- 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
- Deploy
- Hardware Recommendations
- From Binary Tarball
- Orchestrated Deployment
- Geographic Redundancy
- Data Migration with Ansible
- Configure
- Secure
- Transport Layer Security (TLS)
- Generate Self-signed Certificates
- Monitor
- Migrate
- Maintain
- Common Ansible Operations
- Backup and Restore
- Use BR (recommended)
- Identify Abnormal Queries
- Scale
- Upgrade
- Troubleshoot
- Reference
- SQL
- MySQL Compatibility
- SQL Language Structure
- Attributes
- Data Types
- 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
- Window Functions
- Miscellaneous Functions
- Precision Math
- List of Expressions for Pushdown
- SQL Statements
ADD COLUMN
ADD INDEX
ADMIN
ADMIN CANCEL DDL
ADMIN CHECKSUM TABLE
ADMIN CHECK [TABLE|INDEX]
ADMIN SHOW DDL [JOBS|QUERIES]
ALTER DATABASE
ALTER INSTANCE
ALTER TABLE
ALTER USER
ANALYZE TABLE
BEGIN
CHANGE COLUMN
COMMIT
CREATE DATABASE
CREATE INDEX
CREATE ROLE
CREATE TABLE LIKE
CREATE TABLE
CREATE USER
CREATE VIEW
DEALLOCATE
DELETE
DESC
DESCRIBE
DO
DROP COLUMN
DROP DATABASE
DROP INDEX
DROP ROLE
DROP TABLE
DROP USER
DROP VIEW
EXECUTE
EXPLAIN ANALYZE
EXPLAIN
FLUSH PRIVILEGES
FLUSH STATUS
FLUSH TABLES
GRANT <privileges>
GRANT <role>
INSERT
KILL [TIDB]
LOAD DATA
LOAD STATS
MODIFY COLUMN
PREPARE
RECOVER TABLE
RENAME INDEX
RENAME TABLE
REPLACE
REVOKE <privileges>
REVOKE <role>
ROLLBACK
SELECT
SET DEFAULT ROLE
SET [NAMES|CHARACTER SET]
SET PASSWORD
SET ROLE
SET TRANSACTION
SET [GLOBAL|SESSION] <variable>
SHOW ANALYZE STATUS
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 STATUS
SHOW [FULL] TABLES
SHOW TABLE REGIONS
SHOW TABLE STATUS
SHOW [GLOBAL|SESSION] VARIABLES
SHOW WARNINGS
SPLIT REGION
START TRANSACTION
TRACE
TRUNCATE
UPDATE
USE
- Constraints
- Generated Columns
- Partitioning
- Character Set
- SQL Mode
- Views
- Configuration
- Security
- Transactions
- System Databases
- Errors Codes
- Supported Client Drivers
- Garbage Collection (GC)
- Performance
- Overview
- Understanding the Query Execution Plan
- The Blocklist of Optimization Rules and Expression Pushdown
- Introduction to Statistics
- TopN and Limit Push Down
- Optimizer Hints
- Follower Read
- Check the TiDB Cluster Status Using SQL Statements
- Execution Plan Binding
- Statement Summary Table
- Tune TiKV
- Operating System Tuning
- Column Pruning
- Key Monitoring Metrics
- Alert Rules
- Best Practices
- TiSpark
- TiKV
- TiFlash
- TiDB Binlog
- Tools
- Overview
- Use Cases
- Download
- TiDB Operator
- Table Filter
- Backup & Restore (BR)
- Mydumper
- Syncer
- Loader
- Data Migration
- TiDB Lightning
- sync-diff-inspector
- PD Control
- PD Recover
- TiKV Control
- TiDB Control
- TiDB in Kubernetes
- FAQs
- Support
- Contribute
- Releases
- All Releases
- v3.1
- v3.0
- v2.1
- v2.0
- v1.0
- Glossary
Important
You are viewing the documentation of an older version of the TiDB database (TiDB v3.1).
It is recommended that you use the latest LTS version of the TiDB database.
TiDB 2.0 Release Notes
On April 27, 2018, TiDB 2.0 GA is released! Compared with TiDB 1.0, this release has great improvement in MySQL compatibility, SQL optimizer, executor, and stability.
TiDB
- SQL Optimizer
- Use more compact data structure to reduce the memory usage of statistics information
- Speed up loading statistics information when starting a tidb-server process
- Support updating statistics information dynamically [experimental]
- Optimize the cost model to provide more accurate query cost evaluation
- Use
Count-Min Sketch
to estimate the cost of point queries more accurately - Support analyzing more complex conditions to make full use of indexes
- Support manually specifying the
Join
order using theSTRAIGHT_JOIN
syntax - Use the Stream Aggregation operator when the
GROUP BY
clause is empty to improve the performance - Support using indexes for the
MAX/MIN
function - Optimize the processing algorithms for correlated subqueries to support decorrelating more types of correlated subqueries and transform them to
Left Outer Join
- Extend
IndexLookupJoin
to be used in matching the index prefix
- SQL Execution Engine
- Refactor all operators using the Chunk architecture, improve the execution performance of analytical queries, and reduce memory usage. There is a significant improvement in the TPC-H benchmark result.
- Support the Streaming Aggregation operators pushdown
- Optimize the
Insert Into Ignore
statement to improve the performance by over 10 times - Optimize the
Insert On Duplicate Key Update
statement to improve the performance by over 10 times - Optimize
Load Data
to improve the performance by over 10 times - Push down more data types and functions to TiKV
- Support computing the memory usage of physical operators, and specifying the processing behavior in the configuration file and system variables when the memory usage exceeds the threshold
- Support limiting the memory usage by a single SQL statement to reduce the risk of OOM
- Support using implicit RowID in CRUD operations
- Improve the performance of point queries
- Server
- Support the Proxy Protocol
- Add more monitoring metrics and refine the log
- Support validating the configuration files
- Support obtaining the information of TiDB parameters through HTTP API
- Resolve Lock in the Batch mode to speed up garbage collection
- Support multi-threaded garbage collection
- Support TLS
- Compatibility
- Support more MySQL syntaxes
- Support modifying the
lower_case_table_names
system variable in the configuration file to support the OGG data replication tool - Improve compatibility with the Navicat management tool
- Support displaying the table creating time in
Information_Schema
- Fix the issue that the return types of some functions/expressions differ from MySQL
- Improve compatibility with JDBC
- Support more SQL Modes
- DDL
- Optimize the
Add Index
operation to greatly improve the execution speed in some scenarios - Attach a lower priority to the
Add Index
operation to reduce the impact on online business - Output more detailed status information of the DDL jobs in
Admin Show DDL Jobs
- Support querying the original statements of currently running DDL jobs using
Admin Show DDL Job Queries JobID
- Support recovering the index data using
Admin Recover Index
for disaster recovery - Support modifying Table Options using the
Alter
statement
- Optimize the
PD
- Support
Region Merge
, to merge empty Regions after deleting data [experimental] - Support
Raft Learner
[experimental] - Optimize the scheduler
- Make the scheduler to adapt to different Region sizes
- Improve the priority and speed of restoring data during TiKV outage
- Speed up data transferring when removing a TiKV node
- Optimize the scheduling policies to prevent the disks from becoming full when the space of TiKV nodes is insufficient
- Improve the scheduling efficiency of the balance-leader scheduler
- Reduce the scheduling overhead of the balance-region scheduler
- Optimize the execution efficiency of the the hot-region scheduler
- Operations interface and configuration
- Support TLS
- Support prioritizing the PD leaders
- Support configuring the scheduling policies based on labels
- Support configuring stores with a specific label not to schedule the Raft leader
- Support splitting Region manually to handle the hotspot in a single Region
- Support scattering a specified Region to manually adjust Region distribution in some cases
- Add check rules for configuration parameters and improve validity check of the configuration items
- Debugging interface
- Add the
Drop Region
debugging interface - Add the interfaces to enumerate the health status of each PD
- Add the
- Statistics
- Add statistics about abnormal Regions
- Add statistics about Region isolation level
- Add scheduling related metrics
- Performance
- Keep the PD leader and the etcd leader together in the same node to improve write performance
- Optimize the performance of Region heartbeat
TiKV
- Features
- Protect critical configuration from incorrect modification
- Support
Region Merge
[experimental] - Add the
Raw DeleteRange
API - Add the
GetMetric
API - Add
Raw Batch Put
,Raw Batch Get
,Raw Batch Delete
andRaw Batch Scan
- Add Column Family options for the RawKV API and support executing operation on a specific Column Family
- Support Streaming and Streaming Aggregation in Coprocessor
- Support configuring the request timeout of Coprocessor
- Carry timestamps with Region heartbeats
- Support modifying some RocksDB parameters online, such as
block-cache-size
- Support configuring the behavior of Coprocessor when it encounters some warnings or errors
- Support starting in the importing data mode to reduce write amplification during the data importing process
- Support manually splitting Region in halves
- Improve the data recovery tool
tikv-ctl
- Return more statistics in Coprocessor to guide the behavior of TiDB
- Support the
ImportSST
API to import SST files [experimental] - Add the TiKV Importer binary to integrate with TiDB Lightning to import data quickly [experimental]
- Performance
- Optimize read performance using
ReadPool
and increase theraw_get/get/batch_get
by 30% - Improve metrics performance
- Inform PD immediately once the Raft snapshot process is completed to speed up balancing
- Solve performance jitter caused by RocksDB flushing
- Optimize the space reclaiming mechanism after deleting data
- Speed up garbage cleaning while starting the server
- Reduce the I/O overhead during replica migration using
DeleteFilesInRanges
- Optimize read performance using
- Stability
- Fix the issue that gRPC call does not get returned when the PD leader switches
- Fix the issue that it is slow to offline nodes caused by snapshots
- Limit the temporary space usage consumed by migrating replicas
- Report the Regions that cannot elect a leader for a long time
- Update the Region size information in time according to compaction events
- Limit the size of scan lock to avoid request timeout
- Limit the memory usage when receiving snapshots to avoid OOM
- Increase the speed of CI test
- Fix the OOM issue caused by too many snapshots
- Configure
keepalive
of gRPC - Fix the OOM issue caused by an increase of the Region number
TiSpark
TiSpark uses a separate version number. The current TiSpark version is 1.0 GA. The components of TiSpark 1.0 provide distributed computing of TiDB data using Apache Spark.
- Provide a gRPC communication framework to read data from TiKV
- Provide encoding and decoding of TiKV component data and communication protocol
- Provide calculation pushdown, which includes:
- Aggregate pushdown
- Predicate pushdown
- TopN pushdown
- Limit pushdown
- Provide index related support
- Transform predicate into Region key range or secondary index
- Optimize
Index Only
queries - Adaptively downgrade index scan to table scan per Region
- Provide cost-based optimization
- Support statistics
- Select index
- Estimate broadcast table cost
- Provide support for multiple Spark interfaces
- Support Spark Shell
- Support ThriftServer/JDBC
- Support Spark-SQL interaction
- Support PySpark Shell
- Support SparkR
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