Deeper Unity search indexing
Solution 1:
The Unity lens does not search all your files and folders, but rather only has access to files that you have opened at least once in the past (this is because it uses Zeitgeist for search).
There is a different lens you can install called "Unity Place Filesearch" which will search for every single file on your system. This provides much more thorough search results for files that you have never opened before. Once this new better search lens is installed, you can uninstall the old one if you do not want it anymore.
To install Unity Place Filesearch:
sudo add-apt-repository ppa:pydave/unity-lenses
sudo apt-get update
sudo apt-get install unity-place-filesearch
Then enter the following to make the lens appear:
setsid unity
OPTIONAL You can also set which folders to ignore (if you have private files) by editing the following file:
gedit ~/.filesearch.cfg
If you do edit this file, you can apply your changes by saving it then entering the following commands to stop and restart the lens.
killall unity-filesearch-daemon
setsid unity
To remove the old lens:
Backup the lens files first (just in case):
mkdir ~/backups
cp /usr/share/unity/places/files.place ~/backups/
Remove the lens:
sudo sed -i '14i ShowEntry=false' /usr/share/unity/places/files.place
And finally apply your changes by running:
unity --replace
All finished! Enjoy your new better search!
Sources all by Webupd8:
http://www.webupd8.org/2011/05/real-files-folders-search-unity-lens
http://www.webupd8.org/2011/04/things-to-tweak-fix-after-installing.html
Solution 2:
Dash is not a simple search tool, it correlates your usage of files and applications to link to your search results. It simply shows those files you previously opened.
Searching you should do with 'files and folders'. Then those files get added to dash.