Class B2IForwardScan

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.BTreeForwardScan

org.apache.derby.impl.store.access.btree.index.B2IForwardScan

All Implemented Interfaces:

ScanManager, GenericScanController, GroupFetchScanController, RowCountable, ScanController

public class B2IForwardScan
extends BTreeForwardScan

The btree secondary index implementation of ScanManager which provides reading and deleting of entries in the btree secondary index. This supports setting up and iterating through a set of rows while providing a start key, stop key, and a set of AND and OR qualifiers to skip unwanted rows. Currently derby only supports forward scans (but individual columns can have descending order). This interface is also used to delete rows from the conglomerate. Note that update is not supported, it must be implemented as a delete, followed by an insert. 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
private int	init_isolation_level

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
B2IForwardScan()

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, boolean hold, int open_mode, int lock_level, LockingPolicy locking_policy, int isolation_level, boolean open_for_locking, FormatableBitSet scanColumnList, DataValueDescriptor[] startKeyValue, int startSearchOperator, Qualifier[][] qualifier, DataValueDescriptor[] stopKeyValue, int stopSearchOperator, B2I conglomerate, B2IUndo undo, B2IStaticCompiledInfo static_info, DynamicCompiledOpenConglomInfo dynamic_info)	Initialize the scan for use.
ContainerHandle	reopen()	Open the container after it has been closed previously.

Methods inherited from class BTreeForwardScan

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, 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

init_isolation_level

private int init_isolation_level

Constructor Details

B2IForwardScan

B2IForwardScan()

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.

reopen

public ContainerHandle reopen()
                       throws StandardException

Open the container after it has been closed previously.

Open the container, obtaining necessary locks. Most work is actually done by RawStore.openContainer(). Will only reopen() if the container is not already open.

Overrides:

reopen in class OpenBTree

Throws:

StandardException - Standard exception policy.

init

public void init(TransactionManager xact_manager,
 Transaction rawtran,
 boolean hold,
 int open_mode,
 int lock_level,
 LockingPolicy locking_policy,
 int isolation_level,
 boolean open_for_locking,
 FormatableBitSet scanColumnList,
 DataValueDescriptor[] startKeyValue,
 int startSearchOperator,
 Qualifier[][] qualifier,
 DataValueDescriptor[] stopKeyValue,
 int stopSearchOperator,
 B2I conglomerate,
 B2IUndo undo,
 B2IStaticCompiledInfo static_info,
 DynamicCompiledOpenConglomInfo dynamic_info)
          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.