概述
只要是配置了正确的文件类型和压缩类型(比如Textfile+Gzip、SequenceFile+Snappy等),Hive都可以预期读取并解析数据,提供SQL功能。
SequenceFile本身的结构已经设计了内容进行压缩。所以对于SequenceFile文件的压缩,并不是先生成SequenceFile文件,再对文件进行压缩。而是生成SequenceFile文件时,对其中的内容字段进行压缩。最终压缩后,对外仍体现为一个SequenceFile。
RCFile、ORCFile、Parquet、Avro对于压缩的处理方式与SequenceFile相同。
文件格式
Textfile
SequenceFile
RCFile
ORCFile
Parquet
Avro
压缩算法的编解码器
序号 | 压缩格式 | 算法 | 多文件 | 可分割性 | 工具 | 工具压缩后扩展名 |
1 | DEFLATE | DEFLATE | 不 | 不 | 无 | .deflate |
2 | Gzip | DEFLATE | 不 | 不 | gzip | .gz |
3 | bzip2 | bzip2 | 不 | 是 | bzip2 | .bz2 |
4 | LZO | LZO | 不 | 不 | lzop | .lzo |
5 | LZ4 | ?? | ?? | ?? | ?? | ?? |
6 | Snappy | ?? | ?? | ?? | ?? | ?? |
7 | ZLIB | ?? | ?? | ?? | ?? | ?? |
8 | ZIP | DEFLATE | 是 | 是,在文件范围内 | zip | .zip |
一、TEXTFILE
1、文本文件,非压缩
文本文件格式
文件文件(TEXTFILE)格式是Hive中默认的存储格式,在创建Hive 表时如果不指定存储格式即为文本文件。文本文件中每一行数据就是一条记录,可以用任意的分隔符进行分割,也方便和其他的工具进行数据共享、查看和编辑,比如sed,awk等。但相对于二进制文件,文本文件存储的空间较大。
TEXTFILE的数据不做压缩,磁盘开销大,数据解析开销大。可结合Gzip、Bzip2、Snappy等使用(系统自动检查,执行查询时自动解压),但使用这种方式,hive不会对数据进行切分,从而无法对数据进行并行操作。
--创建一个表,格式为文本文件: CREATE EXTERNAL TABLE student_text (id STRING, name STRING) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' LINES TERMINATED BY ' ' STORED AS TEXTFILE; --导入数据到此表中,将启动MR任务 INSERT OVERWRITE TABLE student_text SELECT * FROM student;
可查看到生成的数据文件的格式为非压缩的文本文件:
hdfs dfs -cat /user/hive/warehouse/student_text/000000_0 1001810081,cheyo 1001810082,pku 1001810083,rocky 1001810084,stephen 2002820081,sql 2002820082,hello 2002820083,hijj 3001810081,hhhhhhh 3001810082,abbbbbb
2、文本文件,DEFLATE压缩
--创建一个表,格式为文件文件: CREATE TABLE student_text_def (id STRING, name STRING) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' LINES TERMINATED BY ' ' STORED AS TEXTFILE; --设置压缩类型为DEFLATE压缩 SET hive.exec.compress.output=true; SET mapred.output.compress=true; SET mapred.output.compression.codec=org.apache.hadoop.io.compress.DefaultCodec; --导入数据: INSERT OVERWRITE TABLE student_text_def SELECT * FROM student; --查看数据 SELECT * FROM student_text_def;
查看数据文件,可看到数据文件为多个.deflate文件。
hdfs dfs -ls /user/hive/warehouse/student_text_def/ -rw-r--r-- 2015-09-16 12:48 /user/hive/warehouse/student_text_def/000000_0.deflate -rw-r--r-- 2015-09-16 12:48 /user/hive/warehouse/student_text_def/000001_0.deflate -rw-r--r-- 2015-09-16 12:48 /user/hive/warehouse/student_text_def/000002_0.deflate
3、文本文件,Gzip压缩
--创建一个表,格式为文件文件: CREATE TABLE student_text_gzip (id STRING, name STRING) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' LINES TERMINATED BY ' ' STORED AS TEXTFILE; --设置压缩类型为Gzip压缩 SET hive.exec.compress.output=true; SET mapred.output.compress=true; SET mapred.output.compression.codec=org.apache.hadoop.io.compress.GzipCodec; --导入数据: INSERT OVERWRITE TABLE student_text_gzip SELECT * FROM student; --查看数据 S SELECT * FROM student_text_gzip;
查看数据文件,可看到数据文件为多个.gz文件。解开.gz文件,可以看到明文文本:
hdfs dfs -ls /user/hive/warehouse/student_text_gzip/ -rw-r--r-- 2015-09-15 10:03 /user/hive/warehouse/student_text_gzip/000000_0.gz -rw-r--r-- 2015-09-15 10:03 /user/hive/warehouse/student_text_gzip/000001_0.gz -rw-r--r-- 2015-09-15 10:03 /user/hive/warehouse/student_text_gzip/000002_0.gz
4、文本文件,Bzip2压缩
--创建一个表,格式为文件文件: CREATE TABLE student_text_bzip2 (id STRING, name STRING) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' LINES TERMINATED BY ' ' STORED AS TEXTFILE; - --设置压缩类型为Bzip2压缩: SET hive.exec.compress.output=true; SET mapred.output.compress=true; SET mapred.output.compression.codec=org.apache.hadoop.io.compress.BZip2Codec; --导入数据 INSERT OVERWRITE TABLE student_text_bzip2 SELECT * FROM student; --查看数据: SELECT * FROM student_text_bzip2;
查看数据文件,可看到数据文件为多个.bz2文件。解开.bz2文件,可以看到明文文本:
hdfs dfs -ls /user/hive/warehouse/student_text_bzip2 -rw-r--r-- 2015-09-15 10:09 /user/hive/warehouse/student_text_bzip2/000000_0.bz2 -rw-r--r-- 2015-09-15 10:09 /user/hive/warehouse/student_text_bzip2/000001_0.bz2 -rw-r--r-- 2015-09-15 10:09 /user/hive/warehouse/student_text_bzip2/000002_0.bz2
5、文本文件,lzo压缩
--创建表 C CREATE TABLE student_text_lzo (id STRING, name STRING) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' LINES TERMINATED BY ' ' STORED AS TEXTFILE; --设置为LZO压缩 SET hive.exec.compress.output=true; SET mapred.output.compress=true; SET mapred.output.compression.codec=com.hadoop.compression.lzo.LzopCodec; --导入数据 INSERT OVERWRITE TABLE student_text_lzo SELECT * FROM student; --查询数据 SELECT * FROM student_text_lzo;
create external table `cp_api_log`(`line` string) partitioned by (`date` string) stored as INPUTFORMAT 'com.hadoop.mapred.DeprecatedLzoTextInputFormat' OUTPUTFORMAT 'org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat' location 'hdfs://hdfs://BigdataCluster/user/hive/warehouse/sm_data.db/ods/ods_cp_api'
查看数据文件,可看到数据文件为多个.lzo压缩。解开.lzo文件,可以看到明文文本。
未实测,需要安装lzop库
6、文本文件,lz4压缩
--创建表 C CREATE TABLE student_text_lz4 (id STRING, name STRING) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' LINES TERMINATED BY ' ' STORED AS TEXTFILE; --设置为LZ4压缩 SET hive.exec.compress.output=true; SET mapred.output.compress=true; SET mapred.output.compression.codec=org.apache.hadoop.io.compress.Lz4Codec; --导入数据 INSERT OVERWRITE TABLE student_text_lz4 SELECT * FROM student;
查看数据文件,可看到数据文件为多个.lz4压缩。使用ls查看.lz4文件,可以看到是压缩后的文本。
hdfs dfs -ls /user/hive/warehouse/student_text_lz4 -rw-r--r-- 2015-09-16 12:06 /user/hive/warehouse/student_text_lz4/000000_0.lz4 -rw-r--r-- 2015-09-16 12:06 /user/hive/warehouse/student_text_lz4/000001_0.lz4 -rw-r--r-- 2015-09-16 12:06 /user/hive/warehouse/student_text_lz4/000002_0.lz4
7、文本文件,Snappy压缩
--创建表 C CREATE TABLE student_text_snappy (id STRING, name STRING) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' LINES TERMINATED BY ' ' STORED AS TEXTFILE; --设置压缩 SET hive.exec.compress.output=true; SET mapred.compress.map.output=true; SET mapred.output.compress=true; SET mapred.output.compression=org.apache.hadoop.io.compress.SnappyCodec; SET mapred.output.compression.codec=org.apache.hadoop.io.compress.SnappyCodec; SET io.compression.codecs=org.apache.hadoop.io.compress.SnappyCodec; --导入数据 INSERT OVERWRITE TABLE student_text_snappy SELECT * FROM student; --查询数据 SELECT * FROM student_text_snappy;
查看数据文件,可看到数据文件为多个.snappy压缩文件。使用ls查看.snappy文件,可以看到是压缩后的文本:
hdfs dfs -ls /user/hive/warehouse/student_text_snappy Found 3 items -rw-r--r-- 2015-09-15 16:42 /user/hive/warehouse/student_text_snappy/000000_0.snappy -rw-r--r-- 2015-09-15 16:42 /user/hive/warehouse/student_text_snappy/000001_0.snappy -rw-r--r-- 2015-09-15 16:42 /user/hive/warehouse/student_text_snappy/000002_0.snappy
二、SEQUENCEFILE
1、Sequence文件,DEFLATE压缩
--创建一个表,格式为文件文件: CREATE TABLE student_seq_def (id STRING, name STRING) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' LINES TERMINATED BY ' ' STORED AS SEQUENCEFILE; --设置压缩类型为Gzip压缩 SET hive.exec.compress.output=true; SET mapred.output.compress=true; SET mapred.output.compression.codec=org.apache.hadoop.io.compress.DefaultCodec; --导入数据: INSERT OVERWRITE TABLE student_seq_def SELECT * FROM student; --查看数据 SELECT * FROM student_seq_def;
查看数据文件,是一个密文的文件.
hdfs dfs -ls /user/hive/warehouse/student_seq_def/ -rw-r--r-- /user/hive/warehouse/student_seq_def/000000_0
2、Sequence文件,Gzip压缩
--创建一个表,格式为文件文件: CREATE TABLE student_seq_gzip (id STRING, name STRING) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' LINES TERMINATED BY ' ' STORED AS SEQUENCEFILE; - --设置压缩类型为Gzip压缩 SET hive.exec.compress.output=true; SET mapred.output.compress=true; SET mapred.output.compression.codec=org.apache.hadoop.io.compress.GzipCodec; --导入数据: INSERT OVERWRITE TABLE student_seq_gzip SELECT * FROM student; --查看数据 SELECT * FROM student_seq_gzip;
查看数据文件,是一个密文的文件,无法通过gzip解压:
hdfs dfs -ls /user/hive/warehouse/student_seq_gzip/ -rw-r--r-- /user/hive/warehouse/student_seq_gzip/000000_0
三、RCFILE
1、RCFILE,Gzip压缩
CREATE TABLE student_rcfile_gzip (id STRING, name STRING) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' LINES TERMINATED BY ' ' STORED AS RCFILE; - --设置压缩类型为Gzip压缩 SET hive.exec.compress.output=true; SET mapred.output.compress=true; SET mapred.output.compression.codec=org.apache.hadoop.io.compress.GzipCodec; --导入数据: INSERT OVERWRITE TABLE student_rcfile_gzip SELECT id,name FROM student; --查看数据 SELECT * FROM student_rcfile_gzip;
四、ORCFile
ORCFile有自己的参数设置压缩格式,一般不使用上述Hive参数设置压缩参数。
参考文档:LanguageManual ORC(https://cwiki.apache.org/confluence/display/Hive/LanguageManual+ORC)
1、ORCFile,ZLIB压缩
--创建表 CREATE TABLE student_orcfile_zlib (id STRING, name STRING) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' LINES TERMINATED BY ' ' STORED AS ORCFILE TBLPROPERTIES ("orc.compress"="ZLIB"); - --导入数据 INSERT OVERWRITE TABLE student_orcfile_zlib SELECT id,name FROM student; --查询数据 SELECT * FROM student_orcfile_zlib;
2、ORCFILE,Snappy压缩
--创建表 C CREATE TABLE student_orcfile_snappy2 (id STRING, name STRING) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' LINES TERMINATED BY ' ' STORED AS ORCFILE TBLPROPERTIES ("orc.compress"="SNAPPY"); - --导入数据 I INSERT OVERWRITE TABLE student_orcfile_snappy2 SELECT id,name FROM student; --查询数据 SELECT * FROM student_orcfile_snappy2;
create external table `cp_api_log`(`line` string) partitioned by (`date` string) row format serde 'com.cloudera.hive.serde.JSONSerDe' stored as orc tblproperties ("orc.compress"="SNAPPY") location 'hdfs://hdfs://BigdataCluster/user/hive/warehouse/sm_data.db/ods/ods_cp_api'
一般不使用下述方式。下述方式压缩后,结果与上述同类型压缩(SNAPPY)不同。具体原因待进一步研究。
--创建表 CREATE TABLE student_orcfile_snappy (id STRING, name STRING) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' LINES TERMINATED BY ' ' STORED AS ORCFILE; --设置压缩 SET hive.exec.compress.output=true; SET mapred.compress.map.output=true; SET mapred.output.compress=true; SET mapred.output.compression=org.apache.hadoop.io.compress.SnappyCodec; SET mapred.output.compression.codec=org.apache.hadoop.io.compress.SnappyCodec; SET io.compression.codecs=org.apache.hadoop.io.compress.SnappyCodec; --导入数据 INSERT OVERWRITE TABLE student_orcfile_snappy SELECT id,name FROM student; --查询数据 SELECT * FROM student_orcfile_snappy;
五、Parquet
1、Parquet,Snappy压缩
--创建表 CREATE TABLE student_parquet_snappy (id STRING, name STRING) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' LINES TERMINATED BY ' ' STORED AS PARQUET; --设置压缩 SET hive.exec.compress.output=true; SET mapred.compress.map.output=true; SET mapred.output.compress=true; SET mapred.output.compression=org.apache.hadoop.io.compress.SnappyCodec; SET mapred.output.compression.codec=org.apache.hadoop.io.compress.SnappyCodec; SET io.compression.codecs=org.apache.hadoop.io.compress.SnappyCodec; --导入数据 INSERT OVERWRITE TABLE student_parquet_snappy SELECT id,name FROM student; --查询数据 SELECT * FROM student_parquet_snappy;
六、Avro
1、Avro,Snappy压缩
--创建表 CREATE TABLE student_avro_snappy (id STRING, name STRING) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' LINES TERMINATED BY ' ' STORED AS AVRO; --设置压缩 SET hive.exec.compress.output=true; SET mapred.compress.map.output=true; SET mapred.output.compress=true; SET mapred.output.compression=org.apache.hadoop.io.compress.SnappyCodec; SET mapred.output.compression.codec=org.apache.hadoop.io.compress.SnappyCodec; SET io.compression.codecs=org.apache.hadoop.io.compress.SnappyCodec; --导入数据 INSERT OVERWRITE TABLE student_avro_snappy SELECT id,name FROM student; --查询数据 SELECT * FROM student_avro_snappy;