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- What's New
- Function Overview
- Service Overview
-
Getting Started
- Overview
- Getting Started with Clusters
- Getting Started with Replica Sets
- Getting Started with Single Nodes
- Logging In to the DDS Console
- Example: Buying and Connecting to a DDS Instance
- Change History (Getting Started) Europe Site
-
User Guide
- Migrating Data
- Performance Tuning
- Permissions Management
- Instance Lifecycle Management
- Instance Modifications
- Data Backups
- Data Restorations
-
Parameter Template Management
- Overview
- Creating a Parameter Template
- Modifying a Parameter Template
- 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
- Billing
- Tags
- Quotas
- DDS Usage Suggestions
- Change History
- Developer Guide
-
Best Practices
- Overview
- Common Methods for Connecting to a DDS Instance
- 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 Mongos Cache Problem?
- How Do I Solve the High CPU Usage Issue?
- Creating a User and Granting the Read-Only Permission to the User
- 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
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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
- Adding Nodes to a Replica Set Instance
- Adding a Read Replica to an Instance
- 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
- Parameter Configuration
- Log Information Queries
- Tag Management
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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
- Quota Management
- Task Management
- API V3 (Unavailable Soon)
- Examples
- Permissions Policies and Supported Actions
- Appendix
- Change History (European Sites)
- SDK Reference
-
FAQs
-
Product Consulting
- What Is the Relationship Between DDS and MongoDB Community Edition?
- What Are the Differences Between DDS and GaussDB(for 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 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
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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
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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?
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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
- Change History (FAQs) Europe Site
-
Product Consulting
-
Troubleshooting
- 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 (Troubleshooting) European Sites
- Videos
Show all
Parameters
Database parameters are key configuration items in a database system. Improper parameter settings may adversely affect database performance. This document describes some important parameters. For details on parameter descriptions, visit MongoDB official website.
For details about how to change parameter values on the console, see Modifying a Parameter Template.
- enableMajorityReadConcern
This parameter indicates whether data read has been acknowledged by a majority of nodes.
The default value is false, indicating that data read is returned after being acknowledged by a single node.
If this parameter is set to true, data read is returned after being acknowledged by a majority of nodes. This operation will increase the size of the LAS file, resulting in high CPU usage and disk usage.
In DDS, read concern cannot be set to majority. If majority read concern is required, you can set write concern to majority, indicating that data is written to a majority of nodes. In this way, data on most nodes is consistent. Then, by reading data from a single node, it can be ensured that the data has been written to a majority of nodes, and there are no dirty reads.
NOTE:
Write concern and read concern respectively specify the write and read policies for MongoDB.
If read concern is set to majority, data read by users has been written to a majority of nodes and will not be rolled back to avoid dirty reads.
- failIndexKeyTooLong
The default value is true.
This parameter cannot be modified to avoid an excessively long index key.
- net.maxIncomingConnections
This parameter indicates the maximum number of concurrent connections that mongos or mongod can accept. The default value depends on the instance specifications. This parameter is displayed as default before being set, indicating that the parameter value varies with the memory specifications.
- security.javascriptEnabled
The default value is false.
This parameter indicates whether JavaScript scripts can be executed on mongod. For security purposes, the default value is false, indicating that JavaScript scripts cannot be executed on mongod, and the mapreduce and group commands cannot be used.
- disableJavaScriptJIT
The default value is true.
This parameter indicates whether to disable JavaScript JIT compilation. JavaScript JIT compilation enables just-in-time (JIT) compilation to improve the performance of running scripts.
disableJavaScriptJIT: The default value is true, indicating that the JavaScriptJIT compiler is disabled. To enable JavaScript JIT compilation, set disableJavaScriptJIT to false.
- operationProfiling.mode
The parameter value is slowOp by default.
This parameter indicates the level of the database analyzer.
This parameter supports the following values:
- The default value is slowOp, indicating that the collector records statements whose response time exceeds the threshold.
- The value off indicates that the analyzer is disabled and does not collect any data.
- The value all indicates that the collector collects data of all operations.
- operationProfiling.slowOpThresholdMs
The default value is 500 and the unit is ms.
This parameter indicates the threshold for slow queries in the unit of ms. Queries that take longer than the threshold are deemed as slow queries.
Unless otherwise specified, setting the value to 500 ms is recommended.
- maxTransactionLockRequestTimeoutMillis
The value ranges from 5 to 100, in milliseconds. The default value is 5.
This parameter specifies the time for a transaction to wait for locks. If the time is exceeded, the transaction is rolled back.
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