Missing SQL statistics when monitoring SQL Server 2005

Ignite PI collects SQL execution statistics when monitoring SQL Server 2005 and above.  In certain cases, some SQL statements may be missing SQL execution statistics.   This may be due to:

1. SQL statistics collections as been turned off entirely for the monitored database instance (Options -> Advanced Options -> Support Options -> Monitored Database Instance Options -> ENABLE_SQLSTATS).

2. The SQL buffer cache on the monitored database is too small and/or too many distinct SQL statements are getting executed on the monitored database.    SQL statistics are queried every 10 minutes and compared to the previously queried values; if the same SQL statement cannot be found in the buffer cache after 10 minutes, no SQL statistics can be calculated for that SQL statement.

3. The SQL statement is contained within a stored procedure that has been compiled with the RECOMPILE option, or the SQL statement uses the RECOMPILE query hint.  This causes SQL server to recompile the stored procedure (or statement) before every execution and to not store the SQL plan in the buffer cache.  If the SQL plan for the statement is not stored in the buffer cache, SQL Server does not track SQL statistics for that statement.