How to determine if java.sql.Connection is valid with PostgreSQL JDBC4

Question

I'm trying write a test for a method that returns a java.sql.Connection to connect to a PostgreSQL.

My test is very straightforward:

@Test
public void connectionFactoryShouldReturnOpenConnection() throws Exception {
    Connection conn = ConnectionFactory.getConnection();

    assertTrue(conn.isValid(2));
}

The isValid call fails, though:

org.postgresql.util.PSQLException: Method org.postgresql.jdbc4.Jdbc4Connection.isValid(int) is not yet implemented.
at org.postgresql.Driver.notImplemented(Driver.java:753)
at org.postgresql.jdbc4.AbstractJdbc4Connection.isValid(AbstractJdbc4Connection.java:109)
at org.postgresql.jdbc4.Jdbc4Connection.isValid(Jdbc4Connection.java:21)

What's going on? Surely there is a PostgreSQL JDBC driver that implements the methods of Java 1.6 such as isValid()?

Here the details on the driver I'm using:

<groupId>postgresql</groupId>
<artifactId>postgresql</artifactId>
<version>9.0-801.jdbc4</version>

I wonder if this is a case of: it didn't exist before 1.6, so all connection pool implementations support specifying a statement to execute to test the connection. Now since connection pools all support that, there isn't much demand for drivers that support the new method? Kind of perverse, but that's life. — araqnid
– araqnid, Commented Mar 11, 2011 at 23:28
@EricWilson - It appears that isValid() was implemented starting in version 9.2.1000 (released September 27, 2012) of the driver (I apologize for the double-notification) — Chris Forrence
– Chris Forrence, Commented May 1, 2013 at 22:50

Will Hartung · Accepted Answer · 2011-03-11 18:56:15Z

4

Perform a simple query, if it works, it's valid. If not, it's not.

And by simple query I mean something like:

SELECT 1;

Really simple.

answered Mar 11, 2011 at 18:56

Will Hartung

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3 Comments

Eric Wilson Over a year ago

If there is no other option, I'll go with that. But it doesn't make me confident in my driver to find such a simple method not implement.

basZero Over a year ago

bad idea, select 1 on a table with >2 mio rows becomes super slow... is there a way to disable this test connection thing at all?

Kaloyan Iliev Over a year ago

you use just "select 1" without any table. And this will return "1". Very quick query.

Kevin Manning · Accepted Answer · 2011-03-11 18:46:01Z

2

From the postresql driver source code the AbstractJdbc4Connection.isValid() throws this exception when called:

public boolean isValid(int timeout) throws SQLException
{
    checkClosed();
    throw org.postgresql.Driver.notImplemented(this.getClass(), "isValid(int)");
}

answered Mar 11, 2011 at 18:46

Kevin Manning

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1 Comment

Eric Wilson Over a year ago

That is interesting, and confirms my experience, but doesn't answer the question of how a connection can be best verified using Java JDBC and Postgres.

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