How long should search companies hold on to user data? Google cut its storage time in half earlier this year. The EU wants to see no more than 6 months of data being held before it is tossed. Now, Yahoo has upped the ante, announcing it will only hold 3 months of user information. It makes for good headlines and PR and it’s certainly an attractive trend for all web privacy advocates, but for an industry based on data mining it’s hard to imagine all the precious data collected will simply be blanked.