Package org.apache.derby.impl.store.access.sort

Class MergeSortInfo

  • All Implemented Interfaces:
    SortInfo
    class MergeSortInfo
extends java.lang.Object
implements 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().
    See Also:
    SortController.getSortInfo()

    • Field Detail

      • stat_sortType

        private java.lang.String stat_sortType
        Performance counters ...

      • stat_numRowsInput

        private int stat_numRowsInput

      • stat_numRowsOutput

        private int stat_numRowsOutput

      • stat_numMergeRuns

        private int stat_numMergeRuns

      • stat_mergeRunsSize

        private java.util.Vector stat_mergeRunsSize

    • Method Detail

      • getAllSortInfo

        public java.util.Properties getAllSortInfo​(java.util.Properties prop)
                                    throws 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.

        Specified by:
        getAllSortInfo in interface SortInfo
        Parameters:
        prop - Property list to fill in.
        Throws:
        StandardException - Standard exception policy.