> I don't think most storage engines actually compress the data Most major RDBMs (Oracle, MS SQL Server and even MySql) support page level compression. > bec

> I don't think most storage engines actually compress the data Most major RDBMs (Oracle, MS SQL Server and even MySql) support page level compression. > because it would slow down reads and writes dramatically Not really, modern compression algorithms (e.g. zippy) have much faster decompression/compression speed than IO speed even for SSD drives, and having smaller IO traffic due to data compression can make actual performance higher with compression. Also you can fit more compressed data into FS cache, which again reduces IO traffic. > Page-level compression might be useful, I guess, depending on your use case. Sure, here are some examples: http://sqlblog.com/blogs/linchi_shea/archive/2008/05/11/sql-server-2008-page-compression-compression-ratios-from-real-world-databases.aspx http://sqlblog.com/blogs/linchi_shea/archive/2008/05/11/sql-... and http://sqlblog.com/blogs/linchi_shea/archive/2008/05/16/sql-server-2008-page-compression-performance-impact-on-table-scans.aspx http://sqlblog.com/blogs/linchi_shea/archive/2008/05/16/sql-...