Updated on 2026-10-19 GMT+08:00

Best Practices for the Druid Connection Pool

This section describes the core parameters and configuration examples of the Druid connection pool for TaurusDB application access. TaurusDB is compatible with the MySQL protocol. Applications can access TaurusDB using the standard MySQL JDBC driver. The core advantages of Druid lie in its built-in SQL monitoring, connection keepalive, and connection pool-level automatic reconnection.

Recommended Versions

Component	Recommended Version	Description
Druid	1.2.20 or later. 1.2.24 or a later stable version is recommended for production.	The keepAlive feature in versions earlier than 1.2.6 has defects.
MySQL JDBC driver	mysql-connector-j 8.0.33 or later	It is compatible with the TaurusDB 8.0 kernel protocol.
JDK	Java 8 or later	Druid 1.2.x supports Java 8 and later.

Parameter Settings

**Table 1** Mandatory parameters
Parameter	Description	Example
url	JDBC connection URL	jdbc:mysql://host:3306/mydb
username	Database account	root
password	Account password	******

**Table 2** Connection pool capacity parameters
Parameter	Default Value	Description
initialSize	0	Number of physical connections created during initialization
minIdle	0	Minimum number of idle connections (lower limit for keepalive)
maxActive	8	Maximum number of active connections
maxWait	-1	Maximum wait time (ms) to get a connection

**Table 3** Connection eviction and keepalive parameters
Parameter	Default Value	Description	Recommended Value	Note
timeBetweenEvictionRunsMillis	60000	Eviction thread interval (ms)	60000 (60s)	Decrease the value if you want to reclaim idle connections faster. Increase it if you are sensitive to database check load or thread overhead.
minEvictableIdleTimeMillis	1800000	Minimum idle time before eviction (ms)	1800000 (30 min)	Decrease the value if you want to quickly release idle connections. Increase it if you want connections to persist to reduce the overhead of re-establishing connections.
maxEvictableIdleTimeMillis	25200000	Maximum idle time before forcible eviction (ms)	25200000 (7 h)	Decrease this value to be lower than the database's wait_timeout if it is relatively small, preventing passive disconnection. Increase it if you want connections to be reused for a longer period.
keepAlive	false	Whether to send heartbeats to keep connections in minIdle alive	true	Set this parameter to true in primary/standby switchover or idle disconnection scenarios. Set it to false if the number of connections is small and creating a new connection each time is acceptable.
keepAliveBetweenTimeMillis	120000	Keepalive heartbeat interval (ms)	120000	Decrease this value to be lower than the database's wait_timeout if it is relatively small. Increase it if you are sensitive to check overhead.
validationQuery	None	Validation SQL statement, for example, SELECT 1	SELECT 1	This parameter is mandatory. Otherwise, checks such as testOnBorrow and testWhileIdle do not take effect.
validationQueryTimeout	-1	Validation SQL timeout (s)	3 (s)	Timeout interval of validationQuery. The default value is -1 (infinite waiting). Keeping the default value in the production environment is not recommended as it may block the validation thread.
testOnBorrow	false	Whether to validate on connection acquisition	false	Setting it to true has a significant impact on performance. Keeping it as false is recommended.
testOnReturn	false	Whether to validate on connection return	false	Generally, this function does not need to be enabled. The probability that a connection becomes invalid before being returned is extremely low. Enabling this function increases overheads. Consider enabling it only in environments with extremely poor connection quality.
testWhileIdle	true	Whether to validate idle connections	true	Minimum-overhead fallback health check. You are advised to set this parameter to true.

Configuration Example

datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://<taurusdb_vip>:3306/<db>?useUnicode=true&characterEncoding=utf8& &serverTimezone=Asia/Shanghai
    username: <user>
    password: <password>
    druid:
      initial-size: 5
      min-idle: 5
      max-active: 20
      max-wait: 60000
      validation-query: SELECT 1
      test-while-idle: true
      test-on-borrow: false
      keep-alive: true
      keep-alive-between-time-millis: 120000
      time-between-eviction-runs-millis: 60000
      min-evictable-idle-time-millis: 1800000

Parent Topic: Best Practices for Client Connection Pools

Best Practices for the Druid Connection Pool

Recommended Versions

Parameter Settings

Configuration Example

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