Hive之配置和使用LZO压缩

前言

• OS：CentOS 7

• Hive：2.3.0

• Hadoop：2.7.7

• MySQL Server：5.7.10

• Hive官方手册：LanguageManual LZO

• 在配置Hive使用lzo压缩功能之前，需要保证Hadoop集群中lzo依赖库的正确安装，以及hadoop-lzo依赖的正确配置，可以参考：Hadoop配置lzo压缩

• 温馨提示：Hive自定义组件打包时，不要同时打包依赖，避免各种版本冲突，只将额外的依赖添加到classpath中即可

---

配置过程

一、配置Hadoop集群

• 在core-site.xml文件的io.compression.codecs参数中添加lzo、lzop压缩对应的编解码器类，并配置io.compression.codec.lzo.class参数，具体如下所示：

    
    <property>
        <name>io.compression.codecsname>
        <value>
            org.apache.hadoop.io.compress.GzipCodec,
            org.apache.hadoop.io.compress.DefaultCodec,
            org.apache.hadoop.io.compress.DeflateCodec,
            org.apache.hadoop.io.compress.BZip2Codec,
            org.apache.hadoop.io.compress.SnappyCodec,
            org.apache.hadoop.io.compress.Lz4Codec,
            com.hadoop.compression.lzo.LzoCodec,
            com.hadoop.compression.lzo.LzopCodec
        value>
        <description>
            A comma-separated list of the compression codec classes that can
            be used for compression/decompression. In addition to any classes specified
            with this property (which take precedence), codec classes on the classpath
            are discovered using a Java ServiceLoader.
        description>
    property>

    
    <property>
        <name>io.compression.codec.lzo.classname>
        <value>com.hadoop.compression.lzo.LzoCodecvalue>
    property>

• 在mapred-site.xml文件中配置如下参数，设置MR Job执行时使用的压缩方式：

    
    
    <property>
        <name>mapreduce.map.output.compressname>
        <value>truevalue>
        <description>
            Should the outputs of the maps be compressed before being
            sent across the network. Uses SequenceFile compression.
        description>
    property>
    
    
    <property>
        <name>mapreduce.map.output.compress.codecname>
        <value>com.hadoop.compression.lzo.LzoCodecvalue>
        <description>
            If the map outputs are compressed, how should they be compressed?
        description>
    property>
    
    
    <property>
        <name>mapreduce.output.fileoutputformat.compressname>
        <value>truevalue>
        <description>Should the job outputs be compressed?
        description>
    property>
    
    
    <property>
        <name>mapreduce.output.fileoutputformat.compress.codecname>
        <value>com.hadoop.compression.lzo.LzoCodecvalue>
        <description>If the job outputs are compressed, how should they be compressed?
        description>
    property>
    
    
    <property>
        <name>mapreduce.output.fileoutputformat.compress.typename>
        <value>BLOCKvalue>
        <description>If the job outputs are to compressed as SequenceFiles, how should
               they be compressed? Should be one of NONE, RECORD or BLOCK.
        description>
    property>

---

二、配置Hive

在$HIVE_HOME/conf/hive-site.xml文件中设置如下参数，使得Hive进行查询时使用压缩功能，具体使用的压缩算法默认与Hadoop中的配置相同，当然也有相应的参数可以进行覆盖：

    
    
    <property>
        <name>hive.exec.compress.outputname>
        <value>truevalue>
        <description>
            This controls whether the final outputs of a query (to a local/HDFS file or a Hive table) 
            is compressed. 
            The compression codec and other options are determined from Hadoop config variables 
            mapred.output.compress*
        description>
    property>
    
    
    <property>
        <name>hive.exec.compress.intermediatename>
        <value>truevalue>
        <description>
            This controls whether intermediate files produced by Hive between multiple map-reduce jobs are compressed. 
            The compression codec and other options are determined from Hadoop config variables mapred.output.compress*
        description>
    property>

---

三、建立支持lzo压缩数据读取和写入的Hive表

• 示例：

CREATE TABLE tmp like emp
STORED AS
INPUTFORMAT "com.hadoop.mapred.DeprecatedLzoTextInputFormat"
OUTPUTFORMAT "org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat";

• 注意1：当前版本（2.3.0）的Hive只支持使用旧版本MR框架（com.hadoop.mapred）的API，使用的InputFormat必须实现org.apache.hadoop.mapred.InputFormat接口
• 注意2：当前版本（2.3.0）的Hive中要想使用lzo压缩，需要将表数据读取时使用的InputFormat设置为com.hadoop.mapred.DeprecatedLzoTextInputFormat，此工具类在hadoop-lzo的jar包中（如：hadoop-lzo-0.4.20.jar）。只有使用LzoTextInputFormat才能避免将lzo索引文件识别成数据文件，又因为Hive支持支旧版本API，因此必须使用示例中的DeprecatedLzoTextInputFormat才能使用lzo的分片功能。
• 注意3：使用DeprecatedLzoTextInputFormat只能识别后缀为.lzo的lzo压缩文件，无法识别后缀为.lzo_deflate的lzo压缩文件。前者是使用编解码器LzopCodec生成的，后者是使用LzoCodec生成的，.lzo压缩文件能够创建索引，而.lzo_deflate压缩文件无法创建索引，只有建立了lzo索引才能使用lzo分片功能。

PS：可以通过以下命令，来修改表的InputFormat/Outputformat/SerDe

-- 可以通过以下命令,修改表数据的读取/写入/序列化和反序列化方式
ALTER TABLE tmp
SET FILEFORMAT
INPUTFORMAT "com.hadoop.mapred.DeprecatedLzoTextInputFormat"
OUTPUTFORMAT "org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat" -- Hive默认Outputformat
SERDE 'org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe'; -- Hive默认SERDE

---

四、导入lzo压缩文件，并对.lzo压缩文件建立lzo索引

• 导入表数据文件（.lzo压缩文件）

LOAD DATA INPATH '/tmp/data/output/emp/000000_0.lzo' OVERWRITE INTO TABLE tmp;

• 为.lzo压缩文件建立lzo索引，便于读取时能够进行切割分片，否则只能将整个文件作为单个分片。示例命令如下，使用的是hadoop-lzo依赖中的工具类来为lzo压缩文件创建索引，索引文件与压缩文件在同一路径下，后缀名为.lzo.index

hadoop jar \
/opt/module/hadoop-2.7.7/share/hadoop/common/hadoop-lzo-0.4.21-SNAPSHOT.jar \
com.hadoop.compression.lzo.DistributedLzoIndexer \
/user/hive/warehouse/test.db/tmp/000000_0.lzo

• 查看索引是否建立成功

[tomandersen@hadoop101 libs]$ hadoop fs -ls /user/hive/warehouse/test.db/tmp/;
Found 2 items
-rwxr-xr-x   1 tomandersen supergroup        515 2020-06-19 17:43 /user/hive/warehouse/test.db/tmp/000000_0.lzo
-rw-r--r--   1 tomandersen supergroup          8 2020-06-21 21:53 /user/hive/warehouse/test.db/tmp/000000_0.lzo.index

---

五、查询表数据，验证能够正常读取

• 设置InputFormat为DeprecatedLzoTextInputFormat，不再将lzo索引文件视为数据文件，读取结果正常

0: jdbc:hive2://hadoop101:10000/default (test)> select * from test.tmp;
+------------+------------+----------+------------+----------+---------------+----------+-----------+-------------+
| tmp.empno  | tmp.ename  | tmp.sex  |  tmp.job   | tmp.mgr  | tmp.hiredate  | tmp.sal  | tmp.comm  | tmp.deptno  |
+------------+------------+----------+------------+----------+---------------+----------+-----------+-------------+
| 7369       | SMITH      | male     | CLERK      | 7902     | 1980-12-17    | 800.0    | NULL      | 20          |
| 7499       | ALLEN      | male     | SALESMAN   | 7698     | 1981-2-20     | 1600.0   | 300.0     | 30          |
| 7521       | WARD       | female   | SALESMAN   | 7698     | 1981-2-22     | 1250.0   | 500.0     | 30          |
| 7566       | JONES      | male     | MANAGER    | 7839     | 1981-4-2      | 2975.0   | NULL      | 20          |
| 7654       | MARTIN     | female   | SALESMAN   | 7698     | 1981-9-28     | 1250.0   | 1400.0    | 30          |
| 7698       | BLAKE      | male     | MANAGER    | 7839     | 1981-5-1      | 2850.0   | NULL      | 30          |
| 7782       | CLARK      | male     | MANAGER    | 7839     | 1981-6-9      | 2450.0   | NULL      | 10          |
| 7788       | SCOTT      | male     | ANALYST    | 7566     | 1987-4-19     | 3000.0   | NULL      | 20          |
| 7839       | KING       | female   | PRESIDENT  | NULL     | 1981-11-17    | 5000.0   | NULL      | 10          |
| 7844       | TURNER     | female   | SALESMAN   | 7698     | 1981-9-8      | 1500.0   | 0.0       | 30          |
| 7876       | ADAMS      | male     | CLERK      | 7788     | 1987-5-23     | 1100.0   | NULL      | 20          |
| 7900       | JAMES      | male     | CLERK      | 7698     | 1981-12-3     | 950.0    | NULL      | 30          |
| 7902       | FORD       | male     | ANALYST    | 7566     | 1981-12-3     | 3000.0   | NULL      | 20          |
| 7934       | MILLER     | female   | CLERK      | 7782     | 1982-1-23     | 1300.0   | NULL      | 10          |
+------------+------------+----------+------------+----------+---------------+----------+-----------+-------------+
14 rows selected (0.244 seconds)

• 未设置InputFormat为DeprecatedLzoTextInputFormat，会将lzo索引文件视为数据文件进行读取，查询结果会多出一行NULL值

0: jdbc:hive2://hadoop101:10000/default (test)> select * from test.tmp;
+------------+------------+----------+------------+----------+---------------+----------+-----------+-------------+
| tmp.empno  | tmp.ename  | tmp.sex  |  tmp.job   | tmp.mgr  | tmp.hiredate  | tmp.sal  | tmp.comm  | tmp.deptno  |
+------------+------------+----------+------------+----------+---------------+----------+-----------+-------------+
| 7369       | SMITH      | male     | CLERK      | 7902     | 1980-12-17    | 800.0    | NULL      | 20          |
| 7499       | ALLEN      | male     | SALESMAN   | 7698     | 1981-2-20     | 1600.0   | 300.0     | 30          |
| 7521       | WARD       | female   | SALESMAN   | 7698     | 1981-2-22     | 1250.0   | 500.0     | 30          |
| 7566       | JONES      | male     | MANAGER    | 7839     | 1981-4-2      | 2975.0   | NULL      | 20          |
| 7654       | MARTIN     | female   | SALESMAN   | 7698     | 1981-9-28     | 1250.0   | 1400.0    | 30          |
| 7698       | BLAKE      | male     | MANAGER    | 7839     | 1981-5-1      | 2850.0   | NULL      | 30          |
| 7782       | CLARK      | male     | MANAGER    | 7839     | 1981-6-9      | 2450.0   | NULL      | 10          |
| 7788       | SCOTT      | male     | ANALYST    | 7566     | 1987-4-19     | 3000.0   | NULL      | 20          |
| 7839       | KING       | female   | PRESIDENT  | NULL     | 1981-11-17    | 5000.0   | NULL      | 10          |
| 7844       | TURNER     | female   | SALESMAN   | 7698     | 1981-9-8      | 1500.0   | 0.0       | 30          |
| 7876       | ADAMS      | male     | CLERK      | 7788     | 1987-5-23     | 1100.0   | NULL      | 20          |
| 7900       | JAMES      | male     | CLERK      | 7698     | 1981-12-3     | 950.0    | NULL      | 30          |
| 7902       | FORD       | male     | ANALYST    | 7566     | 1981-12-3     | 3000.0   | NULL      | 20          |
| 7934       | MILLER     | female   | CLERK      | 7782     | 1982-1-23     | 1300.0   | NULL      | 10          |
| NULL       | NULL       | NULL     | NULL       | NULL     | NULL          | NULL     | NULL      | NULL        |
+------------+------------+----------+------------+----------+---------------+----------+-----------+-------------+
15 rows selected (0.229 seconds)

---

报错及解决方案

• 报错一：Compression codec com.hadoop.compression.lzo.LzoCodec not found

解析：很显然这是一个差找不到指定类的Bug，而LzoCodec是hadoop-lzo依赖中的工具类，因此将对应的jar包添加到classpath中即可，解决方案多种多样

解决方案示例：在hive-env.sh配置文件中设置HIVE_AUX_JARS_PATH环境变量，将hadoop-lzo依赖jar包放入此变量所指路径（或者将此变量设置成hadoop-lzo.jar所在路径）。

• 报错二：Error: java.io.IOException: java.io.EOFException: Premature EOF from inputStream

解析：通过查找网上的资料发现，导致这样的报错可能有多种原因，最常见的就是由于在hadoop中lzo的相关配置，与Hive中的表相关设置相冲突（具体原因未知）

解决方案示例：将mapred-site.xml文件中的mapreduce.output.fileoutputformat.compress.codec参数设置成除了com.hadoop.compression.lzo.LzopCodec意以外的其他值，如com.hadoop.compression.lzo.LzoCodec，即更换最终MR输出文件所使用的压缩算法编解码器为非LzopCodec的其他值

---

End~