com.bigdata.btree.ITupleCursor2 Maven / Gradle / Ivy
/*
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
[email protected]
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* Created on Aug 9, 2008
*/
package com.bigdata.btree;
/**
* Extended interface.
*
* When {@link #first()}, {@link #last()}, or
* {@link ITupleCursor#seek(byte[])} return null it is an
* indication that there is no visitable tuple in the index corresponding to
* that request. Likewise {@link #tuple()} will return null if
* the cursor position does not correspond to a tuple in the index or if the
* tuple at that cursor position has since been deleted.
*
* @author Bryan Thompson
* @version $Id$
*/
public interface ITupleCursor2 extends ITupleCursor {
/**
* The optional inclusive lower bound imposed by the {@link ITupleCursor}.
*/
byte[] getFromKey();
/**
* The optional exclusive upper bound imposed by the {@link ITupleCursor}.
*/
byte[] getToKey();
/**
* Return true if the cursor is willing to visit deleted
* tuples. In order to observe deleted tuples the index must have been
* provisioned with support for delete markers enabled.
*
* Note: When delete markers are enabled in the index and a tuple is
* deleted, the tuple is NOT removed from the index. Instead a "delete"
* marker is set and the value associated with the key is cleared to
* null.
*
* @see IndexMetadata#getDeleteMarkers()
*/
public boolean isDeletedTupleVisitor();
/**
* Return true if the cursor position is defined.
*
* Note: Use {@link #currentKey()} to obtain the key corresponding to the
* current cursor position and {@link #tuple()} to obtain the visitable
* tuple in the index corresponding to that cursor position (if any).
*/
boolean isCursorPositionDefined();
/**
* Return the key corresponding to the current cursor position (even if
* there is no tuple in the index for that key).
*
* @return The key corresponding to the current current position -or-
* null iff the cursor position is undefined.
*/
byte[] currentKey();
/**
* Position the cursor on the first visitable tuple in the natural index
* order for the index or index partition over which the cursor is defined.
* If there are no visitable tuples then the cursor position will be
* undefined.
*
* @return The current tuple -or- null iff there is no
* visitable tuple corresponding to the current cursor position.
*/
ITuple first();
/**
* Position the cursor on the last visitable tuple in the natural index
* order for the index or index partition over which the cursor is defined.
* If there are no visitable tuples then the cursor position will be
* undefined.
*
* @return true if the cursor was positioned on a tuple.
*/
ITuple last();
/**
* The tuple reflecting the data in the index at the current cursor
* position.
*
* @return The tuple associated with the current cursor position -or-
* null either if there is no visitable tuple
* corresponding to the current cursor position or if the current
* cursor position is undefined.
*/
ITuple tuple();
/**
* Position the cursor on the first visitable tuple ordered greater than the
* current cursor position in the natural key order of the index and return
* that tuple.
*
* @return The tuple -or- null iff there is no such visitable
* tuple.
*/
ITuple nextTuple();
/**
* Position the cursor on the first visitable tuple ordered less than the
* current cursor position in the natural key order of the index and return
* that tuple.
*
* @return The tuple -or- null iff there is no such visitable
* tuple.
*/
ITuple priorTuple();
// /**
// * Change the half-open range for the cursor. This can be useful if you want
// * to perform a series of key-range scans. If the {@link #currentKey()} is
// * no longer within the bounds for the cursor it will not be on a visitable
// * tuple after invoking this method and you must {@link #seek(byte[])} to a
// * key in the new half-open range before you can use the sequential access
// * methods or visit the current tuple.
// *
// * Note: The bounds may be constrained or relaxed, but never relaxed beyond
// * those given when the cursor was provisioned. For example, if you
// * initially specify neither a lower bound nor an upper bound then the
// * bounds may be set to any half-open range. However, if there is a lower
// * bound then you can never shift the lower bound to a lessor value so as to
// * expose additional keys. Likewise, if there is an upper bound then you can
// * never shift the upper bound to a greater value so as to expose additional
// * keys.
// *
// * @param fromKey
// * The optional inclusive lower bound imposed by the
// * {@link ITupleCursor}.
// * @param toKey
// * The optional exclusive upper bound imposed by the
// * {@link ITupleCursor}.
// */
// void bounds(byte[] fromKey, byte[] toKey);
}