How exactly does the database connection pooling works ?

[shailesh.r.e]

I am using Spring ORM (2.5.6) with hibernate (3.3.2.GA). For the database connection pooling i have used c3p0 (0.9.1.2) with oracle 10g.

Can anyone explain me how exactly the connection pooling works ? As per my knowledge we cannot have a connection open for a long period of time. It's generally preferred to open a connection, do the transaction and then close it.

I was looking at the c3p0 implementation (com.mchange.v2.c3p0.ComboPooledDataSource). It uses the javax.sql.PooledConnection ?

Can anyone please explain how exactly is the PooledConnection implemented ?

Thanks in advance.

[dr_pompeii]

Hello Shailesh

Have read the documentation from the same C3P0 and its API?
it is not related with Spring itself

As per my knowledge we cannot have a connection open for a long period of time. It's generally preferred to open a connection, do the transaction and then close it.

Thats the reason to know how configure well many properties of C3P0, how idle, minimum and max connections etc

[shailesh.r.e]

Hi Dr_Pompeii,

Thanks for your response.

Yes, i know that the connection pooling (c3p0) is independent of spring.

I have also configured all the properties (max/min pool size, maxStatements, idle time, etc) for the connection pool.

My question was that though the configuration specifies a pool size and other details does it really maintain a live active connection pool (i.e implementation of the javax.sql.PooledConnection interface) or are the connections swapped when required.

If the connections are pooled and are active till the timeout period then what happens when the connection expires ?

Will the implementation swap a new connection to maintain the pool size or somehow recycle the expired connection object ?

Sorry, in case i am getting too much into the vendor specific implementation.

Thanks in advance.

[dr_pompeii]

Hello

My question was that though the configuration specifies a pool size and other details does it really maintain a live active connection pool (i.e implementation of the javax.sql.PooledConnection interface) or are the connections swapped when required.

is logic work with the JDBC API in the low/deeper level

If the connections are pooled and are active till the timeout period then what happens when the connection expires ?

I am not an expert, but I could assume that some exception could be throw or perhaps other connection from the pool could be re used

Will the implementation swap a new connection to maintain the pool size or somehow recycle the expired connection object ?

Could be

Sorry, in case i am getting too much into the vendor specific implementation.

Don't worry, but I suggest you friendly read the API, there should does mention about if some exception should be throw or not, BTW exists Forum for C3PO? If yes you can get some support there

HTH