Java Enterprise Best Practices

Avoid Type 1 and Type 3 Drivers

Sun classifies JDBC drivers into four categories, as shown in Table 4-1.

Table 4-1. JDBC drivers

Driver	Description
Type 1	A bridge between JDBC and another database-independent API, such as ODBC. The JDBC-ODBC driver that comes with the Java SDK is the primary example of a Type 1 driver.
Type 2	Translates JDBC calls into native API calls provided by the database vendor.
Type 3	Network bridges that enable an application to take advantage of the WORA (write once, run anywhere) capabilities of Type 4 drivers, even when your database of choice supports only Type 2 drivers.
Type 4	Talks directly to a database using a network protocol. Because it makes no native calls, it can run on any Java Virtual Machine (JVM).

Most programmers learn JDBC using the JDBC-ODBC Bridge, which is a Type 1 JDBC driver. Nevertheless, the JDBC-ODBC Bridge is a bridging driver. In other words, it’s a driver that falls into the Type 1 or Type 3 categories. These types of drivers provide much weaker database performance than direct access drivers, and the reason for the weakness is fairly simple: bridging technologies require more hops to communicate with the database.

Though avoiding Type 1 and Type 3 drivers is a good rule of thumb, sometimes they cannot be avoided. Not all databases are supported by a Type 2 or Type 4 driver. For example, if you want an application to talk to Microsoft Access, you must use a Type 1 or Type 3 driver.

When to use a Type 1 or Type 3 driver ...