- 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 3.0 Beta Release Notes
On January 19, 2019, TiDB 3.0 Beta is released. The corresponding TiDB Ansible 3.0 Beta is also released. TiDB 3.0 Beta builds on TiDB 2.1 with an added focus in stability, the SQL optimizer, statistics, and the execution engine.
TiDB
- New Features
- Support Views
- Support Window Functions
- Support Range Partitioning
- Support Hash Partitioning
- SQL Optimizer
- Re-support the optimization rule of
AggregationElimination
#7676 - Optimize the
NOT EXISTS
subquery and convert it to Anti Semi Join #7842 - Add the
tidb_enable_cascades_planner
variable to support the new Cascades optimizer. Currently, the Cascades optimizer is not yet fully implemented and is turned off by default #7879 - Support using Index Join in transactions #7877
- Optimize the constant propagation on the Outer Join, so that the filtering conditions related to the Outer table in the Join result can be pushed down through the Outer Join to the Outer table, reducing the useless calculation of the Outer Join and improving the execution performance #7794
- Adjust the optimization rule of Projection Elimination to the position after the Aggregation Elimination, to avoid redundant
Project
operators #7909 - Optimize the
IFNULL
function and eliminate this function when the input parameter has a non-NULL attribute #7924 - Support Range for
_tidb_rowid
construction queries, to avoid full table scan and reduce cluster stress #8047 - Optimize the
IN
subquery to do the Inner Join after the aggregation, and add thetidb_opt_insubq_to_join_and_agg
variable to control whether to enable this optimization rule and open it by default #7531 - Support using subqueries in the
DO
statement #8343 - Add the optimization rule of Outer Join elimination to reduce unnecessary table scan and Join operations and improve execution performance #8021
- Modify the Hint behavior of the
TIDB_INLJ
optimizer, and the optimizer will use the table specified in Hint as the Inner table of Index Join #8243 - Use
PointGet
in a wide range so that it can be used when the execution plan cache of thePrepare
statement takes effect #8108 - Introduce the greedy
Join Reorder
algorithm to optimize the join order selection when joining multiple tables #8394 - Support View #8757
- Support Window Function #8630
- Return warning to the client when
TIDB_INLJ
is not in effect, to enhance usability #9037 - Support deducing the statistics for filtered data based on filtering conditions and table statistics #7921
- Improve the Partition Pruning optimization rule of Range Partition #8885
- Re-support the optimization rule of
- SQL Executor
- Optimize the
Merge Join
operator to support the emptyON
condition #9037 - Optimize the log and print the user variables used when executing the
EXECUTE
statement #7684 - Optimize the log to print slow query information for the
COMMIT
statement #7951 - Support the
EXPLAIN ANALYZE
feature to make the SQL tuning process easier #7827 - Optimize the write performance of wide tables with many columns #7935
- Support
admin show next_row_id
#8242 - Add the
tidb_init_chunk_size
variable to control the size of the initial Chunk used by the execution engine #8480 - Improve
shard_row_id_bits
and cross-check the auto-increment ID #8936
- Optimize the
Prepare
Statement- Prohibit adding the
Prepare
statement containing subqueries to the query plan cache to guarantee the query plan is correct when different user variables are input #8064 - Optimize the query plan cache to guarantee the plan can be cached when the statement contains non-deterministic functions #8105
- Optimize the query plan cache to guarantee the query plan of
DELETE
/UPDATE
/INSERT
can be cached #8107 - Optimize the query plan cache to remove the corresponding plan when executing the
DEALLOCATE
statement #8332 - Optimize the query plan cache to avoid the TiDB OOM issue caused by caching too many plans by limiting the memory usage #8339
- Optimize the
Prepare
statement to support using the?
placeholder in theORDER BY
/GROUP BY
/LIMIT
clause #8206
- Prohibit adding the
- Privilege Management
- Server
- Support the
Trace
feature #9029 - Support the plugin framework #8788
- Support using
unix_socket
and TCP simultaneously to connect to the database #8836 - Support the
interactive_timeout
system variable #8573 - Support the
wait_timeout
system variable #8346 - Support splitting a transaction into multiple transactions based on the number of statements using the
tidb_batch_commit
variable #8293 - Support using the
ADMIN SHOW SLOW
statement to check slow logs #7785
- Support the
- Compatibility
- Support the
ALLOW_INVALID_DATES
SQL mode #9027 - Improve
LoadData
fault-tolerance for the CSV file #9005 - Support the MySQL 320 handshake protocol #8812
- Support using the unsigned
bigint
column as the auto-increment column #8181 - Support the
SHOW CREATE DATABASE IF NOT EXISTS
syntax #8926 - Abandon the predicate pushdown operation when the filtering condition contains a user variable to improve the compatibility with MySQL’s behavior of using user variables to mock the Window Function behavior #8412
- Support the
- DDL
Tools
- TiDB Lightning
PD
- Add
RegionStorage
to store Region metadata separately #1237 - Add shuffle hot Region scheduler #1361
- Add scheduling parameter related metrics #1406
- Add cluster label related metrics #1402
- Add the importing data simulator #1263
- Fix the
Watch
issue about leader election #1396
TiKV
- Support distributed GC #3179
- Check RocksDB Level 0 files before applying snapshots to avoid Write Stall #3606
- Support reverse
raw_scan
andraw_batch_scan
#3742 - Support using HTTP to obtain monitoring information #3855
- Support DST better #3786
- Support receiving and sending Raft messages in batch #3931
- Introduce a new storage engine Titan #3985
- Upgrade gRPC to v1.17.2 #4023
- Support receiving the client requests and sending replies in batch #4043
- Support multi-thread Apply #4044
- Support multi-thread Raftstore #4066
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