[Hadoop]Sqoop 1.4.2中文文档（一）之数据导入

一、Sqoop Help

$ sqoop help
usage: sqoop COMMAND [ARGS]

Available commands:
  codegen            Generate code to interact with database records
  create-hive-table  Import a table definition into Hive
  eval               Evaluate a SQL statement and display the results
  export             Export an HDFS directory to a database table
  help               List available commands
  import             Import a table from a database to HDFS
  import-all-tables  Import tables from a database to HDFS
  list-databases     List available databases on a server
  list-tables        List available tables in a database
  version            Display version information

See 'sqoop help COMMAND' for information on a specific command.

你可以使用sqoop help （tool-name）也可以使用sqoop （tool-name）--help来使用帮助。
例如： sqoop help import. sqoop import --help.

二、Sqoop的别名
例如：sqoop import --help 等同于 sqoop-import --help，即sqoop-import是sqoop import的别名。

三、sqoop-import
$ sqoop help import

usage: sqoop import [GENERIC-ARGS] [TOOL-ARGS]

Common arguments:
   --connect <jdbc-uri>     Specify JDBC connect string
   --connect-manager <jdbc-uri>     Specify connection manager class to use
   --driver <class-name>    Manually specify JDBC driver class to use
   --hadoop-home <dir>      Override $HADOOP_HOME
   --help                   Print usage instructions
-P                          Read password from console
   --password <password>    Set authentication password
   --username <username>    Set authentication username
   --verbose                Print more information while working

[...]

Generic Hadoop command-line arguments:
(must preceed any tool-specific arguments)
Generic options supported are
-conf <configuration file>     specify an application configuration file
-D <property=value>            use value for given property
-fs <local|namenode:port>      specify a namenode
-jt <local|jobtracker:port>    specify a job tracker
-files <comma separated list of files>    specify comma separated files to be copied to the map reduce cluster
-libjars <comma separated list of jars>    specify comma separated jar files to include in the classpath.
-archives <comma separated list of archives>    specify comma separated archives to be unarchived on the compute machines.

The general command line syntax is
bin/hadoop command [genericOptions] [commandOptions]

其中Generic option的设置要在Common arguments之前，-conf，-fs，-jt-，-D都是对hadoop服务进行设置的，例如 -D mapred.job.name=<job_name>能够制定job的名字，如果不指定的话Job的名字将以用到的Jar包作为Job的名字。
例如：

User: hdfs
Job Name: cn_opda_a_phonoalbumshoushou_json_120901.jar
Job File: hdfs://vm-nba01.in.dx:9000/home/hdfs/tmp/mapred/staging/hdfs/.staging/job_201210171559_0391/job.xml
Submit Host: vm-nba01.in.dx
Submit Host Address: 10.18.102.101
Job-ACLs: All users are allowed
Job Setup: Successful
Status: Succeeded
Started at: Tue Oct 23 15:18:41 CST 2012
Finished at: Tue Oct 23 15:23:20 CST 2012
Finished in: 4mins, 39sec
Job Cleanup: Successful

而files、libjars 、archives 选项则不具有代表性质，因为这些选项在Hadoop内部命令中已经被支持了，可以查看hadoop job的帮助。

[work@vm-nba01 ~]$ hadoop job
Usage: JobClient <command> <args>
	[-submit <job-file>]
	[-status <job-id>]
	[-counter <job-id> <group-name> <counter-name>]
	[-kill <job-id>]
	[-set-priority <job-id> <priority>]. Valid values for priorities are: VERY_HIGH HIGH NORMAL LOW VERY_LOW
	[-events <job-id> <from-event-#> <#-of-events>]
	[-history <jobOutputDir>]
	[-list [all]]
	[-list-active-trackers]
	[-list-blacklisted-trackers]
	[-list-attempt-ids <job-id> <task-type> <task-state>]

	[-kill-task <task-id>]
	[-fail-task <task-id>]

Generic options supported are
-conf <configuration file>     specify an application configuration file
-D <property=value>            use value for given property
-fs <local|namenode:port>      specify a namenode
-jt <local|jobtracker:port>    specify a job tracker
-files <comma separated list of files>    specify comma separated files to be copied to the map reduce cluster
-libjars <comma separated list of jars>    specify comma separated jar files to include in the classpath.
-archives <comma separated list of archives>    specify comma separated archives to be unarchived on the compute machines.

四、sqoop脚本
举例：

$ sqoop import --connect jdbc:mysql://localhost/db --username foo --table TEST

下面把这些选项参数做成脚本进行传递：（import.txt）

$ sqoop --options-file /users/homer/work/import.txt --table TEST

那么import.txt中的参数要按照行来进行分隔，内容如下：

#
# Options file for Sqoop import
#

# Specifies the tool being invoked
import

# Connect parameter and value
--connect
jdbc:mysql://localhost/db

# Username parameter and value
--username
foo

#
# Remaining options should be specified in the command line.
#

举个sqoop连接数据库，将数据库内的数据导入到HDFS中的例子：

sqoop import --connect jdbc:mysql://database.example.com/employees \
    --username aaron --password 12345

这样连接例子需要把mysql driver的jar包放到你的环境Path中，否则请这样使用：

$ sqoop import --driver com.microsoft.jdbc.sqlserver.SQLServerDriver \
    --connect <connect-string> ...

sqoop-import控制参数：

usage: sqoop import [GENERIC-ARGS] [TOOL-ARGS]

Common arguments:
   --connect <jdbc-uri>                         Specify JDBC connect
                                                string
   --connection-manager <class-name>            Specify connection manager
                                                class name
   --connection-param-file <properties-file>    Specify connection
                                                parameters file
   --driver <class-name>                        Manually specify JDBC
                                                driver class to use
   --hadoop-home <dir>                          Override $HADOOP_HOME
   --help                                       Print usage instructions
-P                                              Read password from console
   --password <password>                        Set authentication
                                                password
   --username <username>                        Set authentication
                                                username
   --verbose                                    Print more information
                                                while working

Import control arguments:
   --append                        Imports data in append mode
   --as-avrodatafile               Imports data to Avro data files
   --as-sequencefile               Imports data to SequenceFiles
   --as-textfile                   Imports data as plain text (default)
   --boundary-query <statement>    Set boundary query for retrieving max
                                   and min value of the primary key
   --columns <col,col,col...>      Columns to import from table
   --compression-codec <codec>     Compression codec to use for import
   --direct                        Use direct import fast path
   --direct-split-size <n>         Split the input stream every 'n' bytes
                                   when importing in direct mode
-e,--query <statement>             Import results of SQL 'statement'
   --fetch-size <n>                Set number 'n' of rows to fetch from
                                   the database when more rows are needed
   --inline-lob-limit <n>          Set the maximum size for an inline LOB
-m,--num-mappers <n>               Use 'n' map tasks to import in parallel
   --split-by <column-name>        Column of the table used to split work
                                   units
   --table <table-name>            Table to read
   --target-dir <dir>              HDFS plain table destination
   --warehouse-dir <dir>           HDFS parent for table destination
   --where <where clause>          WHERE clause to use during import
-z,--compress                      Enable compression

Incremental import arguments:
   --check-column <column>        Source column to check for incremental
                                  change
   --incremental <import-type>    Define an incremental import of type
                                  'append' or 'lastmodified'
   --last-value <value>           Last imported value in the incremental
                                  check column

Output line formatting arguments:
   --enclosed-by <char>               Sets a required field enclosing
                                      character
   --escaped-by <char>                Sets the escape character
   --fields-terminated-by <char>      Sets the field separator character
   --lines-terminated-by <char>       Sets the end-of-line character
   --mysql-delimiters                 Uses MySQL's default delimiter set:
                                      fields: ,  lines: \n  escaped-by: \
                                      optionally-enclosed-by: '
   --optionally-enclosed-by <char>    Sets a field enclosing character

Input parsing arguments:
   --input-enclosed-by <char>               Sets a required field encloser
   --input-escaped-by <char>                Sets the input escape
                                            character
   --input-fields-terminated-by <char>      Sets the input field separator
   --input-lines-terminated-by <char>       Sets the input end-of-line
                                            char
   --input-optionally-enclosed-by <char>    Sets a field enclosing
                                            character

Hive arguments:
   --create-hive-table                         Fail if the target hive
                                               table exists
   --hive-delims-replacement <arg>             Replace Hive record \0x01
                                               and row delimiters (\n\r)
                                               from imported string fields
                                               with user-defined string
   --hive-drop-import-delims                   Drop Hive record \0x01 and
                                               row delimiters (\n\r) from
                                               imported string fields
   --hive-home <dir>                           Override $HIVE_HOME
   --hive-import                               Import tables into Hive
                                               (Uses Hive's default
                                               delimiters if none are
                                               set.)
   --hive-overwrite                            Overwrite existing data in
                                               the Hive table
   --hive-partition-key <partition-key>        Sets the partition key to
                                               use when importing to hive
   --hive-partition-value <partition-value>    Sets the partition value to
                                               use when importing to hive
   --hive-table <table-name>                   Sets the table name to use
                                               when importing to hive
   --map-column-hive <arg>                     Override mapping for
                                               specific column to hive
                                               types.

HBase arguments:
   --column-family <family>    Sets the target column family for the
                               import
   --hbase-create-table        If specified, create missing HBase tables
   --hbase-row-key <col>       Specifies which input column to use as the
                               row key
   --hbase-table <table>       Import to <table> in HBase

Code generation arguments:
   --bindir <dir>                        Output directory for compiled
                                         objects
   --class-name <name>                   Sets the generated class name.
                                         This overrides --package-name.
                                         When combined with --jar-file,
                                         sets the input class.
   --input-null-non-string <null-str>    Input null non-string
                                         representation
   --input-null-string <null-str>        Input null string representation
   --jar-file <file>                     Disable code generation; use
                                         specified jar
   --map-column-java <arg>               Override mapping for specific
                                         columns to java types
   --null-non-string <null-str>          Null non-string representation
   --null-string <null-str>              Null string representation
   --outdir <dir>                        Output directory for generated
                                         code
   --package-name <name>                 Put auto-generated classes in
                                         this package

Generic Hadoop command-line arguments:
(must preceed any tool-specific arguments)
Generic options supported are
-conf <configuration file>     specify an application configuration file
-D <property=value>            use value for given property
-fs <local|namenode:port>      specify a namenode
-jt <local|jobtracker:port>    specify a job tracker
-files <comma separated list of files>    specify comma separated files to be copied to the map reduce cluster
-libjars <comma separated list of jars>    specify comma separated jar files to include in the classpath.
-archives <comma separated list of archives>    specify comma separated archives to be unarchived on the compute machines.

The general command line syntax is
bin/hadoop command [genericOptions] [commandOptions]

五、利用查询结果作为sqoop的导入内容

举例：其中split-by是导入后的数据按照a.id进行分割，--target-dir目标地址，查询后的结果将放入这个文件

$ sqoop import \
  --query 'SELECT a.*, b.* FROM a JOIN b on (a.id == b.id) WHERE $CONDITIONS' \
  --split-by a.id --target-dir /user/foo/joinresults

举例：m代表只查询一次并且边查询边导入

$ sqoop import \
  --query 'SELECT a.*, b.* FROM a JOIN b on (a.id == b.id) WHERE $CONDITIONS' \
  -m 1 --target-dir /user/foo/joinresults

导入时候可以控制分割文件大小，或者字符串转义例如：--direct-split-size 以及--warehouse-dir ，--default-character-set

例如：

$ sqoop import --connect jdbc:mysql://server.foo.com/db --table bar \
    --direct -- --default-character-set=latin1
$ sqoop import --connnect <connect-str> --table foo --warehouse-dir /shared \
    ...

sqoop对java以及hive提供支持，所以你可以导入key/value这样的map数据，例如：

Argument	 Description
--map-column-java <mapping>	 Override mapping from SQL to Java type for configured columns.
--map-column-hive <mapping>	 Override mapping from SQL to Hive type for configured columns.
$ sqoop import ... --map-column-java id=String,value=Integer

六、sqoop的增量导入

Argument	 Description
--check-column (col)	 Specifies the column to be examined when determining which rows to import.
--incremental (mode)	 Specifies how Sqoop determines which rows are new. Legal values for mode include append and lastmodified.
--last-value (value)	 Specifies the maximum value of the check column from the previous import.

通过增量导入你可以只导入一个已经存在表的增列值，或者表后面的值。
增量导入需要给定必要的参数，详情一个增量导入的例子。

当然你也可以指定导入到Hive后的文件格式：有2种
1.--as-textfile
这个参数你可以查看到hive内的原数据就是文本文件模式没有压缩
2.-z or --compress or --compression-codec
这个参数有3种写法不过导入到hive内的数据就是压缩过的了

七、sqoop的Hive与Hbase的数据导入
前六点都能看完后，Hive与Hbase的导入也就很简单了，其实就是多了一步导入的数据放在哪里而已。

Hive举例：

sqoop import --verbose --connect jdbc:mysql://10.18.102.133/tjss_opda --username tongji --password dx_tj --table opda_start_120604 --hive-import --hive-table opda_start_120604_incr  --hive-overwrite --direct

sqoop job --create opda_start_120604 -- import --connect jdbc:mysql://10.18.102.133/tjss_opda --username tongji --password dx_tj --table opda_start_120604 --hive-import --hive-table opda_start_120604_incr --check-column id --incremental append --last-value 0 -m 8 --hive-overwrite --hive-delims-replacement="\t"

注意事项：

1.注意Sqoop是在Hadoop上跑的，所以jdbc url不要写localhost，--direct的要求同理。
2.Sqoop也有metastore，目前看来，没有启动metastore service时其不是线程安全的。另外就是它只能使用hsqldb，暂不支持其他数据库，对hsqldb可靠性没有太高信心。
3.Metastore里password是明文存储的，所以它不建议存储password。
4.Sqoop有bug，目前数据库里有特殊表名时有问题。
5.Sqoop导入到hive里的表只能是TEXTFILE，不过可以选择压缩格式
6.Sqoop可以导入到一个已经存在的空hive表，但是是使用Load data导入数据，所以目标表的schema实际上是被无视了。
7.Sqoop导入hive若不加hive-overwirte，会留下hadoop目录，对下次若执行相同任务有影响。
8.注意加入delims-replace，否则很容易因为分隔符问题出现错误行。
9.Hive进行dynamic partition时，一次partition数量过多有Bug，必须加distribute by
10.Hive对大小写不区分，尽量全小写，否则有潜在bug
11.Sqoop要求运行时当前目录可写（code-gen）。
12.只要有jdbc驱动，所有jdbc兼容的数据库均可导入

导入时除了用到sqoop相关的hive与Hbase的参数外，还会用到导入时候专用的参数：

Input parsing arguments:
   --input-enclosed-by <char>               Sets a required field encloser
   --input-escaped-by <char>                Sets the input escape
                                            character
   --input-fields-terminated-by <char>      Sets the input field separator
   --input-lines-terminated-by <char>       Sets the input end-of-line
                                            char
   --input-optionally-enclosed-by <char>    Sets a field enclosing
                                            character

这个部分的参数有可能你会用到的。另外如果导入语句没有添加目的表或者地址则导入的内容会写在HDFS当前的操作目录下。


八、sqoop导入全部表和数据

举个例子，其他参数均与sqoop help参数相同：

$ sqoop import-all-tables --connect jdbc:mysql://db.foo.com/corp

验证结果：

$ hadoop fs -ls
Found 4 items
drwxr-xr-x   - someuser somegrp       0 2010-04-27 17:15 /user/someuser/EMPLOYEES
drwxr-xr-x   - someuser somegrp       0 2010-04-27 17:15 /user/someuser/PAYCHECKS
drwxr-xr-x   - someuser somegrp       0 2010-04-27 17:15 /user/someuser/DEPARTMENTS
drwxr-xr-x   - someuser somegrp       0 2010-04-27 17:15 /user/someuser/OFFICE_SUPPLIES