Question - how well does the query parser handle stale queries? SQL Server for the longest time had issues with plan stability in that the plan became too stable. When the data distribution changed dramatically, the queries didn't age out of the cache and the queries would do such things as use the wrong index, or not work out the correct cardinality of a table and then use an index where really a full table scan would have been better... and so on.
To clarify - if you add the query hint, run the query, then remove the query hint then has the original query's plan expired?
Edit: I know I'm asking a lot about the plan cache, but as it's a core selling point, then I'd like to know how data distribution changes will affect performance. Stale queries will potentially adversley affect performance under certain circumstances.