Gail,

My tests have shown a performance degradation when the same queries run on compressed tables compared to uncompressed.

I know, there are fewer pages to trawl across, but it is more expensive to crack them open as well - I've found the net effect to be negative (10-20% give or take).

Especially with page compression, even if you have 1/3 of the pages (typical for many data tables) I've found it to still be quicker when having compression off. Looks like the access speed of each page goes down by a bit more than the size reduction.

If there are exceptions to this I'd love to hear them, so I can fine-tune the algorithms.:cool: