are the management views actually reliable?

Nov 15, 2007 at 9:40 AM
I have a question concerning the data held within the views - how reliable is it and what are the criteria for what is displayed - for example sys.dmdbindexusagestats - I've collected data from this view at regualr intervals - my database has around 7000 indexes on tables which have data in the table - over a 71 day period I only have data for just under 1,500 indexes from the view - what about the other 5,500 indexes ? I'm a bit pushed to really know where to direct this type of question - dmvstats and the performance dashboard make extensive use of the dmv's - but are the dmv's actually representative of my database usuage/performance?
Jan 2, 2008 at 3:54 PM
I use the DMV sys.dmdbindexusagestats and as far as I see all used indexes are recorded. The DMV's are cleared when you restart the server. So you have to make a snanpshot of sys.dmdbindexusagestats just before you shut down the server.

You also have to keep in mind that maybe not every process runs in 71 days. In this case a longer period would be needed to see all used indexes.