com.bigdata.service.geospatial

Class ZOrderRangeScanUtil

java.lang.Object

com.bigdata.service.geospatial.ZOrderRangeScanUtil

public class ZOrderRangeScanUtil
extends Object

Class providing utility functions for efficient zOrder-based multi-dimensional range scans, such as efficient range checks and functionality for BigMin calculation. The latter follows the logics defined in the BIGMIN decision table as provided in http://www.vision-tools.com/h-tropf/multidimensionalrangequery.pdf, page 76. This class is not thread-safe.

Version:

$Id$

Author:

Michael Schmidt

Constructor Summary

Constructors

Constructor and Description
ZOrderRangeScanUtil(byte[] searchMinZOrder, byte[] searchMaxZOrder, int numDimensions) Constructor for the ZOrderRangeScanUtil.

Method Summary

Methods

Modifier and Type	Method and Description
byte[]	calculateBigMin(byte[] dividingRecord) Returns the BIGMIN, i.e.
boolean	isInSearchRange(byte[] dividingRecord) Checks if the dividing record passed as arguments is in the multi-dimensional search range defined by this class.
static void	load(boolean setFirst, int position, byte[] arr, int numDimensions) Implements the load function from p.75 in http://www.vision-tools.com/h-tropf/multidimensionalrangequery.pdf: If firstBitSet, then load 10000...

Methods inherited from class java.lang.Object

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

Constructor Detail

ZOrderRangeScanUtil

public ZOrderRangeScanUtil(byte[] searchMinZOrder,
                   byte[] searchMaxZOrder,
                   int numDimensions)

Constructor for the ZOrderRangeScanUtil.

Parameters:

searchMinZOrder - the top-left (minimum) value

searchMaxZOrder - the bottom-righ (maximum) value

numDimensions - the number of dimensions

Method Detail

isInSearchRange

public boolean isInSearchRange(byte[] dividingRecord)

Checks if the dividing record passed as arguments is in the multi-dimensional search range defined by this class.

calculateBigMin

public byte[] calculateBigMin(byte[] dividingRecord)

Returns the BIGMIN, i.e. the next relevant value in the search range. The value is returned as unsigned, which needs to be converted into two's complement prior to appending as a key (see GeoSpatialLiteralExtension for details). This method implements the BIGMIN decision table as provided in http://www.vision-tools.com/h-tropf/multidimensionalrangequery.pdf, see page 76.

Parameters:

iv - the IV of the dividing record

Returns:

load

public static void load(boolean setFirst,
        int position,
        byte[] arr,
        int numDimensions)

Implements the load function from p.75 in http://www.vision-tools.com/h-tropf/multidimensionalrangequery.pdf: If firstBitSet, then load 10000... is executed as defined in the paper (setting the bit identified through position to 1 and all following bits in the respective dimension to 0); otherwise load 01111... is executed (which sets the bit identified through position to 0 and all following bits of the dimension to 1). The method has no return value, but instead as a side effect the passed array arr will be modified.