org.apache.hadoop.mapreduce.lib.db

クラス TextSplitter

java.lang.Object

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

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

すべての実装されたインタフェース:

DBSplitter

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

Implement DBSplitter over text strings.

コンストラクタのサマリー

コンストラクタ

コンストラクタと説明
TextSplitter()

メソッドのサマリー

修飾子とタイプ	メソッドと説明
List<InputSplit>	split(Configuration conf, ResultSet results, String colName) This method needs to determine the splits between two user-provided strings.

クラスから継承されたメソッド org.apache.hadoop.mapreduce.lib.db.BigDecimalSplitter

tryDivide

クラスから継承されたメソッド java.lang.Object

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

コンストラクタの詳細

TextSplitter

public TextSplitter()

メソッドの詳細

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.

定義:

split インタフェース内 DBSplitter

オーバーライド:

split クラス内 BigDecimalSplitter

例外:

SQLException