org.apache.derby.impl.store.access.btree
Class BTreeScanInfo
java.lang.Object
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().
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 |
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
BTreeScanInfo
BTreeScanInfo(BTreeScan scan)
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.
Apache Derby V10.6 Internals - Copyright © 2004,2007 The Apache Software Foundation. All Rights Reserved.