- Docs Home
- About TiDB
- Quick Start
- Develop
- Overview
- Quick Start
- Build a TiDB Cluster in TiDB Cloud (Developer Tier)
- CRUD SQL in TiDB
- Build a Simple CRUD App with TiDB
- Example Applications
- Connect to TiDB
- Design Database Schema
- Write Data
- Read Data
- Transaction
- Optimize
- Troubleshoot
- Reference
- Cloud Native Development Environment
- Third-party Support
- Deploy
- Software and Hardware Requirements
- Environment Configuration Checklist
- Plan Cluster Topology
- Install and Start
- Verify Cluster Status
- Test Cluster Performance
- Migrate
- Overview
- Migration Tools
- Migration Scenarios
- Migrate from Aurora
- Migrate MySQL of Small Datasets
- Migrate MySQL of Large Datasets
- Migrate and Merge MySQL Shards of Small Datasets
- Migrate and Merge MySQL Shards of Large Datasets
- Migrate from CSV Files
- Migrate from SQL Files
- Migrate from One TiDB Cluster to Another TiDB Cluster
- Migrate from TiDB to MySQL-compatible Databases
- Advanced Migration
- Integrate
- Maintain
- Monitor and Alert
- Troubleshoot
- TiDB Troubleshooting Map
- Identify Slow Queries
- Analyze Slow Queries
- SQL Diagnostics
- Identify Expensive Queries Using Top SQL
- Identify Expensive Queries Using Logs
- Statement Summary Tables
- Troubleshoot Hotspot Issues
- Troubleshoot Increased Read and Write Latency
- Save and Restore the On-Site Information of a Cluster
- Troubleshoot Cluster Setup
- Troubleshoot High Disk I/O Usage
- Troubleshoot Lock Conflicts
- Troubleshoot TiFlash
- Troubleshoot Write Conflicts in Optimistic Transactions
- Troubleshoot Inconsistency Between Data and Indexes
- Performance Tuning
- Tuning Guide
- Configuration Tuning
- System Tuning
- Software Tuning
- SQL Tuning
- Overview
- Understanding the Query Execution Plan
- SQL Optimization Process
- Overview
- Logic Optimization
- Physical Optimization
- Prepare Execution Plan Cache
- Control Execution Plans
- Tutorials
- TiDB Tools
- Overview
- Use Cases
- Download
- TiUP
- Documentation Map
- Overview
- Terminology and Concepts
- Manage TiUP Components
- FAQ
- Troubleshooting Guide
- Command Reference
- Overview
- TiUP Commands
- TiUP Cluster Commands
- Overview
- tiup cluster audit
- tiup cluster check
- tiup cluster clean
- tiup cluster deploy
- tiup cluster destroy
- tiup cluster disable
- tiup cluster display
- tiup cluster edit-config
- tiup cluster enable
- tiup cluster help
- tiup cluster import
- tiup cluster list
- tiup cluster patch
- tiup cluster prune
- tiup cluster reload
- tiup cluster rename
- tiup cluster replay
- tiup cluster restart
- tiup cluster scale-in
- tiup cluster scale-out
- tiup cluster start
- tiup cluster stop
- tiup cluster template
- tiup cluster upgrade
- TiUP DM Commands
- Overview
- tiup dm audit
- tiup dm deploy
- tiup dm destroy
- tiup dm disable
- tiup dm display
- tiup dm edit-config
- tiup dm enable
- tiup dm help
- tiup dm import
- tiup dm list
- tiup dm patch
- tiup dm prune
- tiup dm reload
- tiup dm replay
- tiup dm restart
- tiup dm scale-in
- tiup dm scale-out
- tiup dm start
- tiup dm stop
- tiup dm template
- tiup dm upgrade
- TiDB Cluster Topology Reference
- DM Cluster Topology Reference
- Mirror Reference Guide
- TiUP Components
- PingCAP Clinic Diagnostic Service
- TiDB Operator
- Dumpling
- TiDB Lightning
- TiDB Data Migration
- About TiDB Data Migration
- Architecture
- Quick Start
- Deploy a DM cluster
- Tutorials
- Advanced Tutorials
- Maintain
- Cluster Upgrade
- Tools
- Performance Tuning
- Manage Data Sources
- Manage Tasks
- Export and Import Data Sources and Task Configurations of Clusters
- Handle Alerts
- Daily Check
- Reference
- Architecture
- Command Line
- Configuration Files
- OpenAPI
- Compatibility Catalog
- Secure
- Monitoring and Alerts
- Error Codes
- Glossary
- Example
- Troubleshoot
- Release Notes
- Backup & Restore (BR)
- TiDB Binlog
- TiCDC
- Dumpling
- sync-diff-inspector
- TiSpark
- Reference
- Cluster Architecture
- Key Monitoring Metrics
- Secure
- Privileges
- SQL
- SQL Language Structure and Syntax
- SQL Statements
ADD COLUMN
ADD INDEX
ADMIN
ADMIN CANCEL DDL
ADMIN CHECKSUM TABLE
ADMIN CHECK [TABLE|INDEX]
ADMIN SHOW DDL [JOBS|QUERIES]
ADMIN SHOW TELEMETRY
ALTER DATABASE
ALTER INDEX
ALTER INSTANCE
ALTER PLACEMENT POLICY
ALTER TABLE
ALTER TABLE COMPACT
ALTER USER
ANALYZE TABLE
BACKUP
BATCH
BEGIN
CHANGE COLUMN
COMMIT
CHANGE DRAINER
CHANGE PUMP
CREATE [GLOBAL|SESSION] BINDING
CREATE DATABASE
CREATE INDEX
CREATE PLACEMENT POLICY
CREATE ROLE
CREATE SEQUENCE
CREATE TABLE LIKE
CREATE TABLE
CREATE USER
CREATE VIEW
DEALLOCATE
DELETE
DESC
DESCRIBE
DO
DROP [GLOBAL|SESSION] BINDING
DROP COLUMN
DROP DATABASE
DROP INDEX
DROP PLACEMENT POLICY
DROP ROLE
DROP SEQUENCE
DROP STATS
DROP TABLE
DROP USER
DROP VIEW
EXECUTE
EXPLAIN ANALYZE
EXPLAIN
FLASHBACK TABLE
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
RESTORE
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 [BACKUPS|RESTORES]
SHOW [GLOBAL|SESSION] BINDINGS
SHOW BUILTINS
SHOW CHARACTER SET
SHOW COLLATION
SHOW [FULL] COLUMNS FROM
SHOW CONFIG
SHOW CREATE PLACEMENT POLICY
SHOW CREATE SEQUENCE
SHOW CREATE TABLE
SHOW CREATE USER
SHOW DATABASES
SHOW DRAINER STATUS
SHOW ENGINES
SHOW ERRORS
SHOW [FULL] FIELDS FROM
SHOW GRANTS
SHOW INDEX [FROM|IN]
SHOW INDEXES [FROM|IN]
SHOW KEYS [FROM|IN]
SHOW MASTER STATUS
SHOW PLACEMENT
SHOW PLACEMENT FOR
SHOW PLACEMENT LABELS
SHOW PLUGINS
SHOW PRIVILEGES
SHOW [FULL] PROCESSSLIST
SHOW PROFILES
SHOW PUMP STATUS
SHOW SCHEMAS
SHOW STATS_HEALTHY
SHOW STATS_HISTOGRAMS
SHOW STATS_META
SHOW STATUS
SHOW TABLE NEXT_ROW_ID
SHOW TABLE REGIONS
SHOW TABLE STATUS
SHOW [FULL] TABLES
SHOW [GLOBAL|SESSION] VARIABLES
SHOW WARNINGS
SHUTDOWN
SPLIT REGION
START TRANSACTION
TABLE
TRACE
TRUNCATE
UPDATE
USE
WITH
- Data Types
- Functions and Operators
- Overview
- 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
- Locking Functions
- Information Functions
- JSON Functions
- Aggregate (GROUP BY) Functions
- Window Functions
- Miscellaneous Functions
- Precision Math
- Set Operations
- List of Expressions for Pushdown
- TiDB Specific Functions
- Clustered Indexes
- Constraints
- Generated Columns
- SQL Mode
- Table Attributes
- Transactions
- Garbage Collection (GC)
- Views
- Partitioning
- Temporary Tables
- Cached Tables
- Character Set and Collation
- Placement Rules in SQL
- System Tables
mysql
- INFORMATION_SCHEMA
- Overview
ANALYZE_STATUS
CLIENT_ERRORS_SUMMARY_BY_HOST
CLIENT_ERRORS_SUMMARY_BY_USER
CLIENT_ERRORS_SUMMARY_GLOBAL
CHARACTER_SETS
CLUSTER_CONFIG
CLUSTER_HARDWARE
CLUSTER_INFO
CLUSTER_LOAD
CLUSTER_LOG
CLUSTER_SYSTEMINFO
COLLATIONS
COLLATION_CHARACTER_SET_APPLICABILITY
COLUMNS
DATA_LOCK_WAITS
DDL_JOBS
DEADLOCKS
ENGINES
INSPECTION_RESULT
INSPECTION_RULES
INSPECTION_SUMMARY
KEY_COLUMN_USAGE
METRICS_SUMMARY
METRICS_TABLES
PARTITIONS
PLACEMENT_POLICIES
PROCESSLIST
REFERENTIAL_CONSTRAINTS
SCHEMATA
SEQUENCES
SESSION_VARIABLES
SLOW_QUERY
STATISTICS
TABLES
TABLE_CONSTRAINTS
TABLE_STORAGE_STATS
TIDB_HOT_REGIONS
TIDB_HOT_REGIONS_HISTORY
TIDB_INDEXES
TIDB_SERVERS_INFO
TIDB_TRX
TIFLASH_REPLICA
TIKV_REGION_PEERS
TIKV_REGION_STATUS
TIKV_STORE_STATUS
USER_PRIVILEGES
VIEWS
METRICS_SCHEMA
- UI
- TiDB Dashboard
- Overview
- Maintain
- Access
- Overview Page
- Cluster Info Page
- Top SQL Page
- Key Visualizer Page
- Metrics Relation Graph
- SQL Statements Analysis
- Slow Queries Page
- Cluster Diagnostics
- Search Logs Page
- Instance Profiling
- Session Management and Configuration
- FAQ
- CLI
- Command Line Flags
- Configuration File Parameters
- System Variables
- Storage Engines
- Telemetry
- Errors Codes
- Table Filter
- Schedule Replicas by Topology Labels
- FAQs
- Release Notes
- All Releases
- Release Timeline
- TiDB Versioning
- v6.1
- v6.0
- v5.4
- v5.3
- v5.2
- v5.1
- v5.0
- v4.0
- v3.1
- v3.0
- v2.1
- v2.0
- v1.0
- Glossary
TiDB 5.1.2 Release Notes
Release Date: September 27, 2021
TiDB version: 5.1.2
Compatibility changes
TiDB
The following bug fixes change execution results, which might cause upgrade incompatibilities:
- Fix the issue that
greatest(datetime) union null
returns empty string #26532 - Fix the issue that the
having
clause might not work correctly #26496 - Fix the wrong execution results that occur when the collations around the
between
expression are different #27146 - Fix the wrong execution results that occur when the column in the
group_concat
function has a non-bin collation #27429 - Fix an issue that using a
count(distinct)
expression on multiple columns returns wrong result when the new collation is enabled #27091 - Fix the result wrong that occurs when the argument of the
extract
function is a negative duration #27236 - Fix the issue that inserting an invalid date does not report an error when the
SQL_MODE
is 'STRICT_TRANS_TABLES' #26762 - Fix the issue that using an invalid default date does not report an error when the
SQL_MODE
is 'NO_ZERO_IN_DATE' #26766
- Fix the issue that
Tools
TiCDC
- Set the compatible version from
5.1.0-alpha
to5.2.0-alpha
#2659
- Set the compatible version from
Improvements
TiDB
- Trigger auto-analyze by histogram row count and increase the accuracy of this trigger action #24237
TiKV
PD
TiFlash
- Support the
DATE()
function - Add Grafana panels for write throughput per instance
- Optimize the performance of the
leader-read
process - Accelerate the process of canceling MPP tasks
- Support the
Tools
TiCDC
- Optimize memory management when the Unified Sorter is using memory to sort data #2553
- Optimize workerpool for fewer goroutines when concurrency is high #2211
- Reduce goroutine usage when a table's Region transfer away from a TiKV node #2284
- Add a global gRPC connection pool and share gRPC connections among KV clients #2534
- Prohibit operating TiCDC clusters across major and minor versions #2599
Dumpling
- Support backing up MySQL-compatible databases that do not support
START TRANSACTION ... WITH CONSISTENT SNAPSHOT
andSHOW CREATE TABLE
#309
- Support backing up MySQL-compatible databases that do not support
Bug fixes
TiDB
- Fix the potential wrong results of index hash join when the hash column is the
ENUM
type #27893 - Fix a batch client bug that recycle idle connection might block sending requests in some rare cases #27678
- Fix the issue that the overflow check of the
FLOAT64
type is different with that of MySQL #23897 - Fix the issue that TiDB returns an
unknow
error while it should return thepd is timeout
error #26147 - Fix the wrong character set and collation for the
case when
expression #26662 - Fix the potential
can not found column in Schema column
error for MPP queries #28148 - Fix a bug that TiDB might panic when TiFlash is shutting down #28096
- Fix the issue of wrong range caused by using
enum like 'x%'
#27130 - Fix the Common Table Expression (CTE) dead lock issue when used with IndexLookupJoin #27410
- Fix a bug that retryable deadlocks are incorrectly recorded into the
INFORMATION_SCHEMA.DEADLOCKS
table #27400 - Fix the issue that the
TABLESAMPLE
query result from partitioned tables is not sorted as expected #27349 - Remove the unused
/debug/sub-optimal-plan
HTTP API #27265 - Fix a bug that the query might return wrong results when the hash partitioned table deals with unsigned data #26569
- Fix a bug that creating partition fails if
NO_UNSIGNED_SUBTRACTION
is set #26765 - Fix the issue that the
distinct
flag is missing whenApply
is converted toJoin
#26958 - Set a block duration for the newly recovered TiFlash node to avoid blocking queries during this time #26897
- Fix a bug that might occur when the CTE is referenced more than once #26212
- Fix a CTE bug when MergeJoin is used #25474
- Fix a bug that the
SELECT FOR UPDATE
statement does not correctly lock the data when a normal table joins a partitioned table #26251 - Fix the issue that the
SELECT FOR UPDATE
statement returns an error when a normal table joins a partitioned table #26250 - Fix the issue that
PointGet
does not use the lite version of resolving lock #26562
- Fix the potential wrong results of index hash join when the hash column is the
TiKV
- Fix a panic issue that occurs after TiKV is upgraded from v3.x to later versions #10902
- Fix the potential disk full issue caused by corrupted snapshot files #10813
- Make the slow log of TiKV coprocessor only consider the time spent on processing requests #10841
- Drop log instead of blocking threads when the slogger thread is overloaded and the queue is filled up #10841
- Fix a panic issue that occurs when processing Coprocessor requests times out #10852
- Fix the TiKV panic issue that occurs when upgrading from a pre-5.0 version with Titan enabled #10842
- Fix the issue that TiKV of a newer version cannot be rolled back to v5.0.x #10842
- Fix the issue that TiKV might delete files before ingesting data to RocksDB #10438
- Fix the parsing failure caused by the left pessimistic locks #26404
PD
- Fix the issue that PD does not fix the down peers in time #4077
- Fix the issue that the replica count of the default placement rules stays constant after
replication.max-replicas
is updated #3886 - Fix a bug that PD might panic when scaling out TiKV #3868
- Fix a bug that the hot Region scheduler cannot work when the cluster has the evict leader scheduler #3697
TiFlash
- Fix the issue of unexpected results when TiFlash fails to establish MPP connections
- Fix the potential issue of data inconsistency that occurs when TiFlash is deployed on multiple disks
- Fix a bug that MPP queries get wrong results when TiFlash server is under high load
- Fix a potential bug that MPP queries hang forever
- Fix the panic issue when operating store initialization and DDL simultaneously
- Fix a bug of incorrect results that occurs when queries contain filters like
CONSTANT
,<
,<=
,>
,>=
, orCOLUMN
- Fix the potential panic issue when
Snapshot
is applied simultaneously with multiple DDL operations - Fix the issue that the store size in metrics is inaccurate under heavy writing
- Fix the potential issue that TiFlash cannot garbage-collect the delta data after running for a long time
- Fix the issue of wrong results when the new collation is enabled
- Fix the potential panic issue that occurs when resolving locks
- Fix a potential bug that metrics display wrong values
Tools
Backup & Restore (BR)
- Fix the issue that the average speed is not accurate during data backup and restore #1405
Dumpling
TiCDC
- Fix a bug that the JSON encoding might cause panic when processing a string type value that is
string
or[]byte
#2758 - Reduce gRPC window size to avoid OOM #2673
- Fix a gRPC
keepalive
error under high memory pressure #2202 - Fix a bug that an unsigned
tinyint
causes TiCDC to panic #2648 - Fix an empty value issue in TiCDC Open Protocol. An empty value is no longer output when there is no change in one transaction. #2612
- Fix a bug in DDL handling during manual restarts #2603
- Fix the issue that
EtcdWorker
's snapshot isolation might be wrongly violated when managing the metadata #2559 - Fix a bug that multiple processors might write data to the same table when TiCDC is rescheduling the table #2230
- Fix a bug that changefeed might be reset unexpectedly when TiCDC gets the
ErrSchemaStorageTableMiss
error #2422 - Fix a bug that changefeed cannot be removed when TiCDC gets the
ErrGCTTLExceeded
error #2391 - Fix a bug that TiCDC fails to synchronize large tables to cdclog #1259 #2424
- Fix a bug that the JSON encoding might cause panic when processing a string type value that is
What’s on this page
Was this page helpful?