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Idera SQL Workload Analysis computes the top SQL statements in terms of time spent in the database and the execution count from one source of such data in the system tables of SQL Server and correlates this with the execution count of that statement from another source (i.e another set of system tables in the SQL Server). Because of sampling rates, sampling errors and the transient nature of the latter source, the correlation is sometimes not possible for certain statements with very few executions in any given time frame.
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