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org.apache.derby.iapi.store.access
Interface SortInfo

public interface SortInfo

This object provides performance information related to a sort. The information is accumulated during operations on a SortController() and then copied into this object and returned by a call to SortController.getSortInfo().

Method Summary

java.util.Properties getAllSortInfo(java.util.Properties prop)
Return all information gathered about the sort.

Method Detail

getAllSortInfo

public java.util.Properties getAllSortInfo(java.util.Properties prop)
                                    throws org.apache.derby.iapi.error.StandardException

Return all information gathered about the sort.

This routine returns a list of properties which contains all information gathered about the sort. If a Property is passed in, then that property list is appended to, otherwise a new property object is created and returned.

Not all sorts may support all properties, if the property is not supported then it will not be returned. The following is a list of properties that may be returned: sortType - type of the sort being performed: internal external numRowsInput - the number of rows input to the sort. This number includes duplicates. numRowsOutput - the number of rows to be output by the sort. This number may be different from numRowsInput since duplicates may not be output. numMergeRuns - the number of merge runs for the sort. Applicable to external sorts only. Note: when a SortController is closed, numMergeRuns may increase by 1, to reflect the additional merge run that may be created for any data still in the sort buffer. mergeRunsSize - the size (number of rows) of each merge run for the sort. Applicable to external sorts only. e.g. [3,3,2] indicates 3 merge runs, where the first two runs have 3 rows each, and the last run has 2 rows. Note: when a SortController is closed, this vector may get an additional element, to reflect the additional merge run that may be created for any data still in the sort buffer. NOTE - this list will be expanded as more information about the sort is gathered and returned.