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Apache Tajo Shell

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5 May 2014


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Tajo Shell (TSQL)

Synopsis

bin/tsql [options] [database name]

If a database_name is given, tsql connects to the database at startup time. Otherwise, tsql connects to default database.

Options

  • -c "quoted sql" : Execute quoted sql statements, and then the shell will exist.
  • -f filename (--file filename) : Use the file named filename as the source of commands instead of interactive shell.
  • -h hostname (--host hostname) : Specifies the host name of the machine on which the Tajo master is running.
  • -p port (--port port) : Specifies the TCP port. If it is not set, the port will be 26002 in default.

Entering tsql shell

If the hostname and the port num are not given, tsql will try to connect the Tajo master specified in ${TAJO_HOME}/conf/tajo-site.xml.

bin/tsql

default>

If you want to connect a specified TajoMaster, you should use ‘-h’ and (or) ‘p’ options as follows:

bin/tsql -h localhost -p 9004

default>

The prompt indicates the current database.

Meta Commands

In tsql, anything command that begins with an unquoted backslash (‘’) is a tsql meta-command that is processed by tsql itself.

In the current implementation, there are meta commands as follows:

default> \?

General
  \copyright  show Apache License 2.0
  \version    show Tajo version
  \?          show help
  \q          quit tsql


Informational
  \l           list databases
  \c           show current database
  \c [DBNAME]  connect to new database
  \d           list tables
  \d [TBNAME]  describe table
  \df          list functions
  \df NAME     describe function


Variables
  \set [[NAME] [VALUE]  set session variable or list session variables
  \unset NAME           unset session variable


Documentations
  tsql guide        http://tajo.apache.org/docs/0.8.0/cli.html
  Query language    http://tajo.apache.org/docs/0.8.0/sql_language.html
  Functions         http://tajo.apache.org/docs/0.8.0/functions.html
  Backup & restore  http://tajo.apache.org/docs/0.8.0/backup_and_restore.html
  Configuration     http://tajo.apache.org/docs/0.8.0/configuration.html

Basic usages

\l command shows a list of all databases.

default> \l
default
tpch
work1
default>

\d command shows a list of tables in the current database as follows.

default> d customer lineitem nation orders part partsupp region supplier

\d [table name] command also shows a table description.

default> d orders

table name: orders table path: hdfs:/xxx/xxx/tpch/orders store type: CSV number of rows: 0 volume (bytes): 172.0 MB schema: o_orderkey INT8 o_custkey INT8 o_orderstatus TEXT o_totalprice FLOAT8 o_orderdate TEXT o_orderpriority TEXT o_clerk TEXT o_shippriority INT4 o_comment TEXT

The prompt default> indicates the current database. Basically, all SQL statements and meta commands work in the current database. Also, you can change the current database with \c command.

default> \c work1
You are now connected to database "test" as user "hyunsik".
work1>

Session Variables

Each client connection to TajoMaster creates a unique session, and the client and TajoMaster uses the session until disconnect. A session provides session variables which are used for various configs per session.

tsql provides the meta command \set to manipulate session variables. Just \set command shows all session variables.

default> \set
'name1'='val1'
'name2'='val2'
'name3'='val3'
 ...

\set key val will set the session variable named key with the value val.

default> \set
'CURRENT_DATABASE'='default'

default> \set key1 val1

default> \set
'CURRENT_DATABASE'='default'
'key1'='val1'

Also, \unset key will unset the session variable named key.


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