If your goal is write-once archival and subsequent query of large volumes of data, e.g., log/event data, you can't do much better than some of the column-oriented databases.  Two examples are SenSage and Vertica.<p>See customer profiles for SenSage at <a href="http://sensage.com/customers/customer-profiles.php" rel="nofollow">http://sensage.com/customers/customer-profiles.php</a>.  Various customers collect and store up to 200GB of raw text log files (400 million records at generous 500bytes/line estimate) broken into records ... PER DAY ...  with 2 to 5 or even more years of data online available for analysis ... fast analysis ... one example is an 8-billion-record query in 2 minutes.