- 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
- Identify Abnormal Queries
- Scale
- Upgrade
- Troubleshoot
- Reference
- SQL
- MySQL Compatibility
- SQL Language Structure
- 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 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
- 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
- TiDB Binlog
- Tools
- TiDB in Kubernetes
- FAQs
- Support
- Contribute
- Releases
- All Releases
- v3.0
- v2.1
- v2.0
- v1.0
- Glossary
You are viewing the documentation of an older version of the TiDB database (TiDB v3.0).
TiDB Cluster Troubleshooting Guide
You can use this guide to help you diagnose and solve basic problems while using TiDB. If your problem is not resolved, please collect the following information and create an issue:
- The exact error message and the operations while the error occurs
- The state of all the components
- The
error
/fatal
/panic
information in the log of the component that reports the error - The configuration and deployment topology
- The TiDB component related issue in
dmesg
For other information, see Frequently Asked Questions (FAQ).
Cannot connect to the database
Make sure all the services are started, including
tidb-server
,pd-server
, andtikv-server
.Use the
ps
command to check if all the processes are running.- If a certain process is not running, see the following corresponding sections to diagnose and solve the issue.
- If all the processes are running, check the
tidb-server
log to see if the following messages are displayed:- InformationSchema is out of date: This message is displayed if the
tikv-server
cannot be connected. Check the state and log ofpd-server
andtikv-server
. - panic: This message is displayed if there is an issue with the program. Please provide the detailed panic log and create an issue.
- InformationSchema is out of date: This message is displayed if the
If the data is cleared and the services are re-deployed, make sure that:
- All the data in
tikv-server
andpd-server
are cleared. The specific data is stored intikv-server
and the metadata is stored inpd-server
. If only one of the two servers is cleared, the data will be inconsistent. - After the data in
pd-server
andtikv-server
are cleared and thepd-server
andtikv-server
are restarted, thetidb-server
must be restarted too. The cluster ID is randomly allocated when thepd-server
is initialized. So when the cluster is re-deployed, the cluster ID changes and you need to restart thetidb-server
to get the new cluster ID.
- All the data in
Cannot start tidb-server
See the following for the situations when the tidb-server
cannot be started:
Error in the startup parameters.
See the TiDB configuration and options.
The port is occupied.
Use the
lsof -i:port
command to show all the networking related to a given port and make sure the port to start thetidb-server
is not occupied.Cannot connect to
pd-server
.- Check if the network between TiDB and PD is running smoothly, including whether the network can be pinged or if there is any issue with the Firewall configuration.
- If there is no issue with the network, check the state and log of the
pd-server
process.
Cannot start tikv-server
See the following for the situations when the tikv-server
cannot be started:
- Error in the startup parameters: See the TiKV configuration and options.
- The port is occupied: Use the
lsof -i:port
command to show all the networking related to a given port and make sure the port to start thetikv-server
is not occupied. - Cannot connect to
pd-server
.- Check if the network between TiDB and PD is running smoothly, including whether the network can be pinged or if there is any issue with the Firewall configuration.
- If there is no issue with the network, check the state and log of the
pd-server
process.
- The file is occupied. Do not open two TiKV files on one database file directory.
Cannot start pd-server
See the following for the situations when the pd-server
cannot be started:
Error in the startup parameters.
See the PD configuration and options.
The port is occupied.
Use the
lsof -i:port
command to show all the networking related to a given port and make sure the port to start thepd-server
is not occupied.
The TiDB/TiKV/PD process aborts unexpectedly
Is the process started on the foreground? The process might exit because the client aborts.
Is
nohup+&
run in the command line? This might cause the process to abort because it receives the hup signal. It is recommended to write and run the startup command in a script.
TiDB panic
Please provide the panic log and create an issue.
The connection is rejected
Make sure the network parameters of the operating system are correct, including but not limited to:
- The port in the connection string is consistent with the
tidb-server
starting port. - The firewall is configured correctly.
Open too many files
Before starting the process, make sure the result of ulimit -n
is large enough. It is recommended to set the value to unlimited
or larger than 1000000
.
Database access times out and the system load is too high
First, check the slow query log and see if it is because of some inappropriate SQL statement. If you failed to solve the problem, provide the following information:
- The deployment topology
- How many
tidb-server
/pd-server
/tikv-server
instances are deployed? - How are these instances distributed in the machines?
- How many
- The hardware configuration of the machines where these instances are deployed:
- The number of CPU cores
- The size of the memory
- The type of the disk (SSD or Hard Drive Disk)
- Are they physical machines or virtual machines?
- Are there other services besides the TiDB cluster?
- Are the
pd-server
s andtikv-server
s deployed separately? - What is the current operation?
- Check the CPU thread name using the
top -H
command. - Are there any exceptions in the network or IO monitoring data recently?