Being Cellfish

Stuff I wished I've found in some blog (and sometimes did)

August, 2013

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  • Being Cellfish

    Using triggers to protect your database from developers - still not a good idea


    A long time ago I mentioned that triggers is rarely a good option in your database. I recently read this article (requires free registration) that shows you a solution to prevent developers from updating a full table (or deleting it all) by mistake because they failed to ad a WHERE clause to their query. Is this a good reason to add triggers to your database? I think not! There are so many things wrong here in my opinion...

    First of all the script proposed the example have the same trigger duplicated three times (once for update, delete and update/delete triggers each) when that could have been avoided easily since the script is just building a string to run anyway. So from the start the script proposed could easily contain bugs depending on the type of trigger added.

    Second this is only protecting against the most simple mistakes where you forget your where clause. What if a query has a where clause like "WHERE ID > 1" (assuming there is at least one record not satisfying that condition. You are probably still miserable.

    I would still say that the use of stored procedures and proper security setup so that users can only execute stored procedures and not modify data is the solution. That way the stored procedure can be reviewed. Even checked automatically for things like always having a where clause. The stored procedure can also be tested with some unit tests. All that should be enough and better than adding triggers that gives you some false sense of protection. And remember your backups in the case you failed to catch something like this earlier. But that goes without saying whenever you work with a database I think.

  • Being Cellfish

    SQL server backup myths


    Any kind of backups other than straight file copies have Always been magic to me. Mostly because in the early years of my career it was so rare that the backups actually worked when needed because nobody evern tried the backups to see if they were actually working... This post (free registration needed to read) goes over some SQL server myths that are backup related. Way to many screen shots for my taste but interesting.

  • Being Cellfish

    Azure Websites and logs that are no longer updated


    Last weekend I helped my father-in-law (who is hosting his company web site on azure websites) troubleshoot why he was no longer getting any more data in the web server logs. Logs that he uses to analyze what content is popular. Well it turned out that you should read the FAQ... Once your logs reach 35MB, they are no longer updated until you clean up the directory. I guess it kind of makes sense because I did think that it was weird that you could just have any amount of logs for your website for free. But there is no free lunch I guess... I just wish the user interface where you turn this thing on would mention this in the little help popup because there are probably a lot of people out there that don't read the FAQ and just assumes the data will just be there...

    Also the logs didn't just start to magically appear due to some bug mentioned here. I had to change the size of the VM temporarily and then back in order to get the logs going again.

  • Being Cellfish

    Asynchronous enumerations - summary


    So what did we end up to do after the discussion two months ago? Well we ended up using option #1 mostly because it simplified things to have all items available during processing. technically not needed, but it simplified things.

    My generic advice would be to use option #1 or #2 and to favor option #2 whenever possible since #1 can easily be implemented wrapping #2. If your project is already heavy on using Rx, then and only then would I consider option #3.

    Here are the links to previous parts for your convenience:

  • Being Cellfish

    Asynchronous enumerations - Part 5: MyEnumerationAsync


    For background, read the introduction.

    If you have no need for filtering using LINQ (or Rx) and you do not want to expose an IEnumerable you can create tour own "IEnumeratorAsync" that asynchronously fetches the next item. Again this is something I would advice against. First of all you are loosing the option to use constructs like foreach since you do not use standard interfaces. Second you loose the option of using LINQ even for simple things.

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