mclient - the MonetDB command-line tool


mclient [ options ] [ file or database [ file ... ] ]
mclient --help


MonetDB is a database management system that is developed from a main-memory perspective with use of a fully decomposed storage model, automatic index management, extensibility of data types and search accelerators, and an SQL front end.

Mclient is the command-line interface to the MonetDB server.

If the --statement=query (-s query) option is given, the query is executed. If any files are listed after the options, queries are read from the files and executed. The special filename - refers to standard input. Note that if there is both a --statement option and filename arguments, the query given with --statement is executed first. If no --statement option is given and no files are specified on the command line, mclient reads queries from standard input.

When reading from standard input, if standard input is a terminal or if the --interactive (-i) option is given, mclient interprets lines starting with \ (backslash) specially. See the section BACKSLASH COMMANDS below.

Before mclient starts parsing command line options, it reads a configuration file. If the environment variable DOTMONETDBFILE is set and not empty, it reads the file pointed to by that variable. If set but empty, no configuration file is read. If unset, mclient first looks for a file .monetdb in the current working directory, and if that doesn't exist, it looks for a file monetdb in the XDG configuration directory ($XDG_CONFIG_HOME which defaults to $HOME/.config if not set), and finally for a file .monetdb in the current user's home directory. This file can contain defaults for the flags user, password, language, database, save_history, format, host, port, and width. For example, an entry in a .monetdb file that sets the default language for mclient to mal looks like this: language=mal. To disable reading the .monetdb file, set the variable DOTMONETDBFILE to the empty string in the environment.


General Options

--help (-?)

Print usage information and exit.

--version (-v)

Print version information and exit.

--encoding=encoding (-E encoding)

Specify the character encoding of the input. The option applies to both the standard input of mclient and to the argument of the --statement (-s) option but not to the contents of files specified on the command line (except for - which refers to standard input) or files specified using the \< command (those must be encoded using UTF-8). The default encoding is taken from the locale.

--language=language (-l language)

Specify the query language. The following languages are recognized: mal and sql. A unique prefix suffices. When the --language option is omitted, the default of sql is assumed.

--database=database (-d database)

Specify the name or URI of the database to connect to. The -d can be omitted if an equally named file does not exist in the current directory. As such, the first non-option argument will be interpreted as database to connect to if the argument does not exist as file. Valid URIs are as returned by `monetdb discover`, see monetdb(1), and look like mapi:monetdb://hostname:port/database.

--host=hostname (-h hostname)

Specify the name of the host on which the server runs (default: localhost). When the argument starts with a forward slash (/), host is assumed to be the directory where the UNIX sockets are stored for platforms where these are supported.

--port=portnr (-p portnr)

Specify the portnumber of the server (default: 50000).

--interactive (-i)

When reading from standard input, interpret lines starting with \ (backslash) specially. See the section BACKSLASH COMMANDS below.

--timer=timermode (-t timermode)

The timer command controls the format of the time reported for queries. The default mode is none which turns off timing reporting. The timer mode clock reports the client-side wall-clock time ("clk") in a human-friendly format. The timer mode performance reports client-side wall-clock time ("clk") as well as detailed server-side timings, all in milliseconds (ms): the time to parse the SQL query, optimize the logical relational plan and create the initial physical (MAL) plan ("sql"); the time to optimize the physical (MAL) plan ("opt"); the time to execute the physical (MAL) plan ("run"). All timings are reported on stderr.
Note that the client-measured wall-clock time is reported per query only when options --interactive or --echo are used, because only then does mclient send individual lines (statements) of the SQL script to the server. Otherwise, when mclient sends the SQL script in large(r) batch(es), only the total wall-clock time per batch is measured and reported. The server-measured detailed performance timings are always measured and reported per query.

--user=user (-u user)

Specify the user to connect as. If this flag is absent, the client will ask for a user name, unless a default was found in the .monetdb or $DOTMONETDBFILE file.

--format=format (-f format)

Specify the output format. The possible values are sql, expanded, x, csv, csv-noquote, tab, raw, xml, trash, and rowcount. csv is comma-separated values; csv-noquote is comma-separated values without escaping any quotes; tab is tab-separated values; raw is no special formatting (data is dumped the way the server sends it to the client); sql is a pretty format which is meant for human consumption where columns are clearly shown; expanded and x are synonyms and are another pretty format meant for human consumption where column values are printed in full and below each other; xml is a valid (in the XML sense) document; trash does not render any output, enabling performance measurements free of any output rendering/serialization costs; and rowcount is a variation on trash where only the number of affected rows is printed. Normal csv and tab formatting will use double quotes around any fields that contain double quotes, white space or the separator. The csv-noquote format will prevent that and dump the contents of the field without any interpretation. In addition to plain csv, two other forms are possible. csv=c uses c as column separator; csv+c uses c as column separator and produces a single header line in addition to the data.

--echo (-e)

Echo the query. Note that using this option slows down processing.

--history (-H)

If compiled with the readline(3) library, load and save the command line history (default off).

--log=logfile (-L logfile)

Save client/server interaction in the specified file.

--statement=stmt (-s stmt)

Execute the specified query. The query is run before any queries from files specified on the command line are run.

--timezone (-z)

Do not tell the client's timezone to the server.

--Xdebug (-X)

Trace network interaction between mclient and the server.

--pager=cmd (-| cmd)

Send query output through the specified cmd. One cmd is started for each query. Note that the | will have to be quoted or else the shell will interpret it.

SQL Options

--null=nullstr (-n nullstr)

Set the string to be used as NULL representation when using the sql, csv, or tab output formats. If not used, NULL values are represented by the string "null" in the sql output format, and as the empty string in the csv and tab output formats. Note that an argument is required, so in order to use the empty string, use -n "" (with the space) or --null=.

--autocommit (-a)

Switch autocommit mode off. By default, autocommit mode is on.

--allow-remote (-R)

Allow remote content (URLs) in the COPY INTO table FROM file ON CLIENT ... query. Remote content is retrieved by mclient.

--rows=nr (-r nr)

If specified, query results will be paged by an internal pager at the specified number of lines.

--width=nr (-w nr)

Specify the width of the screen. The default is the (initial) width of the terminal.

--dump (-D)

Create an SQL dump.

--inserts (-N)

Use INSERT INTO statements instead of COPY INTO + CSV values when dumping the data of a table. This option can be used when trying to load data from MonetDB into another database, or when e.g. JDBC applications are used to reload the dump.


General Commands


Show a help message explaining the backslash commands.


Exit mclient.

\< file

Read input from the named file.

\> file

Write output to the named file. If no file is specified, write to standard output.

\| command

Pipe output to the given command. Each query is piped to a new invocation of the command. If no command is given, revert to writing output to standard output.


Show the readline(3) history.

\L file

Log client/server interaction in the given file. If no file is specified, stop logging information.


Trace what mclient is doing. This is mostly for debugging purposes.


Echo the query in SQL formatting mode.

\f format

Use the specified format mode to format the output. Possible modes the same as for the --format (-f) option.

\w width

Set the maximum page width for rendering in the sql formatting mode. If width is -1, the page width is unlimited, when width is 0, use the terminal width. If width is greater than 0, use the given width.

\r rows

Use an internal pager using rows per page. If rows is -1, stop using the internal pager.

SQL Commands


Dump the complete database. This is equivalent to using the program msqldump(1).

\D table

Dump the given table.


Alias for \dvt.


List database objects of the given type. Multiple type specifiers can be used at the same time. The specifiers S, t, v, s, f and n stand for System, table, view, sequence, function and schema respectively. Note that S simply switches on viewing system catalog objects, which is orthogonal to the other specifiers.

\d[Stvsfn]+ object

Describe the given object in the database using SQL statements that reconstruct the object. The same specifiers as above can be used, following the same rules. When no specifiers are given, vt is assumed. The object can be given with or without a schema, separated by a dot. The object name can contain the wildcard characters * and _ that represent zero or more, and exactly one character respectively. An object name is converted to lowercase, unless the object name is quoted by double quotes ("). Examples of this, are e.g. *.mytable, tabletype*, or "myschema.FOO". Note that wildcard characters do not work in quoted objects. Quoting follows SQL quoting rules. Arbitrary parts can be quoted, and two quotes following each other in a quoted string represent the quote itself.


Enable auto commit mode.


Disable auto commit mode.


Efficiently import data from a CSV (comma-separated values) file into a table. The file must be readable by the server. $file is the absolute path name of the file, $table is the name of the table, $db is the name of the database.

mclient -d $db -s "COPY INTO $table FROM '$file' USING DELIMITERS ',',E'\\n','\"'"

Efficiently import data from a CSV file into a table when the file is to be read by mclient (e.g. the server has no access to the file). $file is the (absolute or relative) path name of the file, $table is the name of the table, $db is the name of the database.

mclient -d $db -s "COPY INTO $table FROM STDIN USING DELIMITERS ',',E'\\n','\"'" - < $file

Note that in this latter case, if a count of records is supplied, it should be at least as large as the number of records actually present in the CSV file. This, because otherwise the remainder of the file will be interpreted as SQL queries.

Another, easier method to have the client read the file content is as follows:

mclient -d $db -s "COPY INTO $table FROM '$file' ON CLIENT USING DELIMITERS ',',E'\\n',\"'"

In this case the value of $file can be a path name relative to the directory in which mclient was started. If, in addition, the option --allow-remote is passed to mclient, the $file in the above query can also be a URL. It then has to have the form schema://string, e.g.,

See for more information about the COPY INTO query.


msqldump(1), mserver5(1)