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

All Known Implementing Classes:
BTreeScanInfo, HeapScanInfo, Scan

public interface 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()

Method Summary
 java.util.Properties getAllScanInfo(java.util.Properties prop)
          Return all information gathered about the 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. These names have been internationalized, the names shown here are the old, non-internationalized names: scanType - type of the scan being performed: btree heap sort numPagesVisited - the number of pages visited during the scan. For btree scans this number only includes the leaf pages visited. numDeletedRowsVisited - the number of deleted rows visited during the scan. This number includes only those rows marked deleted. 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 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. columnsFetchedBitSet - The BitSet.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.

Parameters:
prop - Property list to fill in.
Throws:
StandardException - Standard exception policy.

Built on Tue 2006-10-10 19:23:47+0200, from revision exported

Apache Derby V10.1 Engine Documentation - Copyright © 1997,2005 The Apache Software Foundation or its licensors, as applicable.