CeGetDiskFreeSpaceEx

This is one of the cases where you do have to dig into the SDK header files to find what you need. The CeGetDiskFreeSpaceEx RAPI function is not documented on my VS2005 MSDN, although you can easily find it on the online MSDN. I have to confess that I only found it after looking into the Windows Mobile 5 Pocket PC SDK rapi.h file. The online documentation says it is available since Windows CE 3.0, but a quick look at the same header file on the Pocket PC 2003 SDK is enough to see it is not there. So how do we decide who is right, the docs or the header? The answer is simple: use dynamic linking to the rapi.dll, and you will find out if this is supported or not.

During my furious searches on the net, I found an obscure thread posted by someone from Microsoft stating that this API is only exposed from ActiveSync versions 4.0 onwards.

Data Port Console 1.0 Beta 3 available for download

Right after uploading the Data Port Console Beta 3 (*), I decided to implement the TCP/IP sockets connectivity feature you could use in the old SQL CE Console. Extending the code was easy enough and I was able to do something that was impossible with the old code: connect to more than one PDA at the same time. This is going to enable some interesting scenarios where just one console will be able to manage mutiple PDAs connected to the desktop via a network. For GPRS scenarios this may need a mobile VPN to fix the device IP address. I've been thinking on how to go around it seems that the only way is to somehow revert the PDA and PC roles to a somewhat more "natural" way where the PC is the server and the PDA is the client, and not the other way around.

Next up is to enable the serial port connectivity for Bluetooth emulated COM ports (the code is there, just needs a little work). I would like to have a native Bluetooth connectivity option in order to make it simpler for users to set up their devices, but this will imply going back to my Bluetooth code (which I started to write for this very purpose...).

Where do I want to go last? Device P2P. In a few days I will start working on the DesktopSqlCe successor that will also run on devices, so your mobile applications will be able to consume SQL Compact Edition databases locally or on a nearby device.

Back to work.

(*) This is not a real Beta. I will keep adding features to the application while it is almost ready to go live and after that as well. Beta status will stop when data can be exported to an Access database and when the number of errors is reduced to a sane minimum.

Primary Key or Index? ROWGUIDCOL or Guid.NewGuid()?

If you are really worried about the performance of your SQL Compact Edition database, switch all your primary keys for unique indexes and always let the engine generate the UNIQUEINDENTIFIER's GUID value through the ROWGUIDCOL property - never ever use the Guid.NewGuid() function.

Looking for more performance material to publish about SQL Compact Edition, I found myself testing the performance of GUIDs when inserting on an indexed table. Performance will be marginally slower when you insert a GUID on a PRIMARY KEY column than when inserting it on a UNIQUE INDEX. In a 10,000 row insert sample it can be as low as half a second, but nevertheless this is an interesting result: PKs are slower.

Now, if you remove the ROWGUIDCOL property from the UNIQUEIDENTIFIER column and start generating the GUID values yourself, be prepared for a big surprise: the insertion time tripled (10.5 to 30.7 seconds on my battle-scarred JasJar). Is the Guid.NewGuid() function that slow?

Change MSI name in VS2005

Why can't we change the MSI file name on a VS2005 deployment project? When you create a deployment project with VS2005, the name of the resulting MSI file is the same as the project's name. From this point on, there is no way to change the output file name from the project properties (nor from anywhere else on the IDE, or is there?). Even if you rename the project on the Solution Explorer tree, the resulting MSI file name will not change.

The solution for this is to manually open the .vdproj file and edit it on a regular text editor (Notepad will do). Now search for the "OutputFilename" string under the configuration name of your choice (by default you will see "Debug" and "Release" under the "Configurations" group, but your project may have other configurations), and change the MSI file name. Save the file, open the project in VS2005 and rebuild.

Request for Orcas: can Microsoft please make this property available on the IDE?

EDIT: Someone smarter than me just showed me the way... Thanks, Pedro!

More troubles installing WTL Wizards in Vista

WTL 8.0 is out now so I decided to install it on my Vista box. Now that I know a bit more about Vista security, I launched a command window in Administrator mode in order to run all the setup scripts (desktop, Windows CE and Windows Mobile). All went smoothly.

Then I decided to install Sergey Solozhentsev's WTL Helper tool. No issues again (nice!). This great tool requires that you download and install a new WTL Wizard from Sergey's website. Instead for using a JScript file to install everything, Sergey's Wizard uses an MSI file, and this is when I felt the iron grip of Vista security again: the MSI just would not install reporting an error number 2739. My friend Google pointed me in the right direction, first to understand what this error means, and what to do about it.

For your information, I did not remove the JScript key but merely renamed it. Running the msiexec /i command from the admin command window did the rest of the trick.

Data Port Console 1.0 Beta 2 available for download

You can get the latest Beta 2 from this link. There are a number of bug fixes in this Beta that make it more stable and reliable. Error reporting has been improved but this requires that you update the device component using the included installer. As a matter of fact, users would be greeted with empty error dialogs because of how the OLE DB error information was being collected.

One of the features I added for this Beta was a special request of Alberto Silva: the ability to edit the query data grid (when the user enters an "updatable" SELECT). Behind the scenes, the code just uses a SqlCeCommandBuilder to create the necessary commands (displayed on the notes tab) and these are used for updating (use the save button). You can also filter the grid by selecting the row state and the changes can be rolled back row by row (before updating, of course).

Comments and suggestions are welcome!

Tuning SQL Compact Edition Insert Performance

Here's how you can improve on a good thing: speed up your bulk insertions in SQL Compact Edition up to 30%! Read all about it here.