org.apache.hadoop.mapreduce.lib.db

类 TextSplitter

java.lang.Object

org.apache.hadoop.mapreduce.lib.db.BigDecimalSplitter

org.apache.hadoop.mapreduce.lib.db.TextSplitter

所有已实现的接口:

DBSplitter

@InterfaceAudience.Public
@InterfaceStability.Evolving
public class TextSplitter
extends BigDecimalSplitter

Implement DBSplitter over text strings.

构造器概要

构造器

构造器和说明
TextSplitter()

方法概要

方法

限定符和类型	方法和说明
List<InputSplit>	split(Configuration conf, ResultSet results, String colName) This method needs to determine the splits between two user-provided strings.

从类继承的方法 org.apache.hadoop.mapreduce.lib.db.BigDecimalSplitter

tryDivide

从类继承的方法 java.lang.Object

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

构造器详细资料

TextSplitter

public TextSplitter()

方法详细资料

split

public List<InputSplit> split(Configuration conf,
                     ResultSet results,
                     String colName)
                       throws SQLException

This method needs to determine the splits between two user-provided strings. In the case where the user's strings are 'A' and 'Z', this is not hard; we could create two splits from ['A', 'M') and ['M', 'Z'], 26 splits for strings beginning with each letter, etc. If a user has provided us with the strings "Ham" and "Haze", however, we need to create splits that differ in the third letter. The algorithm used is as follows: Since there are 2**16 unicode characters, we interpret characters as digits in base 65536. Given a string 's' containing characters s_0, s_1 .. s_n, we interpret the string as the number: 0.s_0 s_1 s_2.. s_n in base 65536. Having mapped the low and high strings into floating-point values, we then use the BigDecimalSplitter to establish the even split points, then map the resulting floating point values back into strings.

指定者:

split 在接口中 DBSplitter

覆盖:

split 在类中 BigDecimalSplitter

抛出:

SQLException