org.apache.derby.impl.store.access.btree
Class BTreeScanInfo

java.lang.Object
  extended by org.apache.derby.impl.store.access.btree.BTreeScanInfo
All Implemented Interfaces:
ScanInfo

 class BTreeScanInfo
extends java.lang.Object
implements ScanInfo

This object provides performance information related to an open scan. The information is accumulated during operations on a ScanController() and then copied into this object and returned by a call to ScanController.getStatistic().


Field Summary
private  int stat_numColumnsFetched
           
private  int stat_numdeleted_rows_visited
           
private  int stat_numpages_visited
          Performance counters ...
private  int stat_numrows_qualified
           
private  int stat_numrows_visited
           
private  int stat_treeHeight
           
private  FormatableBitSet stat_validColumns
           
 
Constructor Summary
BTreeScanInfo(BTreeScan scan)
           
 
Method Summary
 java.util.Properties getAllScanInfo(java.util.Properties prop)
          Return all information gathered about the scan.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

stat_numpages_visited

private int stat_numpages_visited
Performance counters ...


stat_numrows_visited

private int stat_numrows_visited

stat_numrows_qualified

private int stat_numrows_qualified

stat_numdeleted_rows_visited

private int stat_numdeleted_rows_visited

stat_numColumnsFetched

private int stat_numColumnsFetched

stat_treeHeight

private int stat_treeHeight

stat_validColumns

private FormatableBitSet stat_validColumns
Constructor Detail

BTreeScanInfo

BTreeScanInfo(BTreeScan scan)
Method Detail

getAllScanInfo

public java.util.Properties getAllScanInfo(java.util.Properties prop)
                                    throws StandardException
Return all information gathered about the scan.

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

Not all scans 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: numPagesVisited - the number of pages visited during the scan. For btree scans this number only includes the leaf pages visited. numRowsVisited - the number of rows visited during the scan. This number includes all rows, including: those marked deleted, those that don't meet qualification, ... numRowsQualified - the number of undeleted rows, which met the qualification. treeHeight (btree's only) - for btree's the height of the tree. A tree with one page has a height of 1. Total number of pages visited in a btree scan is (treeHeight - 1 + numPagesVisited). numColumnsFetched - the number of columns Fetched - partial scans will result in fetching less columns than the total number in the scan. columnsFetched - The FormatableBitSet.toString() method called on the validColumns arg. to the scan, unless validColumns was set to null, and in that case we will return "all". NOTE - this list will be expanded as more information about the scan is gathered and returned.

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

Built on Thu 2012-03-29 21:53:33+0000, from revision ???

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