IBM Books

Sort Overflows


Snapshot Information Level
Database
Application

API Structure(s)
sqlm_dbase
sqlm_appl
sqlm_stmt

Monitor Group
Sort
Sort
Sort

Resettable

Yes

 

Event Information Level
Database
Connection
Statement

API Structure(s)
sqlm_db_event
sqlm_conn_event
sqlm_stmt_event

 

API Element Name
Element Type

sort_overflows
counter

 

Description:  The total number of sorts that ran out of sort heap and may have required disk space for temporary storage.

Usage:  At a database or application level, use this element in conjunction with "Total Sorts" to calculate the percentage of sorts that had to overflow to disk. If this percentage is high, you may want adjust the database configuration by increasing the value of sortheap.

At a statement level, use this element to identify statements that require large sorts. These statements may benefit from additional tuning to reduce the amount of sorting required.

When a sort overflows, additional overhead will be incurred because the sort will require a merge phase and can potentially require more I/O, if data needs to be written to disk.

This element provides information for one statement, one application, or all applications accessing one database.

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