Finally, I’ve updated the design of this site, to brand-new spanking HTML5, including a fluent layout, that adjusts for larger and smaller screens (it looks great on a phone too!). I created the previous design in 2005, so it was time for a refresh.
Just spend hours working out how to do this. If you’re moving pictures to another PC or your Picasa db gets broken, you may lose all your albums. The album information is stored alongside the Picasa database, in xml files with a .pal extension, which is irritating – you have to back up that folder too. Continue reading →
I’ve been thinking about backup solutions, and have been trying to find one that fits what I need. I have yet to find one, and this post is the first step in outlining what I need (and hopefully what other people need), with the end goal of building the perfect backup solution.
Quick note, I’ve uploaded some hi-res wallpapers on my photoblog site.
Right, back to work.
So, I’ve been playing around with Mono on a virtual machine for a while now, and want to just put down some thoughts. Note that this won’t be an in-depth review of Mono, but just my initial experiences coming from a MS .net background. Continue reading →
We’re distributing our .net application using Microsoft’s MSI installer technology (using the very powerful WiX to do it).
We’ve recently seen a problem with the installer not upgrading older versions, but rather just installing on top of the existing version, which results in the application being listed twice in the “Add/remove programs” (Programs and Features in Vista) section, one for each version. This results in weird things happening, like uninstalling one of them leaves the other one still installed with all the application files removed.
I ensured that we kept the same upgrade guid, with the version number incrementing, but all looked good. After searching and trying different things, I finally found this gem, hidden away in the MS documentation:
Note that Windows Installer uses only the first three fields of the product version. If you include a fourth field in your product version, the installer ignores the fourth field.
Why?!??
Our version numbers are in the order of 3.2.0.1234, 3.2.0.1456 (where the 4th number increments based on the Subversion revision number). The installer was seeing the version numbers as 3.2.0, i.e. the same, and not uninstalling the old version. Changing the installer version number to 3.2.1234 fixes this.
(this post is more a note to my future self than anything else)
The WP Super Cache plugin for WordPress is a pretty awesome plugin. The other day I was having problems with it not doing any caching and spitting out the following just before the head tag (where the wp_head() call is):
<!-- Page not cached by WP Super Cache. No closing HTML tag. Check your theme. -->
This was very odd. Everything I could find on the web regarding this problem was seeing this tag at the end of the html. Eventually I found a post that sounded similar to mine (and of course now I cannot find it again, unfortunately). It mentioned a plug-in using output buffering incorrectly. This makes sense, as looking in the source code of WP Super Cache, it outputs the message above in its output buffer handler if it cannot find a </html> closing tag. Needless to say, after a couple of hours fiddling, it turns out that it was a plug-in that I had written especially for the site, and it was doing exactly what the post mentioned (i.e. it was calling ob_end_flush() without calling ob_start()).
So it was all my fault, and I’ll probably do it in the future, hence this post!
So, note to self: If you see this in the future, check the plug-ins.
If you’re using SQL Server, and you’re inserting records into a table with an auto increment primary key, I suggest you don’t use @@IDENTITY to retrieve the previously inserted Id. Rather use SCOPE_IDENTITY().
The reason for this is that @@IDENTITY gives you the last generated Id in the current session vs. SCOPE_IDENTITY() gives you the last generated Id in the current scope.
The current session includes any triggers that run on the table after the insert. The current scope is just the current stored procedure that you’re in.
We were bitten by this recently. We were using @@IDENTITY when inserted into a table that is replicated. Upon insert the replication trigger was firing, inserting a record somewhere else. @@IDENTITY was giving us the identity of the record the trigger inserted.
Changing the @@IDENTITY to SCOPE_IDENTITY() fixed the problem.
This was even nastier in that by total fluke, the identity was matching a record that already existed, so when we used the retrieved identity to insert into another table, we didn’t violate the foreign key constraint.
Lesson learnt!
Update: I’ve found a page with an in-depth look at the different techniques. Its for SQL Server 2000, but applies to 2005/2008 too.
I’ve recently finished a new site for a client, and in the process of developing, I uploaded a test site to a web server for the client to review. Since going live with the actual site, I left the test site up and running (in the assumption that its less effort to leave it up than to take it down).
Unfortunately, google managed to find the test site and ranked it higher than the proper site for a couple of the keywords. Not good! Its a simple fix to put in a mod_rewrite redirect rule, but its quite incredible how quickly google managed to find a site that has no incoming links.
I have a feeling that its related to the site map plugin that we’re using for wordpress, I think that it pinged google when we were developing the site, and google happily went along and indexed the site.
So, if you’re developing a site, and put up a test version, make sure that you either take it down when making the site live, or ensure that it redirects to the correct site.
We’re using SQL Compact 3.5 in a smart client desktop application, talking to it with NHibernate and are experiencing performance problems in a couple of places.
In general, we’re very happy with the database, it is most of the time pretty fast, and easy to work with. The fact that it runs within our process also helps, as its easy to install and use. This is especially useful, as we are going to be running on relatively low-spec machines (laptops with 500MB ram).
We are however seeing a performance problem in SELECT statements with multiple joins (> 5).