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Message Posted: Mon, 29 Jan 2007 @ 10:42:33 GMT

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Hi Bill,

Are you experiencing particular problems or just curious?

Here are a couple of thoughts in response to your questions.

The main difference between the different "types" of JDBC driver is the way the driver is constructed under the covers. In a nutshell, the type 4 driver communicates directly with the database. The type 3 driver communicates with the database via an agent (jserver?) which must be running somewhere in the network. For what it is worth there is also a Type 1 driver which translates JDBC calls into ODBC calls and a Type 2 driver which I can't recall how it is architected.

In answer to your jserver question, it has been a very long time I've looked at the Type 3 driver so I'm assuming this is the gateway program. If my assumption is correct, there is no upgrade to this program as it is obsolete in the Type 4 architecture.

Generally, the Type 4 driver is the best driver to use and this is true in Teradata. In Teradata, the Type 4 driver has vastly superior performance over all the other types. It is also more complete than the Type 3 driver.

In terms of compatibility for programs using the driver, there are two issues to consider.

First, each "type" of driver still has to implement all of the methods defined by the java.sql.* interfaces. These are the methods that you call to establish sessions, submit queries, retrieve results and so on. In each Type of driver the method has the same signature, so a program written for the JDBC Type 3 driver should work with Type 4.

The second issue is how the driver actually works. Put simply does method X do the same thing in both types of driver. In general terms the answer is yes, they do. However, it is possible that there are some nuances enhancements, bug fixes or whatever that might have an affect on your software. Obviously testing is critical.

The JDBC driver has come along way since the V2R3 days. You (or the programmer dude/dudette) may have noticed with the Type 3 has a number of methods that simply throw an Unsupported Exception. Most, if not all of these, actually do something useful now.

For what it is worth, a number of command line, Windows (Swing) and Web applications that I built on the Type 3 driver converted to the Type 4 driver with little or no effort.

I hope this helps

Glenn Mc

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