Strange executing batch

Hi , pgsql-jdbc.

 How jdbc driver works with batch in one transaction all added
 statement  or  each statement in individual transaction?

Class.forName("org.postgresql.Driver");

Connection c = DriverManager.getConnection("jdbc:postgresql:....");

PreparedStatement p = c.prepareStatement("insert into test(test) values(?)");
c.setAutoCommit(false);
for (int i = 0; i < 1000; i++) {
 p.setString(1, "test"+i);
 p.addBatch();
}

p.executeBatch();

If at executing executeBatch() on 500 statement error is arised ,that
for some reason first 499 statement are  committed.

--
Truly yours,
 Ilya                          mailto:i_il@mail.ru