best mysql datasource properties for grails tomcat jndi - mysql

Question

Most examples of JNDI, mysql 5.6 and tomcat 7 have this defined in DataSource.groovy:
dataSource {
pooled = true
driverClassName = "com.mysql.jdbc.Driver"
dialect = 'org.hibernate.dialect.MySQL5InnoDBDialect'
}
environments:
production {
dataSource {
dbCreate = "update"
jndiName = "java:comp/env/myDatasourceName
}
}
and in the conf/context.xml in tomcat:
<Context>
<WatchedResource>WEB-INF/web.xml</WatchedResource>
<Resource name="myDatasourceName" auth="Container" type="javax.sql.DataSource"
maxActive="100" maxIdle="30" maxWait="10000"
username="root" password="password" driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/my_db_name"/>
</Context>
The question is, is this the correct setup for a basic low volume production system, which should reconnect if the db goes down then up etc?
In the DataSource.xml is a hugely complex example:
dataSource {
dbCreate = "update"
//url = "jdbc:h2:prodDb;MVCC=TRUE;LOCK_TIMEOUT=10099;DB_CLOSE_ON_EXIT=FALSE"
properties {
// Documentation for Tomcat JDBC Pool
// http://tomcat.apache.org/tomcat-7.0-doc/jdbc-pool.html#Common_Attributes
// https://tomcat.apache.org/tomcat-7.0-doc/api/org/apache/tomcat/jdbc/pool/PoolConfiguration.html
jmxEnabled = true
initialSize = 5
maxActive = 50
minIdle = 5
maxIdle = 25
maxWait = 10000
maxAge = 10 * 60000
timeBetweenEvictionRunsMillis = 5000
minEvictableIdleTimeMillis = 60000
validationQuery = "SELECT 1"
validationQueryTimeout = 3
validationInterval = 15000
testOnBorrow = true
testWhileIdle = true
testOnReturn = false
ignoreExceptionOnPreLoad = true
// http://tomcat.apache.org/tomcat-7.0-doc/jdbc-pool.html#JDBC_interceptors
jdbcInterceptors = "ConnectionState;StatementCache(max=200)"
defaultTransactionIsolation = java.sql.Connection.TRANSACTION_READ_COMMITTED // safe default
// controls for leaked connections
abandonWhenPercentageFull = 100 // settings are active only when pool is full
removeAbandonedTimeout = 120000
removeAbandoned = true
// use JMX console to change this setting at runtime
logAbandoned = false // causes stacktrace recording overhead, use only for debugging
/*
// JDBC driver properties
// Mysql as example
dbProperties {
// Mysql specific driver properties
// http://dev.mysql.com/doc/connector-j/en/connector-j-reference-configuration-properties.html
// let Tomcat JDBC Pool handle reconnecting
autoReconnect=false
// truncation behaviour
jdbcCompliantTruncation=false
// mysql 0-date conversion
zeroDateTimeBehavior='convertToNull'
// Tomcat JDBC Pool's StatementCache is used instead, so disable mysql driver's cache
cachePrepStmts=false
cacheCallableStmts=false
// Tomcat JDBC Pool's StatementFinalizer keeps track
dontTrackOpenResources=true
// performance optimization: reduce number of SQLExceptions thrown in mysql driver code
holdResultsOpenOverStatementClose=true
// enable MySQL query cache - using server prep stmts will disable query caching
useServerPrepStmts=false
// metadata caching
cacheServerConfiguration=true
cacheResultSetMetadata=true
metadataCacheSize=100
// timeouts for TCP/IP
connectTimeout=15000
socketTimeout=120000
// timer tuning (disable)
maintainTimeStats=false
enableQueryTimeouts=false
// misc tuning
noDatetimeStringSync=true
}
*/
}
}
Now I dont know what 95% of those parameters do, but I guess I need them all?
What I dont understand is this
surely tomcat will pool the connections, so should pooled=true in the grails dataSource?
Surely tomcat will handle reconnecting and validation of connection, so why define validationQuery = "SELECT 1"? Expecially as its saying "autoREconnect=false in the mysql dbPrperties section.
Could someone come up with a general purpose default dataSource definition suitable for mysql for a small number of users? I can tune the min/max active/idle etc, but is this not all done in tomcat, not grails?
"userServerPrepStmts=false" why would anyone want to disable prepared statements? We have been drilled for the last 15 years to only ever use prepared statements otherwise the DB cant cache them.
If I ignore all this complex example, and went with the super smiple one everyone posts, will it work properly? e.g. will it reconnect when the db goes down and up? will it not leak etc.
Thanks!

Answer 1

AFAIK, Tomcat has nothing to do with managing the database connection. Since Grails 2.3.6, these are the recommended default datasource properties:
properties {
//see http://grails.org/doc/latest/guide/conf.html#dataSource for documentation
jmxEnabled = true
initialSize = 5
maxActive = 50
minIdle = 5
maxIdle = 25
maxWait = 10000
maxAge = 10 * 60000
timeBetweenEvictionRunsMillis = 5000
minEvictableIdleTimeMillis = 60000
validationQuery = "SELECT 1"
validationQueryTimeout = 3
validationInterval = 15000
testOnBorrow = true
testWhileIdle = true
testOnReturn = false
jdbcInterceptors = "ConnectionState;StatementCache(max=200)"
defaultTransactionIsolation = java.sql.Connection.TRANSACTION_READ_COMMITTED
}