General Reference
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How Do Replica Sets Achieve High Availability and Read/Write Splitting?
DDS replica set instances can store multiple duplicates to ensure data high availability and support the automatic switch of private IP addresses to ensure service high availability. To enhance the read and write performance of your client for connecting to the instance, you can use your client to read different data copies. You need to connect to replica set instances using HA connection addresses. You can also configure read/write splitting. Otherwise, the high availability and high read performance of replica set instances cannot be guaranteed.
The primary node of a replica set instance is not fixed. If the instance settings are changed, or the primary node fails, or primary and secondary nodes are switched, a new primary node will be elected and the previous one becomes a secondary node. The following figure shows the process of a switchover.
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Connecting to a Replica Set Instance (HA)
A DDS replica set consists of the primary, secondary, and hidden nodes. The hidden node is invisible to users. Read/Write splitting and HA can be realized only when you connect to the IP addresses and ports of the primary and secondary nodes of the replica set at the same time (in HA mode).
The following describes how to use URL and Java to connect to an instance in HA mode.
Method 1: Using a URL
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Example: mongodb://rwuser:****@192.168.0.148:8635,192.168.0.96:8635/test?authSource=admin&replicaSet=replica
In the preceding URL, 192.168.0.148:8635 and 192.168.0.96:8635 are the IP addresses and ports of the primary and secondary nodes, respectively. If you use this address, the connection between your client and the instance can be ensured even when a primary/standby switchover occurs. In addition, using multiple IP addresses and port numbers can enhance the read and write performance of the entire database.
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Method 2: Using a Java Driver
Sample code:
MongoClientURI connectionString = new MongoClientURI("mongodb://rwuser:****@192.168.0.148:8635,192.168.0.96:8635/test?authSource=admin&replicaSet=replica"); MongoClient client = new MongoClient(connectionString); MongoDatabase database = client.getDatabase("test"); MongoCollection<Document> collection = database.getCollection("mycoll");
Parameter |
Description |
---|---|
rwuser:**** |
Username and password for starting authentication |
192.168.0.148:8635,192.168.0.96:8635 |
IP addresses and ports of the primary and secondary nodes in a replica set instance |
test |
Name of the database to be connected |
authSource=admin |
Database username for authentication |
replicaSet=replica |
Name of the replica set instance type |
(Not Recommended) Connecting to a Replica Set Instance
Using the Connection Address
mongodb://rwuser:****@192.168.0.148:8635/test?authSource=admin&replicaSet=replica
In the preceding URL, 192.168.0.148:8635 is the IP address and port number of the current primary node. If a switchover occurs or the primary node is changed, the client fails to connect to the replica set instance because the IP address and port of the newly elected primary node is unknown. As a result, the database service becomes unavailable. In addition, read and write operations can only be performed on a fixed primary node, so the read and write performance cannot be improved by adding nodes.
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Read/Write Splitting
The following HA connection address is used as an example to describe how to connect to a DDS replica set instance:
mongodb://rwuser:<password>@192.168.xx.xx:8635,192.168.xx.xx:8635/test?authSource=admin&replicaSet=replica&readPreference=secondaryPreferred
The database account is rwuser, and the database is admin.
After the DB instance is connected, read requests are preferentially sent to the secondary node to implement read/write splitting. If the relationship between the primary and secondary nodes changes, write operations are automatically switched to the new primary node to ensure high availability of DDS.
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