- 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
- 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
- Miscellaneous Functions
- Precision Math
- 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 TABLE LIKE
CREATE TABLE
CREATE USER
DEALLOCATE
DELETE
DESC
DESCRIBE
DO
DROP COLUMN
DROP DATABASE
DROP INDEX
DROP TABLE
DROP USER
EXECUTE
EXPLAIN ANALYZE
EXPLAIN
FLUSH PRIVILEGES
FLUSH STATUS
FLUSH TABLES
GRANT <privileges>
INSERT
KILL [TIDB]
LOAD DATA
LOAD STATS
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 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 STATUS
SHOW [GLOBAL|SESSION] VARIABLES
SHOW WARNINGS
START TRANSACTION
TRACE
TRUNCATE
UPDATE
USE
- Constraints
- Generated Columns
- Character Set
- Configuration
- Security
- Transactions
- System Databases
- Errors Codes
- Supported Client Drivers
- Garbage Collection (GC)
- Performance
- Key Monitoring Metrics
- Alert Rules
- Best Practices
- TiSpark
- TiDB Binlog
- Tools
- Overview
- Use Cases
- Download
- Mydumper
- Syncer
- Loader
- TiDB Data Migration
- TiDB Lightning
- sync-diff-inspector
- PD Control
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- TiKV Control
- TiDB Control
- FAQs
- Support
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- Releases
- All Releases
- v2.1
- v2.0
- v1.0
- Glossary
You are viewing the documentation of an older version of the TiDB database (TiDB v2.1).
Scale a TiDB cluster
Overview
The capacity of a TiDB cluster can be increased or reduced without affecting online services.
If your TiDB cluster is deployed using TiDB Ansible, see Scale the TiDB Cluster Using TiDB Ansible.
The following part shows you how to add or delete PD, TiKV or TiDB nodes.
About pd-ctl
usage, refer to PD Control User Guide.
PD
Assume we have three PD servers with the following details:
Name | ClientUrls | PeerUrls |
---|---|---|
pd1 | http://host1:2379 | http://host1:2380 |
pd2 | http://host2:2379 | http://host2:2380 |
pd3 | http://host3:2379 | http://host3:2380 |
Get the information about the existing PD nodes through pd-ctl:
./pd-ctl -u http://host1:2379 -i
>> member
Add a node dynamically
Add a new PD server to the current PD cluster by using the parameter join
.
To add pd4
, you just need to specify the client url of any PD server in the PD cluster in the parameter --join
, like:
./bin/pd-server --name=pd4 \
--client-urls="http://host4:2379" \
--peer-urls="http://host4:2380" \
--join="http://host1:2379"
Delete a node dynamically
Delete pd4
through pd-ctl:
./pd-ctl -u http://host1:2379
>> member delete name pd4
Migrate a node dynamically
If you want to migrate a node to a new machine, you need to, first of all, add a node on the new machine and then delete the node on the old machine. As you can just migrate one node at a time, if you want to migrate multiple nodes, you need to repeat the above steps until you have migrated all nodes. After completing each step, you can verify the process by checking the information of all nodes.
TiKV
Get the information about the existing TiKV nodes through pd-ctl:
./pd-ctl -u http://host1:2379
>> store
Add a node dynamically
It is very easy to add a new TiKV server dynamically. You just need to start a TiKV server on the new machine. The newly started TiKV server will automatically register in the existing PD of the cluster. To reduce the pressure of the existing TiKV servers, PD loads balance automatically, which means PD gradually migrates some data to the new TiKV server.
Delete a node dynamically
To delete (make it offline) a TiKV server safely, you need to inform PD in advance. After that, PD is able to migrate the data on this TiKV server to other TiKV servers, ensuring that data have enough replicas.
Assume that you need to delete the TiKV server with a store id 1, you can complete this through pd-ctl:
./pd-ctl -u http://host1:2379
>> store delete 1
Then you can check the state of this TiKV:
./pd-ctl -u http://host1:2379
>> store 1
{
"store": {
"id": 1,
"address": "127.0.0.1:20160",
"state": 1,
"state_name": "Offline"
},
"status": {
...
}
}
You can verify the state of this store using state_name
:
- Up: This store is in service.
- Disconnected: The heartbeats of this store cannot be detected currently, which might be caused by a failure or network interruption.
- Down: PD does not receive heartbeats from the TiKV store for more than an hour (the time can be configured using
max-down-time
). At this time, PD adds a replica for the data on this store. - Offline: The store is in the process of transferring its Regions to other nodes. The state name is misleading: the store is available and even continuing to lead some of its Regions.
- Tombstone: This store is shut down and has no data on it, so the instance can be deleted.
Migrate a node dynamically
To migrate TiKV servers to a new machine, you also need to add nodes on the new machine and then make all nodes on the old machine offline. In the process of migration, you can add all machines in the new cluster to the existing cluster, then make old nodes offline one by one. To verify whether a node has been made offline, you can check the state information of the node in process. After verifying, you can make the next node offline.
TiDB
TiDB is a stateless server, which means it can be added or deleted directly. It should be noted that if you deploy a proxy (such as HAProxy) in front of TiDB, you need to update the proxy configuration and reload it.