initialPoolSize
Default: 3
minPoolSize
Default: 3
maxPoolSize
Default: 15
idleConnectionTestPeriod
Default: 0
If this is a number greater than 0, c3p0 will test all idle, pooled but unchecked-out connections, every this number of seconds.
maxIdleTime
Default: 0
Seconds a Connection can remain pooled but unused before being discarded. Zero means idle connections never expire.
maxStatements
Default: 0
The size of c3p0's PreparedStatement cache. Zero means statement caching is turned off.
propertyCycle
Default: 300
Maximum time in seconds before user configuration constraints are enforced. c3p0 enforces configuration constraints continually, and ignores this parameter. It is included for JDBC 3 completeness.
acquireIncrement
Default: 3
Determines how many connections at a time c3p0 will try to acquire when the pool is exhausted.
testConnectionOnCheckout
Default: false
Don't use. Very expensive. If true, an operation will be performed at every connection checkout to verify that the connection is valid. Better choice: verify connections periodically using c3p0.idleConnectionTestPeriod
autoCommitOnClose
Default: false
The JDBC spec is unforgivably silent on what should happen to unresolved, pending transactions on Connection close. C3P0's default policy is to rollback any uncommitted, pending work. (I think this is absolutely, undeniably the right policy, but there is no consensus among JDBC driver vendors.) Setting autoCommitOnClose to true causes uncommitted pending work to be committed, rather than rolled back on Connection close. [Note: Since the spec is absurdly unclear on this question, application authors who wish to avoid bugs and inconsistent behavior should ensure that all transactions are explicitly either committed or rolled-back before close is called.]
forceIgnoreUnresolvedTransactions
Default: false
Strongly disrecommended. Setting this to true may lead to subtle and bizarre bugs. This is a terrible setting, leave it alone unless absolutely necessary. It is here to workaround broken databases / JDBC drivers that do not properly support transactions, but that allow Connections' autoCommit flags to go to false regardless. If you are using a database that supports transactions "partially" (this is oxymoronic, as the whole point of transactions is to perform operations reliably and completely, but nonetheless such databases are out there), if you feel comfortable ignoring the fact that Connections with autoCommit == false may be in the middle of transactions and may hold locks and other resources, you may turn off c3p0's wise default behavior, which is to protect itself, as well as the usability and consistency of the database, by either rolling back (default) or committing (see c3p0.autoCommitOnClose above) unresolved transactions. This should only be set to true when you are sure you are using a database that allows Connections' autoCommit flag to go to false, but offers no other meaningful support of transactions. Otherwise setting this to true is just a bad idea.
numHelperThreads
Default: 3
c3p0 is very asynchronous. Slow JDBC operations are generally performed by helper threads that don't hold contended locks. Spreading these operations over multiple threads can significantly improve performance by allowing multiple operations to be performed simultaneously.
factoryClassLocation
Default: null
DataSources that will be bound by JNDI and use that API's Referenceable interface to store themselves may specify a URL from which the class capable of dereferencing a them may be loaded. If (as is usually the case) the c3p0 libraries will be locally available to the JNDI service, leave this set as null.