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.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 --all-tables
(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 tool.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
