com.mapr.db.rowcol

Class IdValueComparator

java.lang.Object

org.apache.hadoop.io.WritableComparator

com.mapr.db.rowcol.IdValueComparator

All Implemented Interfaces:

java.util.Comparator, org.apache.hadoop.conf.Configurable, org.apache.hadoop.io.RawComparator

public class IdValueComparator
extends org.apache.hadoop.io.WritableComparator

This class is used to compare Value objects. This is used M/R framework for sorting rows based on id.

Constructor Summary

Constructors

Constructor and Description
IdValueComparator()

Method Summary

Methods

Modifier and Type	Method and Description
int	compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) Comparator that is used by M/R framework to sort keys between different phases of M/R job.
int	compare(java.lang.Object v1, java.lang.Object v2)
int	compareTo(org.ojai.Value val1, org.ojai.Value val2) Comparator of two value objects.

Methods inherited from class org.apache.hadoop.io.WritableComparator

compare, compareBytes, define, get, get, getConf, getKeyClass, hashBytes, hashBytes, newKey, readDouble, readFloat, readInt, readLong, readUnsignedShort, readVInt, readVLong, setConf

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Comparator

equals

Constructor Detail

IdValueComparator

public IdValueComparator()

Method Detail

compare

public int compare(byte[] b1,
          int s1,
          int l1,
          byte[] b2,
          int s2,
          int l2)

Comparator that is used by M/R framework to sort keys between different phases of M/R job. Input data is serialized with four bytes length (as int) followed by actual key in serialized form. Due to this, we need to skip first four bytes in comparator in order to ensure that the sorting is done in lexicographic order.

Specified by:

compare in interface org.apache.hadoop.io.RawComparator

Overrides:

compare in class org.apache.hadoop.io.WritableComparator

Parameters:

: - b1 : byte array with serialized key1.

: - s1 : offset of key1 in b1.

: - l1 : length of serialized key1.

: - b2 : byte array with serialized key2.

: - s2 : offset of key2 in b2.

: - l2 : length of serialized key2.

Returns:

integer <0, 0, or >0 to indicate if key1 is less than, same or greater than key2.

compareTo

public int compareTo(org.ojai.Value val1,
            org.ojai.Value val2)

Comparator of two value objects.

Parameters:

val1 - : First instance of value.

val2 - : Second instance of value.

Returns:

integer value 0, <0 or >0 to indicate if val1 is same as, less than or greater than val2 respectively.

compare

public int compare(java.lang.Object v1,
          java.lang.Object v2)

Specified by:

compare in interface java.util.Comparator

Overrides:

compare in class org.apache.hadoop.io.WritableComparator