Class B2IMaxScan

java.lang.Object

org.apache.derby.impl.store.access.btree.OpenBTree

org.apache.derby.impl.store.access.btree.BTreeScan

org.apache.derby.impl.store.access.btree.BTreeMaxScan

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

Fields

Modifier and Type	Field	Description
private ConglomerateController	base_cc_for_locking

Fields inherited from class 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 OpenBTree

btree_undo, container, err_containerid, init_lock_level, init_open_user_scans, runtime_mem

Fields inherited from interface ScanController

GE, GT, NA

Constructor Summary

Constructors

Constructor	Description
B2IMaxScan()

Method Summary

Modifier and Type	Method	Description
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 BTreeMaxScan

fetchMax, fetchRows, positionAtStartPosition

Methods inherited from class BTreeScan

delete, didNotQualify, doesCurrentPositionQualify, fetch, fetchLocation, fetchNext, fetchNextGroup, fetchNextGroup, fetchSet, fetchWithoutQualify, getCurrentRecordHandleForDebugging, getScanInfo, init, isCurrentPositionDeleted, isHeldAfterCommit, isKeyed, newRowLocationTemplate, next, positionAtDoneScan, positionAtDoneScanFromClose, positionAtNextPage, positionAtPreviousPage, positionAtRowLocation, positionAtStartForForwardScan, process_qualifier, reopenScan, reopenScanByRowLocation, replace, reposition, toString

Methods inherited from class 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 Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface GenericScanController

isTableLocked

Methods inherited from interface RowCountable

getEstimatedRowCount, setEstimatedRowCount

Field Details

base_cc_for_locking

private ConglomerateController base_cc_for_locking

Constructor Details

B2IMaxScan

B2IMaxScan()

Method Details

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.