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Storage Engine and Version

Last updated: 2022-08-31 17:11:42

    This document describes the version and storage engine information of TencentDB for MongoDB to help you select appropriate options.

    Versions and Storage Engines

    TencentDB for MongoDB supports WiredTiger and Rocks storage engines.


    With a typical Btree structure, WiredTiger greatly outperforms MMAPv1, MongoDB's legacy storage engine. It provides concurrency control and compression mechanisms at different granularities, significantly reducing the storage costs. It offers the optimal performance and storage efficiency for different types of applications. WiredTiger is the default storage engine in MongoDB 3.2.


    Rocks organizes data based on the log-structured merge-tree (LSM tree) structure and specifically optimizes data write capabilities, which guarantee constantly efficient data writes and make it suitable for scenarios involving more writes but fewer reads. It is supported by MongoDB 3.2 only.

    Version Storage Engine
  • WiredTiger
  • Rocks
  • 3.6 WiredTiger
    4.0 WiredTiger
    4.2 WiredTiger

    Version Overview

    Feature Subfeature v3.2 v3.6 v4.0 v4.2
    Network Classic network SupportedSupportedSupportedSupported
    VPC SupportedSupportedSupportedSupported
    Security Group SupportedSupportedSupportedSupported
    Network change SupportedSupportedSupportedSupported
    Pay-as-You-Go SupportedSupportedSupportedSupported
    Pay-as-You-Go instance termination SupportedSupportedSupportedSupported
    Message subscription and notification SupportedSupportedSupportedSupported
    Elasticity Mongod configuration adjustment SupportedSupportedSupportedSupported
    Node quantity adjustment SupportedSupportedSupportedSupported
    Adjustment of node quantity per shard SupportedSupportedSupportedSupported
    Shard quantity adjustment Not supportedSupportedSupportedSupported
    Mongos access address Not supportedNot supportedSupportedSupported
    Mongos node quantity adjustment (sharded cluster) Not supportedNot supportedSupportedSupported
    Replica node promotion to primary node Not supportedSupportedSupportedSupported
    Oplog capacity adjustment Supported SupportedSupportedSupported
    Instance operations Instance list SupportedSupportedSupportedSupported
    Restart an instance SupportedSupportedSupportedSupported
    Batch instance restart SupportedSupportedSupportedSupported
    Instance termination SupportedSupportedSupportedSupported
    Switch to another project SupportedSupportedSupportedSupported
    Tag management SupportedSupportedSupportedSupported
    Password resetting SupportedSupportedSupportedSupported
    Unauthorized access Not supportedSupportedSupportedSupported
    Version upgrade Not supportedSupportedSupportedNot supported
    Maintenance time modification SupportedSupportedSupportedSupported
    Read-only instance SupportedSupportedSupportedSupported
    Disaster recovery instance SupportedSupportedSupportedSupported
    Multi-AZ deployment SupportedSupportedSupportedSupported
    System monitoring Monitoring metric list SupportedSupportedSupportedSupported
    Data comparison SupportedSupportedSupportedSupported
    Alarm rule configuration SupportedSupportedSupportedSupported
    Monitoring data export SupportedSupportedSupportedSupported
    Multi-Instance comparison and monitoring SupportedSupportedSupportedSupported
    Backup and rollback Backup list SupportedSupportedSupportedSupported
    Manual backup SupportedSupportedSupportedSupported
    Automatic backup SupportedSupportedSupportedSupported
    Backup file download SupportedSupportedSupportedSupported
    Instance clone SupportedSupportedSupportedSupported
    Database table rollback (replica set) SupportedSupportedSupportedSupported
    Database table rollback (sharded cluster) Not supportedNot supportedNot supportedNot supported
    Automatic backup policy configuration SupportedSupportedSupportedSupported
    Database management Create an account SupportedSupportedSupportedSupported
    Account password change SupportedSupportedSupportedSupported
    Account permission configuration SupportedSupportedSupportedSupported
    Slow log query SupportedSupportedSupportedSupported
    Slow log request management SupportedSupportedSupportedSupported
    Slow log download SupportedSupportedSupportedSupported
    Connection management SupportedSupportedSupportedSupported
    Task management List data loading SupportedSupportedSupportedSupported
    Filter by time SupportedSupportedSupportedSupported
    Filter by instance name SupportedSupportedSupportedSupported
    Task details display SupportedSupportedSupportedSupported
    Database audit Instance audit Not supportedNot supportedSupportedSupported
    Audit log Not supportedNot supportedSupportedSupported
    Recycle bin Instance list in recycle bin SupportedSupportedSupportedSupported
    Instance restoration SupportedSupportedSupportedSupported
    Batch instance restoration SupportedSupportedSupportedSupported
    Instance elimination SupportedSupportedSupportedSupported
    Migration Migration over public network SupportedSupportedSupportedSupported
    Self-Build on CVM SupportedSupportedSupportedSupported
    Migration over Direct Connect SupportedSupportedSupportedSupported
    Migration over VPN SupportedSupportedSupportedSupported
    TencentDB migration SupportedSupportedSupportedSupported
    Migration over CCN SupportedSupportedSupportedSupported
    Performance optimization Exception diagnosis SupportedSupportedSupportedSupported
    Performance trends monitoring SupportedSupportedSupportedSupported
    Slow query analysis SupportedSupportedSupportedSupported
    Space analysis SupportedSupportedSupportedSupported
    MongoStatus SupportedSupportedSupportedSupported
    MongoTop SupportedSupportedSupportedSupported
    Real-time session SupportedSupportedSupportedSupported
    Index recommendation SupportedSupportedSupportedSupported
    SQL throttling SupportedSupportedSupportedSupported

    Minor Version Description

    WiredTiger storage engine on v4.2

    Minor Version New Feature, Optimization, or Fix
  • Supported auditing database events with custom rules.
  • Supported accessing the database through SSL authentication.
  • WT.42.11.14 Improved the stability of moveChunk of the kernel.
    WT.42.11.13 Supported using commands to enable the enhanced changeStream mode.
  • Fixed the issue where an error was reported when creating and deleting a duplicate database repeatedly.
  • Fixed changeStream issues.
  • WT.42.11.11 Fixed the kernel exception during applyOps.
    WT.42.11.10 Optimized the database audit performance.
    WT.42.11.9 Supported database table rollback through physical backup to speed up backups.
    WT.42.11.8 Optimized the routing information refresh policy.
    WT.42.11.7 Optimized the control logic for adding shards.
    WT.42.11.6 Supported DDL operations for changeStream.
    WT.42.11.5 Optimized kernel parameters to improve the performance.
    WT.42.11.4 Blocked high-risk system operations.
    WT.42.11.3 Fixed the exception of the getMore operation.
    WT.42.11.2 Supported the maxTimeMS parameter.
    WT.42.11.1 Supported the online compact command.
    WT.42.11.0 Supported MongoDB 4.2.

    WiredTiger storage engine on v4.0

    Minor Version New Feature, Optimization, or Fix
  • Supported auditing database events with custom rules.
  • Supported accessing the database through SSL authentication.
  • WT.40.3.33
  • Supported speed limit for TTL indexing.
  • Supported setting the clearing window for expired TTL data.
  • WT.40.3.32
  • Improved the instance stability after database table rollback through physical backup.
  • Fixed memory leaks after connection failures.
  • WT.40.3.31 Supported SQL throttling.
    WT.40.3.30 Supported customizing the slow query threshold.
    WT.40.3.29 Optimized the database audit performance.
    WT.40.3.28 Optimized the routing information refresh policy for sharded clusters.
    WT.40.3.27 Supported database table rollback through physical backup.
    WT.40.3.26 Optimized the retry lock logic during write conflicts to improve the performance.
    WT.40.3.25 Optimized user permissions to avoid unauthorized operations.
    WT.40.3.24 Prohibited creating LSM engine tables and indexes.
    WT.40.3.23 Optimized the logic for adding shards.
    WT.40.3.22 Optimized the lock mechanism.
    WT.40.3.21 Optimized the changeStream logic.
    WT.40.3.20 Optimized the performance.
    WT.40.3.19 Optimized the session logic.
    WT.40.3.18 Optimized the replica database read performance.
    WT.40.3.17 Optimized the password-free access logic.
    WT.40.3.16 Optimized the monitoring data collection logic.
    WT.40.3.15 Supported database tables with millions of records.
    WT.40.3.14 Optimized the physical backup performance in case of many files.
    WT.40.3.13 Optimized the mongos connection mechanism.
    WT.40.3.12 Optimized the routing information refresh logic and audit performance.
    WT.40.3.11 Enhanced changeStream capabilities.
    WT.40.3.10 Supported the maxTimeMS parameter.
    WT.40.3.9 Supported mongos overload protection.
    WT.40.3.8 Supported database audit.
    WT.40.3.7 Optimized the session logic.
    WT.40.3.6 Improved the database connection performance and startup performance in case of many files.
    WT.40.3.5 Supported password-free access.
    WT.40.3.4 Fixed abnormal bloats of database disk files.
    WT.40.3.3 Supported IPv6.
  • Supported blocking writes to full disks.
  • Supported displaying the client connection information.
  • WT.40.3.1
  • Supported the superGeo command.
  • Supported physical backup.
  • Added new monitoring metrics.
  • WT.40.3.0 Released MongoDB 4.0 based on the WiredTiger engine.

    WiredTiger storage engine on v3.6

    Minor Version Description
  • Optimized the password-free access logic.
  • Optimized the display effect of the client list.
  • WT.36.8.11 Optimized the connection performance.
    WT.36.8.10 Optimized the logic of session and cross-node data sync.
    WT.36.8.9 Supported physical backup.
    WT.36.8.8 Supported password-free access.
    WT.36.8.7 Optimized the mongos connection pool mechanism.
    WT.36.8.6 Optimized the connection logic.
    WT.36.8.5 Supported IPv6.
    WT.36.8.4 Optimized the monitoring data collection logic.
    WT.36.8.3 Optimized the disk blocking logic.
    WT.36.8.2 Optimized the connection model.
    WT.36.8.1 Optimized the security mechanism.
    WT.36.8.0 Supported v3.6.

    WiredTiger storage engine on v3.2

    Minor Version Description
    WT.32.12.9 Supported setting the maximum timeout period of requests and creating indexes with the instance in the background by default.
    WT.32.12.8 Optimized the mongos connection pool mechanism.
    WT.32.12.7 Supported IPv6 and its parameter configuration.
    WT.32.12.6 Optimized kernel connection parameters to improve the performance.
    WT.32.12.5 Fixed issues such as occasional kernel exception.
    WT.32.12.4 Supported the superGeoNear command.
    WT.32.12.3 Optimized kernel parameters to improve the performance.
    WT.32.12.2 Supported adjusting the oplog capacity.
    WT.32.12.1 Supported dynamically adjusting the number of connections.
    WT.32.12.0 Supported the WiredTiger engine of MongoDB 3.2.

    Rocks storage engine on v3.2

    Minor Version Description
    ROCKS.32.12.3 Optimized connection parameters and performance.
    ROCKS.32.12.2 Optimized the replica database read performance.
    ROCKS.32.12.1 Supported read requests from replica databases and optimized snapshot expiration parameters.
    ROCKS.32.12.0 Supported the Rocks storage engine.
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