org.apache.derby.impl.store.access.btree.index
Class B2IMaxScan

java.lang.Object
  extended by org.apache.derby.impl.store.access.btree.OpenBTree
      extended by org.apache.derby.impl.store.access.btree.BTreeScan
          extended by org.apache.derby.impl.store.access.btree.BTreeMaxScan
              extended by org.apache.derby.impl.store.access.btree.index.B2IMaxScan
All Implemented Interfaces:
ScanManager, GenericScanController, GroupFetchScanController, RowCountable, ScanController

public class B2IMaxScan
extends BTreeMaxScan

Scan used to find maximum value in the secondary index. This class implements an optimized interface to find the maximum row, for a set of rows between an input start and stop key. Note most work of this class is inherited from the generic btree implementation. This class initializes the top level object and deals with locking information specific to a secondary index implementation of a btree.


Field Summary
private  ConglomerateController base_cc_for_locking
           
 
Fields inherited from class org.apache.derby.impl.store.access.btree.BTreeScan
fetchNext_one_slot_array, init_fetchDesc, init_forUpdate, init_hold, init_lock_fetch_desc, init_qualifier, init_rawtran, init_scanColumnList, init_startKeyValue, init_startSearchOperator, init_stopKeyValue, init_stopSearchOperator, init_template, init_useUpdateLocks, lock_operation, SCAN_DONE, SCAN_HOLD_INIT, SCAN_HOLD_INPROGRESS, SCAN_INIT, SCAN_INPROGRESS, scan_state, stat_numdeleted_rows_visited, stat_numpages_visited, stat_numrows_qualified, stat_numrows_visited
 
Fields inherited from class org.apache.derby.impl.store.access.btree.OpenBTree
btree_undo, container, err_containerid, init_lock_level, init_open_user_scans, runtime_mem
 
Fields inherited from interface org.apache.derby.iapi.store.access.ScanController
GE, GT, NA
 
Constructor Summary
B2IMaxScan()
           
 
Method Summary
 void close()
          Close the scan.
 boolean closeForEndTransaction(boolean closeHeldScan)
          Close the scan, a commit or abort is about to happen.
 void init(TransactionManager xact_manager, Transaction rawtran, int open_mode, int lock_level, LockingPolicy locking_policy, int isolation_level, boolean open_for_locking, FormatableBitSet scanColumnList, B2I conglomerate, B2IUndo undo)
          Initialize the scan for use.
 
Methods inherited from class org.apache.derby.impl.store.access.btree.BTreeMaxScan
fetchMax, fetchRows, positionAtStartPosition
 
Methods inherited from class org.apache.derby.impl.store.access.btree.BTreeScan
delete, didNotQualify, doesCurrentPositionQualify, fetch, fetchLocation, fetchNext, fetchNextGroup, fetchNextGroup, fetchSet, fetchWithoutQualify, getCurrentRecordHandleForDebugging, getScanInfo, init, isCurrentPositionDeleted, isHeldAfterCommit, isKeyed, newRowLocationTemplate, next, positionAtDoneScan, positionAtDoneScanFromClose, positionAtNextPage, positionAtRowLocation, positionAtStartForForwardScan, process_qualifier, reopenScan, reopenScanByRowLocation, replace, reposition, toString
 
Methods inherited from class org.apache.derby.impl.store.access.btree.OpenBTree
checkConsistency, debugConglomerate, getColumnSortOrderInfo, getConglomerate, getContainer, getContainerHandle, getEstimatedRowCount, getHeight, getHold, getLockingPolicy, getLockLevel, getOpenMode, getRawTran, getRuntimeMem, getSpaceInfo, getXactMgr, init, isClosed, isTableLocked, reopen, setEstimatedRowCount, setLockingPolicy, test_errors
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface org.apache.derby.iapi.store.access.GenericScanController
isTableLocked
 
Methods inherited from interface org.apache.derby.iapi.store.access.RowCountable
getEstimatedRowCount, setEstimatedRowCount
 

Field Detail

base_cc_for_locking

private ConglomerateController base_cc_for_locking
Constructor Detail

B2IMaxScan

B2IMaxScan()
Method Detail

close

public void close()
           throws StandardException
Close the scan.

Specified by:
close in interface GenericScanController
Overrides:
close in class BTreeScan
Throws:
StandardException - Standard exception policy.
See Also:
GenericScanController.newRowLocationTemplate()

closeForEndTransaction

public boolean closeForEndTransaction(boolean closeHeldScan)
                               throws StandardException
Close the scan, a commit or abort is about to happen.

Specified by:
closeForEndTransaction in interface ScanManager
Overrides:
closeForEndTransaction in class BTreeScan
Parameters:
closeHeldScan - If true, means to close scan even if it has been opened to be kept opened across commit. This is used to close these scans on abort.
Returns:
boolean indicating that the close has resulted in a real close of the scan. A held scan will return false if called by closeForEndTransaction(false), otherwise it will return true. A non-held scan will always return true.
Throws:
StandardException - Standard exception policy.

init

public void init(TransactionManager xact_manager,
                 Transaction rawtran,
                 int open_mode,
                 int lock_level,
                 LockingPolicy locking_policy,
                 int isolation_level,
                 boolean open_for_locking,
                 FormatableBitSet scanColumnList,
                 B2I conglomerate,
                 B2IUndo undo)
          throws StandardException
Initialize the scan for use.

Any changes to this method may have to be reflected in close as well.

The btree init opens the container (super.init), and stores away the state of the qualifiers. The actual searching for the first position is delayed until the first next() call.

Throws:
StandardException - Standard exception policy.

Built on Thu 2010-12-23 20:49:13+0000, from revision ???

Apache Derby V10.6 Internals - Copyright © 2004,2007 The Apache Software Foundation. All Rights Reserved.