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Load List Values for Improved Efficiency

Posted by Hemos on from the leaner-and-meaner dept.

An anonymous reader writes "Reduce the number of database hits and improve your Web application's efficiency when you load common shared list values only once. In this code-filled article, learn to load the values for drop-down lists when your Web application starts and then to share these loaded list values among all the users of your application."

7 of 207 comments (clear)

  1. Changes to the lists? by saundo · · Score: 5, Insightful

    Interesting article, but preloading those values will invariably lead to out of sync conditions when the backend changes. Nothing mentioned in the text as to how to cater for that eventuality.

    --
    -- The problem with troubleshooting is that sometimes trouble shoots back.
  2. Huh? by Renegade+Lisp · · Score: 5, Insightful
    Sorry I don't get it. Of course, when you load your data from a cache in main memory, even from within the same address space, you are several orders of magnitude faster than if you make the trip to the database each time. And by several orders of magnitude I mean six to seven orders: you'll easily be a million times faster for a given operation. (A database roundtrip is on the order of tens of milliseconds, while a lookup in a Java hashtable takes mere nanoseconds on typical hardware.)

    What's the point? Since when is Slashdot a forum for random tech tips (and not very thrilling ones at that)? Did IBM pay to get this posted? Is Slashdot trying to make fun of IBM by actually posting it?

    1. Re:Huh? by computational+super · · Score: 5, Insightful

      I think you're being FAR too polite here, sir. Feel free to drop in an occasional, "Are you f-ing kidding me with this drivel?" in your critique of this type of ridiculously simplistic and obvious article.

      On the other hand, there's a good take-away here. If this "revolutionary technique" was so mind-bending to IBM consulting services, I know where I won't be spending my consulting dollars...

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      Proud neuron in the Slashdot hivemind since 2002.
  3. Slow news day? Christ. by Electroly · · Score: 5, Insightful

    This just in! Caching frequently-used data yields performance improvements! Film at 11!

  4. Done this for years by Ckwop · · Score: 5, Insightful

    Well thank you captain obvious.. I've been doing this for years with ASP. Just load the contents of the listboxes into the Application object.

    In ASP.NET you can even do cache invalidation when the database changes. Simply create an extended stored procedure that's fired when any of you update/insert producers run that write to the changed record ids to a Queue (using Microsoft's Messaging and Queuing service) then have a thread in the ASP.NET process that periodically check the queue for new messages and clear the values that have changed out of the cache.

    Because the Queuing service works across networks it's a really neat way to provide scalabity in web applications - if you can't wait for SQL 2005 which will provide cache invalidation on database updates as standard.

    Simon.

  5. Is This Consultant on YOUR Payroll? by rimu+guy · · Score: 5, Informative

    If you have yet to read the 25-page FA, may I present the precis:

    Database hits are expensive. Reduce them where possible. For example, cache static lookup data.

    The simplicity of the point however is lost in the complexity of the article. It covers web.xml settings, servlet classes, list value loaders, persistence backends for said loaders, data source 'helpers' for said loaders, custom object classes for the loaders, several subclasses for said object classes, and a jsp page (to boot). Phew.

    The author refers to this design as a quick and easy approach. It is not. If you are not familiar with Java and read this article, please do not be put off. He could have demonstrated the point with a far simpler example. E.g. static variable, sql statement, jsp code, done.

    [The author] has worked with IBM Global Services for one year, and has five years of experience in J2EE-related technologies. And it shows. I dread to think how much a fully realized IBM Global Services project would cost should all its consultants apply this sized sledgehammer to each small task. Hopefully the article was not written up on the client's dime as well.

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    Java Hosting

  6. And for the follow-up article... by azuroff · · Score: 5, Funny

    ...this "Lead Developer" at IBM will discover the wonderful performance benefits of pooling database connections, rather than open a new connection every single fricking time he hits the database. No wonder he saw a massive performance increase when he learned how to cache the lookup values.

    And what's up with the "obj_" prefixes in some of the code listings? Newsflash: Java is an object-oriented programming language, and most competent Java programmers can figure out that a variable called resultSet probably isn't a primitive. You don't need to waste another 4 characters pointing out that fact.