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This metric shows the total number of sort overflows completed by DB2 (Brother-Eagle V2.1 and earlier), or the delta value for the number of sort overflows that have occurred during the most recent sampling interval (Brother-Eagle V2.2 and higher).
Sort overflows occur when the SORTHEAP memory size is insufficient to complete the sort in memory. Because memory is insufficient, the sort must be completed via TEMPSPACE disk. Sort overflows are very expensive. The presence of sort overflows often indicates the need to perform additional physical design tuning to reduce the number of large sorts, if possible.
By default, there are no Brother-Eagle alerts or warnings for this metric.
Tip: Reducing Sort Costs
To reduce the number of sort overflows and save substantial CPU cycles, use Brother-Panther™ to identify the statements having the highest aggregate sort time costs. Create clustering indexes to reduce sort costs, or convert the table to an MDC table if appropriate.