Class HeapScanInfo
- java.lang.Object
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- org.apache.derby.impl.store.access.heap.HeapScanInfo
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- All Implemented Interfaces:
ScanInfo
class HeapScanInfo 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().- See Also:
GenericScanController.getScanInfo()
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Field Summary
Fields Modifier and Type Field Description private int
stat_numColumnsFetched
private int
stat_numpages_visited
Performance counters ...private int
stat_numrows_qualified
private int
stat_numrows_visited
private FormatableBitSet
stat_validColumns
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Constructor Summary
Constructors Constructor Description HeapScanInfo(HeapScan scan)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description java.util.Properties
getAllScanInfo(java.util.Properties prop)
Return all information gathered about the scan.
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Field Detail
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stat_numpages_visited
private int stat_numpages_visited
Performance counters ...
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stat_numrows_visited
private int stat_numrows_visited
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stat_numrows_qualified
private int stat_numrows_qualified
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stat_numColumnsFetched
private int stat_numColumnsFetched
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stat_validColumns
private FormatableBitSet stat_validColumns
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Constructor Detail
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HeapScanInfo
HeapScanInfo(HeapScan scan)
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Method Detail
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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). NOTE - this list will be expanded as more information about the scan is gathered and returned.
- Specified by:
getAllScanInfo
in interfaceScanInfo
- Parameters:
prop
- Property list to fill in.- Throws:
StandardException
- Standard exception policy.
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