Re: Tomcat JDBC Connection Pool interfaces to PostgreSQL...

This appears to be another incident of a report received a couple of weeks
ago...

http://www.postgresql.org/message-id/1462213750076-5901531.post@n5.nabble.com

David J.

On Tue, May 17, 2016 at 4:17 PM, Dave Cramer <pg(at)fastcrypt(dot)com> wrote:

> it would appear that tomcat is not returning the PgConnection object.
>
> I just wrote this as a test:
>
> public void testConnectionUnwrapPGDataSource() throws SQLException {
> PGSimpleDataSource dataSource = new PGSimpleDataSource();
> assertNotNull(dataSource);
> dataSource.setDatabaseName("test");
> dataSource.setServerName("localhost");
> dataSource.setPortNumber(5432);
> Connection connection = dataSource.getConnection("test","test");
> assertNotNull(connection);
> Object v=connection.unwrap(PGConnection.class);
> assertNotNull(v);
> assertTrue(v instanceof PGConnection);
>
> }
>
> and it works fine.
>
>
> Dave Cramer
>
> davec(at)postgresintl(dot)com
> www.postgresintl.com
>
> On 17 May 2016 at 14:40, Eric Neron <eneron(at)e-djuster(dot)ca> wrote:
>
>> I am currently working using the Tomcat JDBC Connection Pool (
>> http://tomcat.apache.org/tomcat-7.0-doc/jdbc-pool.html) which we plan to
>> use in our Java Web application in order to streamline server resources
>> usage associated to supporting our PostgreSQL connections (i.e.,
>> minimize the number or connections required).
>>
>> I am using the following jar files to support my work:
>>
>> tomcat-jdbc.jar
>> postgresql-9.4.1208.jre7.jar
>>
>> Although most of it seems to be working fine so far, I am hitting issues
>> when I try to "cast" the connection the pool is returning to me (a
>> ProxyConnection) into either a PGConnection or BaseConnection. I need
>> those in order to access either of the following PostgreSQL
>> "advanced/internal" methods:
>>
>> - addDataType () (PGConnection)
>> - CopyManager () (BaseConnection).
>>
>> The Tomcat documentation suggests to extract the native connection by
>> using the following method:
>>
>> Connection pgConnection = ((javax.sql.PooledConnection) conn).
>> getConnection ( );
>>
>> Although this does not fail, using a debugger, I can see that
>> pgConnection is really an
>> org.postgresql.jdbc.PgConnection (not an org.postgresql.PGConnection),
>> and there is not way it seems that I can bridge between the two... even by
>> using:
>>
>> pgConnection.unwrap ( PGConnection.class );
>>
>> I am just wondering if this issue is caused by the fact that I use the
>>
>> org.apache.tomcat.jdbc.pool.DataSource to instantiate my Connection Pool.
>>
>> Browsing through the list of choice given to me to determine where
>> the DataSource class is imported in my Java code, I can see:
>>
>> javax.sql.DataSource (which I have seen can give one access to
>> PGConnection from one of my research on the Web - http://stackoverflow
>> .com/questions/27898632/how-to-cast-jdbc4connection-to-pgconnection),
>> though if I select it, it tells me that this is an abstract Class that I
>> cannot instantiate from!
>>
>> Similarly, another StackOverlflow page (http://stackoverflow
>> .com/questions/36986653/cast-java-sql-connection-to-pgconnection)
>> suggests using the following code:
>>
>> PGConnection pgConnection = dataSource.getConnection().unwrap(PGConnection.class);
>>
>> but again, if I try this, I get the following SQLException: "Not a wrapper of org.postgresql.PGConnection"
>>
>> (in fact, it turns out that this is exactly the same solution as the "Tomcat solution" I explained above).
>>
>> I am running out of alternatives... Any ideas?
>>
>>
>>
>>
>>
>>
>>
>