7-Zip, drag and drop and the temp-dir mystery
Today I downloaded the Eclipse Ganymede M6 Java EE package. It is a 178MB ZIP archive containing the IDE. Downloading took a few minutes and then I was ready to go. Well, almost. Of course the ZIP needed to be extracted first. I use 7-Zip as the archive tool of choice. It has proven to be reliable and fast.
However it shares one "habit" I have seen so far with every archive tool I tried: Wherever you want to extract the contents of the archive, it will first put all files into the %temp% directory - often on the system partition - and only then copy the unpacked content to the final location.
With the Ganymede package this means 217MB of data in 4180 files and folders are first read from the archive and stored in a folder. On my P4@3GHz this takes about 110s. After that a copy of that some data - almost 4200 files - takes another 90s. Apart from that, instead of 217MB I now need twice as much almost half a gigabyte to store both the temp copy and the final one. Why is that necessary?
There are some threads on the 7-Zip forum also discussing this. Apparently (however I could not find it in the linked MSDN articles) this has to do with how Windows handles drag and drop. And indeed, extracting via the "two-folder mode" (F9 in 7-Zip, I did not know that before) puts the archive contents directly to the destination, saving almost half the time.
If anyone more knowledgeable in Windows development could shed some light on this, I would surely be grateful. For now, knowing the workaround is fine, too.
Just one more thing: When I first hit F9 in a 7-Zip window apparently nothing happened. Turns out the split control was all the way to the left, almost invisible next to the window border, so if you don't see a second pane come up, have a close look there :)