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v3.0 (stable) dev v2.1
  • Introduction
  • Concepts
    • Architecture
    • Key Features
      • Horizontal Scalability
      • MySQL Compatible Syntax
      • Replicate from and to MySQL
      • Distributed Transactions with Strong Consistency
      • Cloud Native Architecture
      • Minimize ETL with HTAP
      • Fault Tolerance & Recovery with Raft
      • Automatic Rebalancing
      • Deployment and Orchestration with Ansible, Kubernetes, Docker
      • JSON Support
      • Spark Integration
      • Read Historical Data Without Restoring from Backup
      • Fast Import and Restore of Data
      • Hybrid of Column and Row Storage
      • SQL Plan Management
      • Open Source
      • Online Schema Changes
  • How-to
    • Get Started
      • Start a Local Cluster
        • From Binary
        • From Homebrew
        • From DBdeployer
        • In Kubernetes
        • In Docker Compose
      • Explore SQL with TiDB
      • Import Example Database
      • Read Historical Data
      • TiDB Binlog Tutorial
      • TiDB Data Migration Tutorial
      • TiSpark Quick Start Guide
    • Deploy
      • Hardware Recommendations
      • From Binary Tarball
        • For Testing Environments
        • For Production Environments
      • Orchestrated Deployment
        • Ansible Deployment (Recommended)
        • Ansible Offline Deployment
        • Docker Deployment
        • Kubernetes Deployment
      • Geographic Redundancy
        • Overview
        • Configure Location Awareness
      • Data Migration with Ansible
    • Configure
      • Time Zone
      • Memory Control
    • Secure
      • Transport Layer Security (TLS)
        • Enable TLS For MySQL Clients
        • Enable TLS Between TiDB Components
      • Generate Self-signed Certificates
    • Monitor
      • Overview
      • Monitor a TiDB Cluster
    • Migrate
      • Overview
      • Migrate from MySQL
        • Migrate the Full Data
        • Migrate the Incremental Data
      • Migrate from Aurora
      • Migrate from CSV
    • Maintain
      • Common Ansible Operations
      • Backup and Restore
      • Identify Slow Queries
    • Scale
      • Scale using Ansible
      • Scale a TiDB Cluster
    • Upgrade
      • Upgrade to TiDB 3.0
      • Upgrade to TiDB 2.1
      • Rolling updates with Ansible
      • Upgrade TiDB Data Migration
    • Troubleshoot
      • Troubleshoot Cluster Setup
      • Troubleshoot TiDB Data Migration
      • Troubleshoot TiDB Lightning
  • Reference
    • MySQL Compatibility
    • SQL
      • SQL Language Structure
        • Literal Values
        • Schema Object Names
        • Keywords and Reserved Words
        • User-Defined Variables
        • Expression Syntax
        • Comment Syntax
      • Data Types
        • Overview
        • Default Values
        • Numeric Types
          • `BIT`
          • `BOOL|BOOLEAN`
          • `TINYINT`
          • `SMALLINT`
          • `MEDIUMINT`
          • `INT|INTEGER`
          • `BIGINT`
          • `DECIMAL`
          • `FLOAT`
          • `DOUBLE`
        • Date and Time Types
          • `DATE`
          • `DATETIME`
          • `TIMESTAMP`
          • `TIME`
          • `YEAR`
        • String Types
          • `CHAR`
          • `VARCHAR`
          • `TEXT`
          • `LONGTEXT`
          • `BINARY`
          • `VARBINARY`
          • `TINYBLOB`
          • `BLOB`
          • `MEDIUMBLOB`
          • `LONGBLOB`
          • `ENUM`
          • `SET`
        • JSON Type
      • Functions and Operators
        • Function and Operator Reference
        • Type Conversion in Expression Evaluation
        • Operators
        • Control Flow Functions
        • String Functions
        • Numeric Functions and Operators
        • Date and Time Functions
        • Bit Functions and Operators
        • Cast Functions and Operators
        • Encryption and Compression Functions
        • Information Functions
        • JSON Functions
        • Aggregate (GROUP BY) Functions
        • Miscellaneous Functions
        • Precision Math
      • SQL Statements
        • `ADD COLUMN`
        • `ADD INDEX`
        • `ADMIN`
        • `ALTER TABLE`
        • `ALTER USER`
        • `ANALYZE TABLE`
        • `BEGIN`
        • `COMMIT`
        • `CREATE DATABASE`
        • `CREATE INDEX`
        • `CREATE TABLE LIKE`
        • `CREATE TABLE`
        • `CREATE USER`
        • `CREATE VIEW`
        • `DEALLOCATE`
        • `DELETE`
        • `DESC`
        • `DESCRIBE`
        • `DO`
        • `DROP COLUMN`
        • `DROP DATABASE`
        • `DROP INDEX`
        • `DROP TABLE`
        • `DROP USER`
        • `DROP VIEW`
        • `EXECUTE`
        • `EXPLAIN ANALYZE`
        • `EXPLAIN`
        • `FLUSH PRIVILEGES`
        • `FLUSH STATUS`
        • `FLUSH TABLES`
        • `GRANT <privileges>`
        • `INSERT`
        • `KILL [TIDB]`
        • `LOAD DATA`
        • `MODIFY COLUMN`
        • `PREPARE`
        • `RENAME INDEX`
        • `RENAME TABLE`
        • `REPLACE`
        • `REVOKE <privileges>`
        • `ROLLBACK`
        • `SELECT`
        • `SET [NAMES|CHARACTER SET]`
        • `SET PASSWORD`
        • `SET TRANSACTION`
        • `SET [GLOBAL|SESSION] <variable>`
        • `SHOW CHARACTER SET`
        • `SHOW COLLATION`
        • `SHOW [FULL] COLUMNS FROM`
        • `SHOW CREATE TABLE`
        • `SHOW CREATE USER`
        • `SHOW DATABASES`
        • `SHOW ENGINES`
        • `SHOW ERRORS`
        • `SHOW [FULL] FIELDS FROM`
        • `SHOW GRANTS`
        • `SHOW INDEXES [FROM|IN]`
        • `SHOW INDEX [FROM|IN]`
        • `SHOW KEYS [FROM|IN]`
        • `SHOW PRIVILEGES`
        • `SHOW [FULL] PROCESSSLIST`
        • `SHOW SCHEMAS`
        • `SHOW [FULL] TABLES`
        • `SHOW TABLE STATUS`
        • `SHOW [GLOBAL|SESSION] VARIABLES`
        • `SHOW WARNINGS`
        • `START TRANSACTION`
        • `TRACE`
        • `TRUNCATE`
        • `UPDATE`
        • `USE`
      • Constraints
      • Generated Columns
      • Character Set
    • Configuration
      • tidb-server
        • MySQL System Variables
        • TiDB Specific System Variables
        • Configuration Flags
        • Configuration File
      • pd-server
        • Configuration Flags
      • tikv-server
        • Configuration Flags
    • Security
      • Security Compatibility with MySQL
      • The TiDB Access Privilege System
      • TiDB User Account Management
    • Transactions
      • Overview
      • Transaction Model
      • Isolation Levels
      • Pessimistic Transactions
    • System Databases
      • `mysql`
      • `information_schema`
    • Errors Codes
    • Supported Client Drivers
    • Garbage Collection (GC)
    • Performance
      • Overview
      • Understanding the Query Execution Plan
      • Introduction to Statistics
      • Optimizer Hints
      • Tune TiKV
    • Best Practices
    • TiSpark
    • Tools
      • Mydumper
      • Syncer
      • Loader
      • TiDB Data Migration
        • Overview
        • Restrictions
        • Features
          • Table Routing
          • Black and White Lists
          • Binlog Event Filter
          • Column Mapping
          • Synchronization Delay Monitoring
          • Sharding Support
            • Introduction
            • Restrictions
            • Handle Sharding DDL Locks Manually
        • Usage Scenarios
          • Simple Scenario
          • Shard Merge Scenario
        • Deploy
        • Configure
          • Overview
          • Task Configuration
        • Monitor
        • Manage the Task
        • Cluster Operations
        • Migrate from MySQL compatible database
          • Migrate from Aurora
        • Troubleshoot
      • TiDB Lightning
        • Overview
        • Deployment
        • Checkpoints
        • Table Filter
        • CSV Support
        • Monitor
        • Troubleshoot
        • FAQ
      • TiDB Binlog
        • Overview
        • Deploy
        • Monitor
        • Maintain
        • Upgrade
      • PD Control
      • PD Recover
      • TiKV Control
      • TiDB Control
      • Download
    • Key Monitoring Metrics
      • Overview
      • TiDB
      • PD
      • TiKV
    • Adopters
  • FAQs
    • TiDB FAQs
    • TiDB Lightning FAQs
    • Upgrade FAQs
  • Support
    • Support Resources
    • Report an Issue
  • Contribute
    • Contribute to TiDB
    • Improve the Docs
  • Roadmap
  • Releases
    • v3.0
      • 3.0.0-rc.2
      • 3.0.0-rc.1
      • 3.0.0-beta.1
      • 3.0.0-beta
    • v2.1
      • 2.1.12
      • 2.1.11
      • 2.1.10
      • 2.1.9
      • 2.1.8
      • 2.1.7
      • 2.1.6
      • 2.1.5
      • 2.1.4
      • 2.1.3
      • 2.1.2
      • 2.1.1
      • 2.1 GA
      • 2.1 RC5
      • 2.1 RC4
      • 2.1 RC3
      • 2.1 RC2
      • 2.1 RC1
      • 2.1 Beta
    • v2.0
      • 2.0.11
      • 2.0.10
      • 2.0.9
      • 2.0.8
      • 2.0.7
      • 2.0.6
      • 2.0.5
      • 2.0.4
      • 2.0.3
      • 2.0.2
      • 2.0.1
      • 2.0
      • 2.0 RC5
      • 2.0 RC4
      • 2.0 RC3
      • 2.0 RC1
      • 1.1 Beta
      • 1.1 Alpha
    • v1.0
      • 1.0.8
      • 1.0.7
      • 1.0.6
      • 1.0.5
      • 1.0.4
      • 1.0.3
      • 1.0.2
      • 1.0.1
      • 1.0
      • Pre-GA
      • RC4
      • RC3
      • RC2
      • RC1

TiDB 2.1 Beta Release Notes

On June 29, 2018, TiDB 2.1 Beta is released! Compared with TiDB 2.0, this release has great improvement in stability, SQL optimizer, statistics information, and execution engine.

TiDB

  • SQL Optimizer
    • Optimize the selection range of Index Join to improve the execution performance
    • Optimize correlated subquery, push down Filter, and extend the index range, to improve the efficiency of some queries by orders of magnitude
    • Support Index Hint and Join Hint in the UPDATE and DELETE statements
    • Validate Hint TIDM_SMJ when no available index exists
    • Support pushdown of the ABS, CEIL, FLOOR, IS TRUE, and IS FALSE functions
    • Handle the IF and IFNULL functions especially in the constant folding process
  • SQL Execution Engine
    • Implement parallel Hash Aggregate operators and improve the computing performance of Hash Aggregate by 350% in some scenarios
    • Implement parallel Project operators and improve the performance by 74% in some scenarios
    • Read the data of the Inner table and Outer table of Hash Join concurrently to improve the execution performance
    • Fix incorrect results of INSERT … ON DUPLICATE KEY UPDATE … in some scenarios
    • Fix incorrect results of the CONCAT_WS, FLOOR, CEIL, and DIV built-in functions
  • Server
    • Add the HTTP API to scatter the distribution of table Regions in the TiKV cluster
    • Add the auto_analyze_ratio system variable to control the threshold value of automatic Analyze
    • Add the HTTP API to control whether to open the general log
    • Add the HTTP API to modify the log level online
    • Add the user information in the general log and the slow query log
    • Support the server side cursor
  • Compatibility
    • Support more MySQL syntax
    • Make the bit aggregate function support the ALL parameter
    • Support the SHOW PRIVILEGES statement
  • DML
    • Decrease the memory usage of the INSERT INTO SELECT statement
    • Fix the performance issue of PlanCache
    • Add the tidb_retry_limit system variable to control the automatic retry times of transactions
    • Add the tidb_disable_txn_auto_retry system variable to control whether the transaction tries automatically
    • Fix the accuracy issue of the written data of the time type
    • Support the queue of locally conflicted transactions to optimize the conflicted transaction performance
    • Fix Affected Rows of the UPDATE statement
    • Optimize the statement performance of insert ignore on duplicate key update
  • DDL
    • Optimize the execution speed of the CreateTable statement
    • Optimize the execution speed of ADD INDEX and improve it greatly in some scenarios
    • Fix the issue that the number of added columns by Alter table add column exceeds the limit of the number of table columns
    • Fix the issue that DDL job retries lead to an increasing pressure on TiKV in abnormal conditions
    • Fix the issue that TiDB continuously reloads the schema information in abnormal conditions
    • Do not output the FOREIGN KEY related information in the result of SHOW CREATE TABLE
    • Support the select tidb_is_ddl_owner() statement to facilitate judging whether TiDB is DDL Owner
    • Fix the issue that the index is deleted in the Year type in some scenarios
    • Fix the renaming table issue in the concurrent execution scenario
    • Support the AlterTableForce syntax
    • Support the AlterTableRenameIndex syntax with FromKey and ToKey
    • Add the table name and database name in the output information of admin show ddl jobs

PD

  • Enable Raft PreVote between PD nodes to avoid leader reelection when network recovers after network isolation
  • Optimize the issue that Balance Scheduler schedules small Regions frequently
  • Optimize the hotspot scheduler to improve its adaptability in traffic statistics information jitters
  • Skip the Regions with a large number of rows when scheduling region merge
  • Enable raft learner by default to lower the risk of unavailable data caused by machine failure during scheduling
  • Remove max-replica from pd-recover
  • Add Filter metrics
  • Fix the issue that Region information is not updated after tikv-ctl unsafe recovery
  • Fix the issue that TiKV disk space is used up caused by replica migration in some scenarios
  • Compatibility notes
    • Do not support rolling back to v2.0.x or earlier due to update of the new version storage engine
    • Enable raft learner by default in the new version of PD. If the cluster is upgraded from 1.x to 2.1, the machine should be stopped before upgrade or a rolling update should be first applied to TiKV and then PD

TiKV

  • Upgrade Rust to the nightly-2018-06-14 version
  • Enable Raft PreVote to avoid leader reelection generated when network recovers after network isolation
  • Add a metric to display the number of files and ingest related information in each layer of RocksDB
  • Print key with too many versions when GC works
  • Use static metric to optimize multi-label metric performance (YCSB raw get is improved by 3%)
  • Remove box in multiple modules and use patterns to improve the operating performance (YCSB raw get is improved by 3%)
  • Use asynchronous log to improve the performance of writing logs
  • Add a metric to collect the thread status
  • Decease memory copy times by decreasing box used in the application to improve the performance
"TiDB 2.1 Beta Release Notes" was last updated Nov 23 2018: *: add v1.0 and v2.0 docs subdirectories (#760) (cbc4ffb)
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