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From "Aaron Kimball (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-5815) Sqoop: A database import tool for Hadoop
Date Thu, 14 May 2009 16:08:45 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-5815?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12709453#action_12709453

Aaron Kimball commented on HADOOP-5815:

Contrib test failures are unrelated (streaming).

> Sqoop: A database import tool for Hadoop
> ----------------------------------------
>                 Key: HADOOP-5815
>                 URL: https://issues.apache.org/jira/browse/HADOOP-5815
>             Project: Hadoop Core
>          Issue Type: New Feature
>            Reporter: Aaron Kimball
>            Assignee: Aaron Kimball
>         Attachments: HADOOP-5815.2.patch, HADOOP-5815.patch
> Overview:
> Sqoop is a tool designed to help users import existing relational databases into their
Hadoop clusters. Sqoop uses JDBC to connect to a database, examine the schema for tables,
and auto-generate the necessary classes to import data into HDFS. It then instantiates a MapReduce
job to read the table from the database via the DBInputFormat (JDBC-based InputFormat). The
table is read into a set of files loaded into HDFS. Both SequenceFile and text-based targets
are supported.
> Longer term, Sqoop will support automatic connectivity to Hive, with the ability to load
data files directly into the Hive warehouse directory, and also to inject the appropriate
table definition into the metastore.
> Some more specifics:
> Sqoop is a program implemented as a contrib module. Its frontend is invoked through "bin/hadoop
jar sqoop.jar ..." and allows you to connect to arbitrary JDBC databases and extract their
tables into files in HDFS. The underlying implementation utilizes the JDBC interface of HADOOP-2536
(DBInputFormat). The DBWritable implementation needed to extract a table is generated by this
tool, based on the types of the columns seen in the table. Sqoop uses JDBC to examine the
table specification and translate this to the appropriate Java types.
> The generated classes are provided as .java files for the user to reuse. They are also
compiled into a jar and used to run a MapReduce task to perform the data import. This either
results in text files or SequenceFiles in HDFS. In the latter case, these Java classes are
embedded into the SequenceFiles as well.
> The program will extract a specific table from a database, or optionally, all tables.
For a table, it can read all columns, or just a subset. Since HADOOP-2536 requires that a
sorting key be specified for the import task, Sqoop will auto-detect the presence of a primary
key on a table and automatically use it as the sort order; the user can also manually specify
a sorting column.
> Example invocations:
> To import an entire database:
> hadoop jar sqoop.jar org.apache.hadoop.sqoop.Sqoop --connect jdbc:mysql://db.example.com/company
> (Requires that all tables have primary keys)
> To select a single table:
> hadoop jar sqoop.jar org.apache.hadoop.sqoop.Sqoop --connect jdbc:mysql://db.example.com/company
--table employees
> To select a subset of columns from a table:
> hadoop jar sqoop.jar org.apache.hadoop.sqoop.Sqoop --connect jdbc:mysql://db.example.com/company
--table employees --columns "employee_id,first_name,last_name,salary,start_date"
> To explicitly set the sort column, import format, and import destination (the table will
go to /shared/imported_databases/employees):
> hadoop jar sqoop.jar org.apache.hadoop.sqoop.Sqoop --connect jdbc:mysql://db.example.com/company
--table employees --order-by employee_id --warehouse-dir /shared/imported_databases --as-sequencefile
> Sqoop will automatically select the correct JDBC driver class name for HSQLdb and MySQL;
this can also be explicitly set, e.g.:
> hadoop jar sqoop.jar org.apache.hadoop.sqoop.Sqoop --connect jdbc:postgresql://db.example.com/company
--driver org.postgresql.Driver --all-tables
> Testing has been conducted with HSQLDB and MySQL. A set of unit tests covers a great
deal of Sqoop's functionality, and this tool has been used in practice at Cloudera and with
a few other early test users on "real" databases.
> A readme file is included in the patch which contains documentation on how to use the

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