psql

psql

1

Application

psql

PostgreSQL

interactive terminal

psql

option

dbname

username

Description
===========

psql is a terminal-based front-end to PostgreSQL. It enables you to type
in queries interactively, issue them to PostgreSQL, and see the query
results. Alternatively, input can be from a file or from command line
arguments. In addition, psql provides a number of meta-commands and
various shell-like features to facilitate writing scripts and automating
a wide variety of tasks.

Options {#r1-app-psql-3}
=======

`-a`; `--echo-all`

:   Print all nonempty input lines to standard output as they are read.
    (This does not apply to lines read interactively.) This is
    equivalent to setting the variable `ECHO` to `all`.

`-A`; `--no-align`

:   Switches to unaligned output mode. (The default output mode is
    `aligned`.) This is equivalent to `\pset format unaligned`.

`-b`; `--echo-errors`

:   Print failed SQL commands to standard error output. This is
    equivalent to setting the variable `ECHO` to `errors`.

`-c command`; `--command=command`

:   Specifies that psql is to execute the given command string, command.
    This option can be repeated and combined in any order with the `-f`
    option. When either `-c` or `-f` is specified, psql does not read
    commands from standard input; instead it terminates after processing
    all the `-c` and `-f` options in sequence.

    command must be either a command string that is completely parsable
    by the server (i.e., it contains no psql-specific features), or a
    single backslash command. Thus you cannot mix SQL and psql
    meta-commands within a `-c` option. To achieve that, you could use
    repeated `-c` options or pipe the string into psql, for example:

        psql -c '\x' -c 'SELECT * FROM foo;'

    or

        echo '\x \\ SELECT * FROM foo;' | psql

    (`\\` is the separator meta-command.)

    Each SQL command string passed to `-c` is sent to the server as a
    single request. Because of this, the server executes it as a single
    transaction even if the string contains multiple SQL commands,
    unless there are explicit `BEGIN`/`COMMIT` commands included in the
    string to divide it into multiple transactions. (See
    [???](#protocol-flow-multi-statement) for more details about how the
    server handles multi-query strings.)

    If having several commands executed in one transaction is not
    desired, use repeated `-c` commands or feed multiple commands to
    psql\'s standard input, either using echo as illustrated above, or
    via a shell here-document, for example:

        psql <<EOF
        \x
        SELECT * FROM foo;
        EOF

`--csv`

:   Switches to CSV (Comma-Separated Values) output mode. This is
    equivalent to `\pset format csv`.

`-d dbname`; `--dbname=dbname`

:   Specifies the name of the database to connect to. This is equivalent
    to specifying dbname as the first non-option argument on the command
    line. The dbname can be a [connection string](#libpq-connstring). If
    so, connection string parameters will override any conflicting
    command line options.

`-e`; `--echo-queries`

:   Copy all SQL commands sent to the server to standard output as well.
    This is equivalent to setting the variable `ECHO` to `queries`.

`-E`; `--echo-hidden`

:   Echo the actual queries generated by `\d` and other backslash
    commands. You can use this to study psql\'s internal operations.
    This is equivalent to setting the variable `ECHO_HIDDEN` to `on`.

`-f filename`; `--file=filename`

:   Read commands from the file filename, rather than standard input.
    This option can be repeated and combined in any order with the `-c`
    option. When either `-c` or `-f` is specified, psql does not read
    commands from standard input; instead it terminates after processing
    all the `-c` and `-f` options in sequence. Except for that, this
    option is largely equivalent to the meta-command `\i`.

    If filename is `-` (hyphen), then standard input is read until an
    EOF indication or `\q` meta-command. This can be used to intersperse
    interactive input with input from files. Note however that Readline
    is not used in this case (much as if `-n` had been specified).

    Using this option is subtly different from writing `psql
          < filename`. In general, both will do what you expect, but
    using `-f` enables some nice features such as error messages with
    line numbers. There is also a slight chance that using this option
    will reduce the start-up overhead. On the other hand, the variant
    using the shell\'s input redirection is (in theory) guaranteed to
    yield exactly the same output you would have received had you
    entered everything by hand.

`-F separator`; `--field-separator=separator`

:   Use separator as the field separator for unaligned output. This is
    equivalent to `\pset fieldsep` or `\f`.

`-h hostname`; `--host=hostname`

:   Specifies the host name of the machine on which the server is
    running. If the value begins with a slash, it is used as the
    directory for the Unix-domain socket.

`-H`; `--html`

:   Switches to HTML output mode. This is equivalent to
    `\pset format html` or the `\H` command.

`-l`; `--list`

:   List all available databases, then exit. Other non-connection
    options are ignored. This is similar to the meta-command `\list`.

    When this option is used, psql will connect to the database
    `postgres`, unless a different database is named on the command line
    (option `-d` or non-option argument, possibly via a service entry,
    but not via an environment variable).

`-L filename`; `--log-file=filename`

:   Write all query output into file filename, in addition to the normal
    output destination.

`-n`; `--no-readline`

:   Do not use Readline for line editing and do not use the command
    history (see [refsect3\_title](#app-psql-readline) below).

`-o filename`; `--output=filename`

:   Put all query output into file filename. This is equivalent to the
    command `\o`.

`-p port`; `--port=port`

:   Specifies the TCP port or the local Unix-domain socket file
    extension on which the server is listening for connections. Defaults
    to the value of the PGPORT environment variable or, if not set, to
    the port specified at compile time, usually 5432.

`-P assignment`; `--pset=assignment`

:   Specifies printing options, in the style of `\pset`. Note that here
    you have to separate name and value with an equal sign instead of a
    space. For example, to set the output format to LaTeX, you could
    write `-P format=latex`.

`-q`; `--quiet`

:   Specifies that psql should do its work quietly. By default, it
    prints welcome messages and various informational output. If this
    option is used, none of this happens. This is useful with the `-c`
    option. This is equivalent to setting the variable `QUIET` to `on`.

`-R separator`; `--record-separator=separator`

:   Use separator as the record separator for unaligned output. This is
    equivalent to `\pset recordsep`.

`-s`; `--single-step`

:   Run in single-step mode. That means the user is prompted before each
    command is sent to the server, with the option to cancel execution
    as well. Use this to debug scripts.

`-S`; `--single-line`

:   Runs in single-line mode where a newline terminates an SQL command,
    as a semicolon does.

    > **Note**
    >
    > This mode is provided for those who insist on it, but you are not
    > necessarily encouraged to use it. In particular, if you mix SQL
    > and meta-commands on a line the order of execution might not
    > always be clear to the inexperienced user.

`-t`; `--tuples-only`

:   Turn off printing of column names and result row count footers, etc.
    This is equivalent to `\t` or `\pset tuples_only`.

`-T table_options`; `--table-attr=table_options`

:   Specifies options to be placed within the HTML table tag. See
    `\pset tableattr` for details.

`-U username`; `--username=username`

:   Connect to the database as the user username instead of the default.
    (You must have permission to do so, of course.)

`-v assignment`; `--set=assignment`; `--variable=assignment`

:   Perform a variable assignment, like the `\set` meta-command. Note
    that you must separate name and value, if any, by an equal sign on
    the command line. To unset a variable, leave off the equal sign. To
    set a variable with an empty value, use the equal sign but leave off
    the value. These assignments are done during command line
    processing, so variables that reflect connection state will get
    overwritten later.

`-V`; `--version`

:   Print the psql version and exit.

`-w`; `--no-password`

:   Never issue a password prompt. If the server requires password
    authentication and a password is not available from other sources
    such as a `.pgpass` file, the connection attempt will fail. This
    option can be useful in batch jobs and scripts where no user is
    present to enter a password.

    Note that this option will remain set for the entire session, and so
    it affects uses of the meta-command `\connect` as well as the
    initial connection attempt.

`-W`; `--password`

:   Force psql to prompt for a password before connecting to a database,
    even if the password will not be used.

    If the server requires password authentication and a password is not
    available from other sources such as a `.pgpass` file, psql will
    prompt for a password in any case. However, psql will waste a
    connection attempt finding out that the server wants a password. In
    some cases it is worth typing `-W` to avoid the extra connection
    attempt.

    Note that this option will remain set for the entire session, and so
    it affects uses of the meta-command `\connect` as well as the
    initial connection attempt.

`-x`; `--expanded`

:   Turn on the expanded table formatting mode. This is equivalent to
    `\x` or `\pset expanded`.

`-X,`; `--no-psqlrc`

:   Do not read the start-up file (neither the system-wide `psqlrc` file
    nor the user\'s `~/.psqlrc` file).

`-z`; `--field-separator-zero`

:   Set the field separator for unaligned output to a zero byte. This is
    equivalent to `\pset fieldsep_zero`.

`-0`; `--record-separator-zero`

:   Set the record separator for unaligned output to a zero byte. This
    is useful for interfacing, for example, with `xargs -0`. This is
    equivalent to `\pset recordsep_zero`.

`-1`; `--single-transaction`

:   This option can only be used in combination with one or more `-c`
    and/or `-f` options. It causes psql to issue a `BEGIN` command
    before the first such option and a `COMMIT` command after the last
    one, thereby wrapping all the commands into a single transaction.
    This ensures that either all the commands complete successfully, or
    no changes are applied.

    If the commands themselves contain `BEGIN`, `COMMIT`, or `ROLLBACK`,
    this option will not have the desired effects. Also, if an
    individual command cannot be executed inside a transaction block,
    specifying this option will cause the whole transaction to fail.

`-?`; `--help[=topic]`

:   Show help about psql and exit. The optional topic parameter
    (defaulting to `options`) selects which part of psql is explained:
    `commands` describes psql\'s backslash commands; `options` describes
    the command-line options that can be passed to psql; and `variables`
    shows help about psql configuration variables.

Exit Status
===========

psql returns 0 to the shell if it finished normally, 1 if a fatal error
of its own occurs (e.g., out of memory, file not found), 2 if the
connection to the server went bad and the session was not interactive,
and 3 if an error occurred in a script and the variable `ON_ERROR_STOP`
was set.

Usage
=====

Connecting to a Database {#r2-app-psql-connecting}
------------------------

psql is a regular PostgreSQL client application. In order to connect to
a database you need to know the name of your target database, the host
name and port number of the server, and what user name you want to
connect as. psql can be told about those parameters via command line
options, namely `-d`, `-h`, `-p`, and `-U` respectively. If an argument
is found that does not belong to any option it will be interpreted as
the database name (or the user name, if the database name is already
given). Not all of these options are required; there are useful
defaults. If you omit the host name, psql will connect via a Unix-domain
socket to a server on the local host, or via TCP/IP to `localhost` on
machines that don\'t have Unix-domain sockets. The default port number
is determined at compile time. Since the database server uses the same
default, you will not have to specify the port in most cases. The
default user name is your operating-system user name, as is the default
database name. Note that you cannot just connect to any database under
any user name. Your database administrator should have informed you
about your access rights.

When the defaults aren\'t quite right, you can save yourself some typing
by setting the environment variables PGDATABASE, PGHOST, PGPORT and/or
PGUSER to appropriate values. (For additional environment variables, see
[???](#libpq-envars).) It is also convenient to have a `~/.pgpass` file
to avoid regularly having to type in passwords. See [???](#libpq-pgpass)
for more information.

An alternative way to specify connection parameters is in a `conninfo`
string or a URI, which is used instead of a database name. This
mechanism give you very wide control over the connection. For example:

    $ psql "service=myservice sslmode=require"
    $ psql postgresql://dbmaster:5433/mydb?sslmode=require

This way you can also use LDAP for connection parameter lookup as
described in [???](#libpq-ldap). See [???](#libpq-paramkeywords) for
more information on all the available connection options.

If the connection could not be made for any reason (e.g., insufficient
privileges, server is not running on the targeted host, etc.), psql will
return an error and terminate.

If both standard input and standard output are a terminal, then psql
sets the client encoding to "auto", which will detect the appropriate
client encoding from the locale settings (LC\_CTYPE environment variable
on Unix systems). If this doesn\'t work out as expected, the client
encoding can be overridden using the environment variable
PGCLIENTENCODING.

Entering SQL Commands {#r2-app-psql-4}
---------------------

In normal operation, psql provides a prompt with the name of the
database to which psql is currently connected, followed by the string
`=>`. For example:

    $ psql testdb
    psql (VERSION)
    Type "help" for help.

    testdb=>

At the prompt, the user can type in SQL commands. Ordinarily, input
lines are sent to the server when a command-terminating semicolon is
reached. An end of line does not terminate a command. Thus commands can
be spread over several lines for clarity. If the command was sent and
executed without error, the results of the command are displayed on the
screen.

If untrusted users have access to a database that has not adopted a
[secure schema usage pattern](#ddl-schemas-patterns), begin your session
by removing publicly-writable schemas from `search_path`. One can add
`options=-csearch_path=` to the connection string or issue
`SELECT pg_catalog.set_config('search_path', '',
    false)` before other SQL commands. This consideration is not
specific to psql; it applies to every interface for executing arbitrary
SQL commands.

Whenever a command is executed, psql also polls for asynchronous
notification events generated by [`LISTEN`](#sql-listen) and
[`NOTIFY`](#sql-notify).

While C-style block comments are passed to the server for processing and
removal, SQL-standard comments are removed by psql.

Meta-Commands {#app-psql-meta-commands}
-------------

Anything you enter in psql that begins with an unquoted backslash is a
psql meta-command that is processed by psql itself. These commands make
psql more useful for administration or scripting. Meta-commands are
often called slash or backslash commands.

The format of a psql command is the backslash, followed immediately by a
command verb, then any arguments. The arguments are separated from the
command verb and each other by any number of whitespace characters.

To include whitespace in an argument you can quote it with single
quotes. To include a single quote in an argument, write two single
quotes within single-quoted text. Anything contained in single quotes is
furthermore subject to C-like substitutions for `\n` (new line), `\t`
(tab), `\b` (backspace), `\r` (carriage return), `\f` (form feed),
`\`digits (octal), and `\x`digits (hexadecimal). A backslash preceding
any other character within single-quoted text quotes that single
character, whatever it is.

If an unquoted colon (`:`) followed by a psql variable name appears
within an argument, it is replaced by the variable\'s value, as
described in [SQL Interpolation](#app-psql-interpolation) below. The
forms `:'variable_name'` and `:"variable_name"` described there work as
well. The `:{?variable_name}` syntax allows testing whether a variable
is defined. It is substituted by TRUE or FALSE. Escaping the colon with
a backslash protects it from substitution.

Within an argument, text that is enclosed in backquotes (`` ` ``) is
taken as a command line that is passed to the shell. The output of the
command (with any trailing newline removed) replaces the backquoted
text. Within the text enclosed in backquotes, no special quoting or
other processing occurs, except that appearances of `:variable_name`
where variable\_name is a psql variable name are replaced by the
variable\'s value. Also, appearances of `:'variable_name'` are replaced
by the variable\'s value suitably quoted to become a single shell
command argument. (The latter form is almost always preferable, unless
you are very sure of what is in the variable.) Because carriage return
and line feed characters cannot be safely quoted on all platforms, the
`:'variable_name'` form prints an error message and does not substitute
the variable value when such characters appear in the value.

Some commands take an SQL identifier (such as a table name) as argument.
These arguments follow the syntax rules of SQL: Unquoted letters are
forced to lowercase, while double quotes (`"`) protect letters from case
conversion and allow incorporation of whitespace into the identifier.
Within double quotes, paired double quotes reduce to a single double
quote in the resulting name. For example, `FOO"BAR"BAZ` is interpreted
as `fooBARbaz`, and `"A weird"" name"` becomes `A weird"
    name`.

Parsing for arguments stops at the end of the line, or when another
unquoted backslash is found. An unquoted backslash is taken as the
beginning of a new meta-command. The special sequence `\\` (two
backslashes) marks the end of arguments and continues parsing SQL
commands, if any. That way SQL and psql commands can be freely mixed on
a line. But in any case, the arguments of a meta-command cannot continue
beyond the end of the line.

Many of the meta-commands act on the current query buffer. This is
simply a buffer holding whatever SQL command text has been typed but not
yet sent to the server for execution. This will include previous input
lines as well as any text appearing before the meta-command on the same
line.

The following meta-commands are defined:

`\a`

:   If the current table output format is unaligned, it is switched to
    aligned. If it is not unaligned, it is set to unaligned. This
    command is kept for backwards compatibility. See `\pset` for a more
    general solution.

`\c` or `\connect [ -reuse-previous=on|off ] [ dbname [ username ] [ host ] [ port ] | conninfo ]`

:   Establishes a new connection to a PostgreSQL server. The connection
    parameters to use can be specified either using a positional syntax
    (one or more of database name, user, host, and port), or using a
    conninfo connection string as detailed in [???](#libpq-connstring).
    If no arguments are given, a new connection is made using the same
    parameters as before.

    Specifying any of dbname, username, host or port as `-` is
    equivalent to omitting that parameter.

    The new connection can re-use connection parameters from the
    previous connection; not only database name, user, host, and port,
    but other settings such as sslmode. By default, parameters are
    re-used in the positional syntax, but not when a conninfo string is
    given. Passing a first argument of `-reuse-previous=on` or
    `-reuse-previous=off` overrides that default. If parameters are
    re-used, then any parameter not explicitly specified as a positional
    parameter or in the conninfo string is taken from the existing
    connection\'s parameters. An exception is that if the host setting
    is changed from its previous value using the positional syntax, any
    hostaddr setting present in the existing connection\'s parameters is
    dropped. Also, any password used for the existing connection will be
    re-used only if the user, host, and port settings are not changed.
    When the command neither specifies nor reuses a particular
    parameter, the libpq default is used.

    If the new connection is successfully made, the previous connection
    is closed. If the connection attempt fails (wrong user name, access
    denied, etc.), the previous connection will be kept if psql is in
    interactive mode. But when executing a non-interactive script, the
    old connection is closed and an error is reported. That may or may
    not terminate the script; if it does not, all database-accessing
    commands will fail until another `\connect` command is successfully
    executed. This distinction was chosen as a user convenience against
    typos on the one hand, and a safety mechanism that scripts are not
    accidentally acting on the wrong database on the other hand. Note
    that whenever a `\connect` command attempts to re-use parameters,
    the values re-used are those of the last successful connection, not
    of any failed attempts made subsequently. However, in the case of a
    non-interactive `\connect` failure, no parameters are allowed to be
    re-used later, since the script would likely be expecting the values
    from the failed `\connect` to be re-used.

    Examples:

        => \c mydb myuser host.dom 6432
        => \c service=foo
        => \c "host=localhost port=5432 dbname=mydb connect_timeout=10 sslmode=disable"
        => \c -reuse-previous=on sslmode=require    -- changes only sslmode
        => \c postgresql://tom@localhost/mydb?application_name=myapp

`\C [ title ]`

:   Sets the title of any tables being printed as the result of a query
    or unset any such title. This command is equivalent to
    `\pset title title`. (The name of this command derives from
    "caption", as it was previously only used to set the caption in an
    HTML table.)

`\cd [ directory ]`

:   Changes the current working directory to directory. Without
    argument, changes to the current user\'s home directory.

    > **Tip**
    >
    > To print your current working directory, use `\! pwd`.

`\conninfo`

:   Outputs information about the current database connection.

`\copy { table [ ( column_list ) ] }
        from
        { 'filename' | program 'command' | stdin | pstdin }
        [ [ with ] ( option [, ...] ) ]
        [ where condition ]`; `\copy { table [ ( column_list ) ] | ( query ) }
        to
        { 'filename' | program 'command' | stdout | pstdout }
        [ [ with ] ( option [, ...] ) ]`

:   Performs a frontend (client) copy. This is an operation that runs an
    SQL [`COPY`](#sql-copy) command, but instead of the server reading
    or writing the specified file, psql reads or writes the file and
    routes the data between the server and the local file system. This
    means that file accessibility and privileges are those of the local
    user, not the server, and no SQL superuser privileges are required.

    When `program` is specified, command is executed by psql and the
    data passed from or to command is routed between the server and the
    client. Again, the execution privileges are those of the local user,
    not the server, and no SQL superuser privileges are required.

    For `\copy ... from stdin`, data rows are read from the same source
    that issued the command, continuing until `\.` is read or the stream
    reaches EOF. This option is useful for populating tables in-line
    within an SQL script file. For `\copy ... to stdout`, output is sent
    to the same place as psql command output, and the `COPY count`
    command status is not printed (since it might be confused with a
    data row). To read/write psql\'s standard input or output regardless
    of the current command source or `\o` option, write `from pstdin` or
    `to pstdout`.

    The syntax of this command is similar to that of the SQL
    [`COPY`](#sql-copy) command. All options other than the data
    source/destination are as specified for `COPY`. Because of this,
    special parsing rules apply to the `\copy` meta-command. Unlike most
    other meta-commands, the entire remainder of the line is always
    taken to be the arguments of `\copy`, and neither variable
    interpolation nor backquote expansion are performed in the
    arguments.

    > **Tip**
    >
    > Another way to obtain the same result as `\copy
    >         ... to` is to use the SQL `COPY
    >         ... TO STDOUT` command and terminate it with `\g filename`
    > or `\g |program`. Unlike `\copy`, this method allows the command
    > to span multiple lines; also, variable interpolation and backquote
    > expansion can be used.

    > **Tip**
    >
    > These operations are not as efficient as the SQL `COPY` command
    > with a file or program data source or destination, because all
    > data must pass through the client/server connection. For large
    > amounts of data the SQL command might be preferable.

`\copyright`

:   Shows the copyright and distribution terms of PostgreSQL.

`\crosstabview [
            colV
            [ colH
            [ colD
            [ sortcolH
            ] ] ] ] `

:   Executes the current query buffer (like `\g`) and shows the results
    in a crosstab grid. The query must return at least three columns.
    The output column identified by colV becomes a vertical header and
    the output column identified by colH becomes a horizontal header.
    colD identifies the output column to display within the grid.
    sortcolH identifies an optional sort column for the horizontal
    header.

    Each column specification can be a column number (starting at 1) or
    a column name. The usual SQL case folding and quoting rules apply to
    column names. If omitted, colV is taken as column 1 and colH as
    column 2. colH must differ from colV. If colD is not specified, then
    there must be exactly three columns in the query result, and the
    column that is neither colV nor colH is taken to be colD.

    The vertical header, displayed as the leftmost column, contains the
    values found in column colV, in the same order as in the query
    results, but with duplicates removed.

    The horizontal header, displayed as the first row, contains the
    values found in column colH, with duplicates removed. By default,
    these appear in the same order as in the query results. But if the
    optional sortcolH argument is given, it identifies a column whose
    values must be integer numbers, and the values from colH will appear
    in the horizontal header sorted according to the corresponding
    sortcolH values.

    Inside the crosstab grid, for each distinct value `x` of colH and
    each distinct value `y` of colV, the cell located at the
    intersection `(x,y)` contains the value of the `colD` column in the
    query result row for which the value of colH is `x` and the value of
    colV is `y`. If there is no such row, the cell is empty. If there
    are multiple such rows, an error is reported.

`\d[S+] [ pattern ]`

:   For each relation (table, view, materialized view, index, sequence,
    or foreign table) or composite type matching the pattern, show all
    columns, their types, the tablespace (if not the default) and any
    special attributes such as `NOT NULL` or defaults. Associated
    indexes, constraints, rules, and triggers are also shown. For
    foreign tables, the associated foreign server is shown as well.
    ("Matching the pattern" is defined in [Patterns](#app-psql-patterns)
    below.)

    For some types of relation, `\d` shows additional information for
    each column: column values for sequences, indexed expressions for
    indexes, and foreign data wrapper options for foreign tables.

    The command form `\d+` is identical, except that more information is
    displayed: any comments associated with the columns of the table are
    shown, as is the presence of OIDs in the table, the view definition
    if the relation is a view, a non-default [replica
    identity](#sql-altertable-replica-identity) setting and the [access
    method](#sql-create-access-method) name if the relation has an
    access method.

    By default, only user-created objects are shown; supply a pattern or
    the `S` modifier to include system objects.

    > **Note**
    >
    > If `\d` is used without a pattern argument, it is equivalent to
    > `\dtvmsE` which will show a list of all visible tables, views,
    > materialized views, sequences and foreign tables. This is purely a
    > convenience measure.

`\da[S] [ pattern ]`

:   Lists aggregate functions, together with their return type and the
    data types they operate on. If pattern is specified, only aggregates
    whose names match the pattern are shown. By default, only
    user-created objects are shown; supply a pattern or the `S` modifier
    to include system objects.

`\dA[+] [ pattern ]`

:   Lists access methods. If pattern is specified, only access methods
    whose names match the pattern are shown. If `+` is appended to the
    command name, each access method is listed with its associated
    handler function and description.

`\dAc[+]
            [access-method-pattern
              [input-type-pattern]]
          `

:   Lists operator classes (see [???](#xindex-opclass)). If
    access-method-pattern is specified, only operator classes associated
    with access methods whose names match that pattern are listed. If
    input-type-pattern is specified, only operator classes associated
    with input types whose names match that pattern are listed. If `+`
    is appended to the command name, each operator class is listed with
    its associated operator family and owner.

`\dAf[+]
            [access-method-pattern
              [input-type-pattern]]
          `

:   Lists operator families (see [???](#xindex-opfamily)). If
    access-method-pattern is specified, only operator families
    associated with access methods whose names match that pattern are
    listed. If input-type-pattern is specified, only operator families
    associated with input types whose names match that pattern are
    listed. If `+` is appended to the command name, each operator family
    is listed with its owner.

`\dAo[+]
            [access-method-pattern
              [operator-family-pattern]]
          `

:   Lists operators associated with operator families (see
    [???](#xindex-strategies)). If access-method-pattern is specified,
    only members of operator families associated with access methods
    whose names match that pattern are listed. If
    operator-family-pattern is specified, only members of operator
    families whose names match that pattern are listed. If `+` is
    appended to the command name, each operator is listed with its sort
    operator family (if it is an ordering operator).

`\dAp[+]
            [access-method-pattern
              [operator-family-pattern]]
          `

:   Lists support functions associated with operator families (see
    [???](#xindex-support)). If access-method-pattern is specified, only
    functions of operator families associated with access methods whose
    names match that pattern are listed. If operator-family-pattern is
    specified, only functions of operator families whose names match
    that pattern are listed. If `+` is appended to the command name,
    functions are displayed verbosely, with their actual parameter
    lists.

`\db[+] [ pattern ]`

:   Lists tablespaces. If pattern is specified, only tablespaces whose
    names match the pattern are shown. If `+` is appended to the command
    name, each tablespace is listed with its associated options, on-disk
    size, permissions and description.

`\dc[S+] [ pattern ]`

:   Lists conversions between character-set encodings. If pattern is
    specified, only conversions whose names match the pattern are
    listed. By default, only user-created objects are shown; supply a
    pattern or the `S` modifier to include system objects. If `+` is
    appended to the command name, each object is listed with its
    associated description.

`\dconfig[+] [ pattern ]`

:   Lists server configuration parameters and their values. If pattern
    is specified, only parameters whose names match the pattern are
    listed. Without a pattern, only parameters that are set to
    non-default values are listed. (Use `\dconfig *` to see all
    parameters.) If `+` is appended to the command name, each parameter
    is listed with its data type, context in which the parameter can be
    set, and access privileges (if non-default access privileges have
    been granted).

`\dC[+] [ pattern ]`

:   Lists type casts. If pattern is specified, only casts whose source
    or target types match the pattern are listed. If `+` is appended to
    the command name, each object is listed with its associated
    description.

`\dd[S] [ pattern ]`

:   Shows the descriptions of objects of type `constraint`,
    `operator class`, `operator family`, `rule`, and `trigger`. All
    other comments may be viewed by the respective backslash commands
    for those object types.

    `\dd` displays descriptions for objects matching the pattern, or of
    visible objects of the appropriate type if no argument is given. But
    in either case, only objects that have a description are listed. By
    default, only user-created objects are shown; supply a pattern or
    the `S` modifier to include system objects.

    Descriptions for objects can be created with the
    [`COMMENT`](#sql-comment) SQL command.

`\dD[S+] [ pattern ]`

:   Lists domains. If pattern is specified, only domains whose names
    match the pattern are shown. By default, only user-created objects
    are shown; supply a pattern or the `S` modifier to include system
    objects. If `+` is appended to the command name, each object is
    listed with its associated permissions and description.

`\ddp [ pattern ]`

:   Lists default access privilege settings. An entry is shown for each
    role (and schema, if applicable) for which the default privilege
    settings have been changed from the built-in defaults. If pattern is
    specified, only entries whose role name or schema name matches the
    pattern are listed.

    The [`ALTER DEFAULT
            PRIVILEGES`](#sql-alterdefaultprivileges) command is used to
    set default access privileges. The meaning of the privilege display
    is explained in [???](#ddl-priv).

`\dE[S+] [ pattern ]`; `\di[S+] [ pattern ]`; `\dm[S+] [ pattern ]`; `\ds[S+] [ pattern ]`; `\dt[S+] [ pattern ]`; `\dv[S+] [ pattern ]`

:   In this group of commands, the letters `E`, `i`, `m`, `s`, `t`, and
    `v` stand for foreign table, index, materialized view, sequence,
    table, and view, respectively. You can specify any or all of these
    letters, in any order, to obtain a listing of objects of these
    types. For example, `\dti` lists tables and indexes. If `+` is
    appended to the command name, each object is listed with its
    persistence status (permanent, temporary, or unlogged), physical
    size on disk, and associated description if any. If pattern is
    specified, only objects whose names match the pattern are listed. By
    default, only user-created objects are shown; supply a pattern or
    the `S` modifier to include system objects.

`\des[+] [ pattern ]`

:   Lists foreign servers (mnemonic: "external servers"). If pattern is
    specified, only those servers whose name matches the pattern are
    listed. If the form `\des+` is used, a full description of each
    server is shown, including the server\'s access privileges, type,
    version, options, and description.

`\det[+] [ pattern ]`

:   Lists foreign tables (mnemonic: "external tables"). If pattern is
    specified, only entries whose table name or schema name matches the
    pattern are listed. If the form `\det+` is used, generic options and
    the foreign table description are also displayed.

`\deu[+] [ pattern ]`

:   Lists user mappings (mnemonic: "external users"). If pattern is
    specified, only those mappings whose user names match the pattern
    are listed. If the form `\deu+` is used, additional information
    about each mapping is shown.

    > **Caution**
    >
    > `\deu+` might also display the user name and password of the
    > remote user, so care should be taken not to disclose them.

`\dew[+] [ pattern ]`

:   Lists foreign-data wrappers (mnemonic: "external wrappers"). If
    pattern is specified, only those foreign-data wrappers whose name
    matches the pattern are listed. If the form `\dew+` is used, the
    access privileges, options, and description of the foreign-data
    wrapper are also shown.

`\df[anptwS+] [ pattern [ arg_pattern ... ] ]`

:   Lists functions, together with their result data types, argument
    data types, and function types, which are classified as "agg"
    (aggregate), "normal", "procedure", "trigger", or "window". To
    display only functions of specific type(s), add the corresponding
    letters `a`, `n`, `p`, `t`, or `w` to the command. If pattern is
    specified, only functions whose names match the pattern are shown.
    Any additional arguments are type-name patterns, which are matched
    to the type names of the first, second, and so on arguments of the
    function. (Matching functions can have more arguments than what you
    specify. To prevent that, write a dash `-` as the last
    arg\_pattern.) By default, only user-created objects are shown;
    supply a pattern or the `S` modifier to include system objects. If
    the form `\df+` is used, additional information about each function
    is shown, including volatility, parallel safety, owner, security
    classification, access privileges, language, source code and
    description.

`\dF[+] [ pattern ]`

:   Lists text search configurations. If pattern is specified, only
    configurations whose names match the pattern are shown. If the form
    `\dF+` is used, a full description of each configuration is shown,
    including the underlying text search parser and the dictionary list
    for each parser token type.

`\dFd[+] [ pattern ]`

:   Lists text search dictionaries. If pattern is specified, only
    dictionaries whose names match the pattern are shown. If the form
    `\dFd+` is used, additional information is shown about each selected
    dictionary, including the underlying text search template and the
    option values.

`\dFp[+] [ pattern ]`

:   Lists text search parsers. If pattern is specified, only parsers
    whose names match the pattern are shown. If the form `\dFp+` is
    used, a full description of each parser is shown, including the
    underlying functions and the list of recognized token types.

`\dFt[+] [ pattern ]`

:   Lists text search templates. If pattern is specified, only templates
    whose names match the pattern are shown. If the form `\dFt+` is
    used, additional information is shown about each template, including
    the underlying function names.

`\dg[S+] [ pattern ]`

:   Lists database roles. (Since the concepts of "users" and "groups"
    have been unified into "roles", this command is now equivalent to
    `\du`.) By default, only user-created roles are shown; supply the
    `S` modifier to include system roles. If pattern is specified, only
    those roles whose names match the pattern are listed. If the form
    `\dg+` is used, additional information is shown about each role;
    currently this adds the comment for each role.

`\dl[+]`

:   This is an alias for `\lo_list`, which shows a list of large
    objects. If `+` is appended to the command name, each large object
    is listed with its associated permissions, if any.

`\dL[S+] [ pattern ]`

:   Lists procedural languages. If pattern is specified, only languages
    whose names match the pattern are listed. By default, only
    user-created languages are shown; supply the `S` modifier to include
    system objects. If `+` is appended to the command name, each
    language is listed with its call handler, validator, access
    privileges, and whether it is a system object.

`\dn[S+] [ pattern ]`

:   Lists schemas (namespaces). If pattern is specified, only schemas
    whose names match the pattern are listed. By default, only
    user-created objects are shown; supply a pattern or the `S` modifier
    to include system objects. If `+` is appended to the command name,
    each object is listed with its associated permissions and
    description, if any.

`\do[S+] [ pattern [ arg_pattern [ arg_pattern ] ] ]`

:   Lists operators with their operand and result types. If pattern is
    specified, only operators whose names match the pattern are listed.
    If one arg\_pattern is specified, only prefix operators whose right
    argument\'s type name matches that pattern are listed. If two
    arg\_patterns are specified, only binary operators whose argument
    type names match those patterns are listed. (Alternatively, write
    `-` for the unused argument of a unary operator.) By default, only
    user-created objects are shown; supply a pattern or the `S` modifier
    to include system objects. If `+` is appended to the command name,
    additional information about each operator is shown, currently just
    the name of the underlying function.

`\dO[S+] [ pattern ]`

:   Lists collations. If pattern is specified, only collations whose
    names match the pattern are listed. By default, only user-created
    objects are shown; supply a pattern or the `S` modifier to include
    system objects. If `+` is appended to the command name, each
    collation is listed with its associated description, if any. Note
    that only collations usable with the current database\'s encoding
    are shown, so the results may vary in different databases of the
    same installation.

`\dp [ pattern ]`

:   Lists tables, views and sequences with their associated access
    privileges. If pattern is specified, only tables, views and
    sequences whose names match the pattern are listed.

    The [`GRANT`](#sql-grant) and [`REVOKE`](#sql-revoke) commands are
    used to set access privileges. The meaning of the privilege display
    is explained in [???](#ddl-priv).

`\dP[itn+] [ pattern ]`

:   Lists partitioned relations. If pattern is specified, only entries
    whose name matches the pattern are listed. The modifiers `t`
    (tables) and `i` (indexes) can be appended to the command, filtering
    the kind of relations to list. By default, partitioned tables and
    indexes are listed.

    If the modifier `n` ("nested") is used, or a pattern is specified,
    then non-root partitioned relations are included, and a column is
    shown displaying the parent of each partitioned relation.

    If `+` is appended to the command name, the sum of the sizes of each
    relation\'s partitions is also displayed, along with the relation\'s
    description. If `n` is combined with `+`, two sizes are shown: one
    including the total size of directly-attached leaf partitions, and
    another showing the total size of all partitions, including
    indirectly attached sub-partitions.

`\drds [ role-pattern [ database-pattern ] ]`

:   Lists defined configuration settings. These settings can be
    role-specific, database-specific, or both. role-pattern and
    database-pattern are used to select specific roles and databases to
    list, respectively. If omitted, or if `*` is specified, all settings
    are listed, including those not role-specific or database-specific,
    respectively.

    The [`ALTER ROLE`](#sql-alterrole) and
    [`ALTER DATABASE`](#sql-alterdatabase) commands are used to define
    per-role and per-database configuration settings.

`\dRp[+] [ pattern ]`

:   Lists replication publications. If pattern is specified, only those
    publications whose names match the pattern are listed. If `+` is
    appended to the command name, the tables and schemas associated with
    each publication are shown as well.

`\dRs[+] [ pattern ]`

:   Lists replication subscriptions. If pattern is specified, only those
    subscriptions whose names match the pattern are listed. If `+` is
    appended to the command name, additional properties of the
    subscriptions are shown.

`\dT[S+] [ pattern ]`

:   Lists data types. If pattern is specified, only types whose names
    match the pattern are listed. If `+` is appended to the command
    name, each type is listed with its internal name and size, its
    allowed values if it is an `enum` type, and its associated
    permissions. By default, only user-created objects are shown; supply
    a pattern or the `S` modifier to include system objects.

`\du[S+] [ pattern ]`

:   Lists database roles. (Since the concepts of "users" and "groups"
    have been unified into "roles", this command is now equivalent to
    `\dg`.) By default, only user-created roles are shown; supply the
    `S` modifier to include system roles. If pattern is specified, only
    those roles whose names match the pattern are listed. If the form
    `\du+` is used, additional information is shown about each role;
    currently this adds the comment for each role.

`\dx[+] [ pattern ]`

:   Lists installed extensions. If pattern is specified, only those
    extensions whose names match the pattern are listed. If the form
    `\dx+` is used, all the objects belonging to each matching extension
    are listed.

`\dX [ pattern ]`

:   Lists extended statistics. If pattern is specified, only those
    extended statistics whose names match the pattern are listed.

    The status of each kind of extended statistics is shown in a column
    named after its statistic kind (e.g. Ndistinct). `defined` means
    that it was requested when creating the statistics, and NULL means
    it wasn\'t requested. You can use pg\_stats\_ext if you\'d like to
    know whether [`ANALYZE`](#sql-analyze) was run and statistics are
    available to the planner.

`\dy[+] [ pattern ]`

:   Lists event triggers. If pattern is specified, only those event
    triggers whose names match the pattern are listed. If `+` is
    appended to the command name, each object is listed with its
    associated description.

`\e` or `\edit` `  filename   line_number  `

:   If filename is specified, the file is edited; after the editor
    exits, the file\'s content is copied into the current query buffer.
    If no filename is given, the current query buffer is copied to a
    temporary file which is then edited in the same fashion. Or, if the
    current query buffer is empty, the most recently executed query is
    copied to a temporary file and edited in the same fashion.

    If you edit a file or the previous query, and you quit the editor
    without modifying the file, the query buffer is cleared. Otherwise,
    the new contents of the query buffer are re-parsed according to the
    normal rules of psql, treating the whole buffer as a single line.
    Any complete queries are immediately executed; that is, if the query
    buffer contains or ends with a semicolon, everything up to that
    point is executed and removed from the query buffer. Whatever
    remains in the query buffer is redisplayed. Type semicolon or `\g`
    to send it, or `\r` to cancel it by clearing the query buffer.

    Treating the buffer as a single line primarily affects
    meta-commands: whatever is in the buffer after a meta-command will
    be taken as argument(s) to the meta-command, even if it spans
    multiple lines. (Thus you cannot make meta-command-using scripts
    this way. Use `\i` for that.)

    If a line number is specified, psql will position the cursor on the
    specified line of the file or query buffer. Note that if a single
    all-digits argument is given, psql assumes it is a line number, not
    a file name.

    > **Tip**
    >
    > See [Environment](#app-psql-environment), below, for how to
    > configure and customize your editor.

`\echo text [ ... ]`

:   Prints the evaluated arguments to standard output, separated by
    spaces and followed by a newline. This can be useful to intersperse
    information in the output of scripts. For example:

        => \echo `date`
        Tue Oct 26 21:40:57 CEST 1999

    If the first argument is an unquoted `-n` the trailing newline is
    not written (nor is the first argument).

    > **Tip**
    >
    > If you use the `\o` command to redirect your query output you
    > might wish to use `\qecho` instead of this command. See also
    > `\warn`.

`\ef  function_description   line_number   `

:   This command fetches and edits the definition of the named function
    or procedure, in the form of a `CREATE OR REPLACE FUNCTION` or
    `CREATE OR REPLACE PROCEDURE` command. Editing is done in the same
    way as for `\edit`. If you quit the editor without saving, the
    statement is discarded. If you save and exit the editor, the updated
    command is executed immediately if you added a semicolon to it.
    Otherwise it is redisplayed; type semicolon or `\g` to send it, or
    `\r` to cancel.

    The target function can be specified by name alone, or by name and
    arguments, for example `foo(integer, text)`. The argument types must
    be given if there is more than one function of the same name.

    If no function is specified, a blank `CREATE FUNCTION` template is
    presented for editing.

    If a line number is specified, psql will position the cursor on the
    specified line of the function body. (Note that the function body
    typically does not begin on the first line of the file.)

    Unlike most other meta-commands, the entire remainder of the line is
    always taken to be the argument(s) of `\ef`, and neither variable
    interpolation nor backquote expansion are performed in the
    arguments.

    > **Tip**
    >
    > See [Environment](#app-psql-environment), below, for how to
    > configure and customize your editor.

`\encoding [ encoding ]`

:   Sets the client character set encoding. Without an argument, this
    command shows the current encoding.

`\errverbose`

:   Repeats the most recent server error message at maximum verbosity,
    as though `VERBOSITY` were set to `verbose` and `SHOW_CONTEXT` were
    set to `always`.

`\ev  view_name   line_number   `

:   This command fetches and edits the definition of the named view, in
    the form of a `CREATE OR REPLACE VIEW` command. Editing is done in
    the same way as for `\edit`. If you quit the editor without saving,
    the statement is discarded. If you save and exit the editor, the
    updated command is executed immediately if you added a semicolon to
    it. Otherwise it is redisplayed; type semicolon or `\g` to send it,
    or `\r` to cancel.

    If no view is specified, a blank `CREATE VIEW` template is presented
    for editing.

    If a line number is specified, psql will position the cursor on the
    specified line of the view definition.

    Unlike most other meta-commands, the entire remainder of the line is
    always taken to be the argument(s) of `\ev`, and neither variable
    interpolation nor backquote expansion are performed in the
    arguments.

`\f [ string ]`

:   Sets the field separator for unaligned query output. The default is
    the vertical bar (`|`). It is equivalent to `\pset fieldsep`.

`\g [ (option=value [...]) ] [ filename ]`; `\g [ (option=value [...]) ] [ |command ]`

:   Sends the current query buffer to the server for execution.

    If parentheses appear after `\g`, they surround a space-separated
    list of option`=`value formatting-option clauses, which are
    interpreted in the same way as `\pset` option value commands, but
    take effect only for the duration of this query. In this list,
    spaces are not allowed around `=` signs, but are required between
    option clauses. If `=`value is omitted, the named option is changed
    in the same way as for `\pset` option with no explicit value.

    If a filename or `|`command argument is given, the query\'s output
    is written to the named file or piped to the given shell command,
    instead of displaying it as usual. The file or command is written to
    only if the query successfully returns zero or more tuples, not if
    the query fails or is a non-data-returning SQL command.

    If the current query buffer is empty, the most recently sent query
    is re-executed instead. Except for that behavior, `\g` without any
    arguments is essentially equivalent to a semicolon. With arguments,
    `\g` provides a "one-shot" alternative to the `\o` command, and
    additionally allows one-shot adjustments of the output formatting
    options normally set by `\pset`.

    When the last argument begins with `|`, the entire remainder of the
    line is taken to be the command to execute, and neither variable
    interpolation nor backquote expansion are performed in it. The rest
    of the line is simply passed literally to the shell.

`\gdesc`

:   Shows the description (that is, the column names and data types) of
    the result of the current query buffer. The query is not actually
    executed; however, if it contains some type of syntax error, that
    error will be reported in the normal way.

    If the current query buffer is empty, the most recently sent query
    is described instead.

`\getenv psql_var env_var`

:   Gets the value of the environment variable env\_var and assigns it
    to the psql variable psql\_var. If env\_var is not defined in the
    psql process\'s environment, psql\_var is not changed. Example:

        => \getenv home HOME
        => \echo :home
        /home/postgres

`\gexec`

:   Sends the current query buffer to the server, then treats each
    column of each row of the query\'s output (if any) as an SQL
    statement to be executed. For example, to create an index on each
    column of my\_table:

        => SELECT format('create index on my_table(%I)', attname)
        -> FROM pg_attribute
        -> WHERE attrelid = 'my_table'::regclass AND attnum > 0
        -> ORDER BY attnum
        -> \gexec
        CREATE INDEX
        CREATE INDEX
        CREATE INDEX
        CREATE INDEX

    The generated queries are executed in the order in which the rows
    are returned, and left-to-right within each row if there is more
    than one column. NULL fields are ignored. The generated queries are
    sent literally to the server for processing, so they cannot be psql
    meta-commands nor contain psql variable references. If any
    individual query fails, execution of the remaining queries continues
    unless `ON_ERROR_STOP` is set. Execution of each query is subject to
    `ECHO` processing. (Setting `ECHO` to `all` or `queries` is often
    advisable when using `\gexec`.) Query logging, single-step mode,
    timing, and other query execution features apply to each generated
    query as well.

    If the current query buffer is empty, the most recently sent query
    is re-executed instead.

`\gset [ prefix ]`

:   Sends the current query buffer to the server and stores the query\'s
    output into psql variables (see [Variables](#app-psql-variables)
    below). The query to be executed must return exactly one row. Each
    column of the row is stored into a separate variable, named the same
    as the column. For example:

        => SELECT 'hello' AS var1, 10 AS var2
        -> \gset
        => \echo :var1 :var2
        hello 10

    If you specify a prefix, that string is prepended to the query\'s
    column names to create the variable names to use:

        => SELECT 'hello' AS var1, 10 AS var2
        -> \gset result_
        => \echo :result_var1 :result_var2
        hello 10

    If a column result is NULL, the corresponding variable is unset
    rather than being set.

    If the query fails or does not return one row, no variables are
    changed.

    If the current query buffer is empty, the most recently sent query
    is re-executed instead.

`\gx [ (option=value [...]) ] [ filename ]`; `\gx [ (option=value [...]) ] [ |command ]`

:   `\gx` is equivalent to `\g`, except that it forces expanded output
    mode for this query, as if `expanded=on` were included in the list
    of `\pset` options. See also `\x`.

`\h` or `\help` `[ command ]`

:   Gives syntax help on the specified SQL command. If command is not
    specified, then psql will list all the commands for which syntax
    help is available. If command is an asterisk (`*`), then syntax help
    on all SQL commands is shown.

    Unlike most other meta-commands, the entire remainder of the line is
    always taken to be the argument(s) of `\help`, and neither variable
    interpolation nor backquote expansion are performed in the
    arguments.

    > **Note**
    >
    > To simplify typing, commands that consists of several words do not
    > have to be quoted. Thus it is fine to type `\help
    >         alter table`.

`\H` or `\html`

:   Turns on HTML query output format. If the HTML format is already on,
    it is switched back to the default aligned text format. This command
    is for compatibility and convenience, but see `\pset` about setting
    other output options.

`\i` or `\include` filename

:   Reads input from the file filename and executes it as though it had
    been typed on the keyboard.

    If filename is `-` (hyphen), then standard input is read until an
    EOF indication or `\q` meta-command. This can be used to intersperse
    interactive input with input from files. Note that Readline behavior
    will be used only if it is active at the outermost level.

    > **Note**
    >
    > If you want to see the lines on the screen as they are read you
    > must set the variable `ECHO` to `all`.

`\if` expression; `\elif` expression; `\else`; `\endif`

:   This group of commands implements nestable conditional blocks. A
    conditional block must begin with an `\if` and end with an `\endif`.
    In between there may be any number of `\elif` clauses, which may
    optionally be followed by a single `\else` clause. Ordinary queries
    and other types of backslash commands may (and usually do) appear
    between the commands forming a conditional block.

    The `\if` and `\elif` commands read their argument(s) and evaluate
    them as a Boolean expression. If the expression yields `true` then
    processing continues normally; otherwise, lines are skipped until a
    matching `\elif`, `\else`, or `\endif` is reached. Once an `\if` or
    `\elif` test has succeeded, the arguments of later `\elif` commands
    in the same block are not evaluated but are treated as false. Lines
    following an `\else` are processed only if no earlier matching `\if`
    or `\elif` succeeded.

    The expression argument of an `\if` or `\elif` command is subject to
    variable interpolation and backquote expansion, just like any other
    backslash command argument. After that it is evaluated like the
    value of an on/off option variable. So a valid value is any
    unambiguous case-insensitive match for one of: `true`, `false`, `1`,
    `0`, `on`, `off`, `yes`, `no`. For example, `t`, `T`, and `tR` will
    all be considered to be `true`.

    Expressions that do not properly evaluate to true or false will
    generate a warning and be treated as false.

    Lines being skipped are parsed normally to identify queries and
    backslash commands, but queries are not sent to the server, and
    backslash commands other than conditionals (`\if`, `\elif`, `\else`,
    `\endif`) are ignored. Conditional commands are checked only for
    valid nesting. Variable references in skipped lines are not
    expanded, and backquote expansion is not performed either.

    All the backslash commands of a given conditional block must appear
    in the same source file. If EOF is reached on the main input file or
    an `\include`-ed file before all local `\if`-blocks have been
    closed, then psql will raise an error.

    Here is an example:

        -- check for the existence of two separate records in the database and store
        -- the results in separate psql variables
        SELECT
            EXISTS(SELECT 1 FROM customer WHERE customer_id = 123) as is_customer,
            EXISTS(SELECT 1 FROM employee WHERE employee_id = 456) as is_employee
        \gset
        \if :is_customer
            SELECT * FROM customer WHERE customer_id = 123;
        \elif :is_employee
            \echo 'is not a customer but is an employee'
            SELECT * FROM employee WHERE employee_id = 456;
        \else
            \if yes
                \echo 'not a customer or employee'
            \else
                \echo 'this will never print'
            \endif
        \endif

`\ir` or `\include_relative` filename

:   The `\ir` command is similar to `\i`, but resolves relative file
    names differently. When executing in interactive mode, the two
    commands behave identically. However, when invoked from a script,
    `\ir` interprets file names relative to the directory in which the
    script is located, rather than the current working directory.

`\l[+]` or `\list[+] [ pattern ]`

:   List the databases in the server and show their names, owners,
    character set encodings, and access privileges. If pattern is
    specified, only databases whose names match the pattern are listed.
    If `+` is appended to the command name, database sizes, default
    tablespaces, and descriptions are also displayed. (Size information
    is only available for databases that the current user can connect
    to.)

`\lo_export loid filename`

:   Reads the large object with OID loid from the database and writes it
    to filename. Note that this is subtly different from the server
    function `lo_export`, which acts with the permissions of the user
    that the database server runs as and on the server\'s file system.

    > **Tip**
    >
    > Use `\lo_list` to find out the large object\'s OID.

`\lo_import filename [ comment ]`

:   Stores the file into a PostgreSQL large object. Optionally, it
    associates the given comment with the object. Example:

        foo=> \lo_import '/home/peter/pictures/photo.xcf' 'a picture of me'
        lo_import 152801

    The response indicates that the large object received object ID
    152801, which can be used to access the newly-created large object
    in the future. For the sake of readability, it is recommended to
    always associate a human-readable comment with every object. Both
    OIDs and comments can be viewed with the `\lo_list` command.

    Note that this command is subtly different from the server-side
    `lo_import` because it acts as the local user on the local file
    system, rather than the server\'s user and file system.

`\lo_list[+]`

:   Shows a list of all PostgreSQL large objects currently stored in the
    database, along with any comments provided for them. If `+` is
    appended to the command name, each large object is listed with its
    associated permissions, if any.

`\lo_unlink loid`

:   Deletes the large object with OID loid from the database.

    > **Tip**
    >
    > Use `\lo_list` to find out the large object\'s OID.

`\o` or `\out [ filename ]`; `\o` or `\out [ |command ]`

:   Arranges to save future query results to the file filename or pipe
    future results to the shell command command. If no argument is
    specified, the query output is reset to the standard output.

    If the argument begins with `|`, then the entire remainder of the
    line is taken to be the command to execute, and neither variable
    interpolation nor backquote expansion are performed in it. The rest
    of the line is simply passed literally to the shell.

    "Query results" includes all tables, command responses, and notices
    obtained from the database server, as well as output of various
    backslash commands that query the database (such as `\d`); but not
    error messages.

    > **Tip**
    >
    > To intersperse text output in between query results, use `\qecho`.

`\p` or `\print`

:   Print the current query buffer to the standard output. If the
    current query buffer is empty, the most recently executed query is
    printed instead.

`\password [ username ]`

:   Changes the password of the specified user (by default, the current
    user). This command prompts for the new password, encrypts it, and
    sends it to the server as an `ALTER ROLE` command. This makes sure
    that the new password does not appear in cleartext in the command
    history, the server log, or elsewhere.

`\prompt [ text ] name`

:   Prompts the user to supply text, which is assigned to the variable
    name. An optional prompt string, text, can be specified. (For
    multiword prompts, surround the text with single quotes.)

    By default, `\prompt` uses the terminal for input and output.
    However, if the `-f` command line switch was used, `\prompt` uses
    standard input and standard output.

`\pset [ option [ value ] ]`

:   This command sets options affecting the output of query result
    tables. option indicates which option is to be set. The semantics of
    value vary depending on the selected option. For some options,
    omitting value causes the option to be toggled or unset, as
    described under the particular option. If no such behavior is
    mentioned, then omitting value just results in the current setting
    being displayed.

    `\pset` without any arguments displays the current status of all
    printing options.

    Adjustable printing options are:

    `border`

    :   The value must be a number. In general, the higher the number
        the more borders and lines the tables will have, but details
        depend on the particular format. In HTML format, this will
        translate directly into the `border=...` attribute. In most
        other formats only values 0 (no border), 1 (internal dividing
        lines), and 2 (table frame) make sense, and values above 2 will
        be treated the same as `border = 2`. The `latex` and
        `latex-longtable` formats additionally allow a value of 3 to add
        dividing lines between data rows.

    `columns`

    :   Sets the target width for the `wrapped` format, and also the
        width limit for determining whether output is wide enough to
        require the pager or switch to the vertical display in expanded
        auto mode. Zero (the default) causes the target width to be
        controlled by the environment variable COLUMNS, or the detected
        screen width if COLUMNS is not set. In addition, if `columns` is
        zero then the `wrapped` format only affects screen output. If
        `columns` is nonzero then file and pipe output is wrapped to
        that width as well.

    `csv_fieldsep`

    :   Specifies the field separator to be used in CSV output format.
        If the separator character appears in a field\'s value, that
        field is output within double quotes, following standard CSV
        rules. The default is a comma.

    `expanded` (or `x`)

    :   If value is specified it must be either `on` or `off`, which
        will enable or disable expanded mode, or `auto`. If value is
        omitted the command toggles between the on and off settings.
        When expanded mode is enabled, query results are displayed in
        two columns, with the column name on the left and the data on
        the right. This mode is useful if the data wouldn\'t fit on the
        screen in the normal "horizontal" mode. In the auto setting, the
        expanded mode is used whenever the query output has more than
        one column and is wider than the screen; otherwise, the regular
        mode is used. The auto setting is only effective in the aligned
        and wrapped formats. In other formats, it always behaves as if
        the expanded mode is off.

    `fieldsep`

    :   Specifies the field separator to be used in unaligned output
        format. That way one can create, for example, tab-separated
        output, which other programs might prefer. To set a tab as field
        separator, type `\pset fieldsep
                  '\t'`. The default field separator is `'|'` (a
        vertical bar).

    `fieldsep_zero`

    :   Sets the field separator to use in unaligned output format to a
        zero byte.

    `footer`

    :   If value is specified it must be either `on` or `off` which will
        enable or disable display of the table footer (the `(n rows)`
        count). If value is omitted the command toggles footer display
        on or off.

    `format`

    :   Sets the output format to one of `aligned`, `asciidoc`, `csv`,
        `html`, `latex`, `latex-longtable`, `troff-ms`, `unaligned`, or
        `wrapped`. Unique abbreviations are allowed.

        `aligned` format is the standard, human-readable, nicely
        formatted text output; this is the default.

        `unaligned` format writes all columns of a row on one line,
        separated by the currently active field separator. This is
        useful for creating output that might be intended to be read in
        by other programs, for example, tab-separated or comma-separated
        format. However, the field separator character is not treated
        specially if it appears in a column\'s value; so CSV format may
        be better suited for such purposes.

        `csv` format CSV (Comma-Separated Values) format in psql writes
        column values separated by commas, applying the quoting rules
        described in [RFC 4180](https://tools.ietf.org/html/rfc4180).
        This output is compatible with the CSV format of the server\'s
        `COPY` command. A header line with column names is generated
        unless the `tuples_only` parameter is `on`. Titles and footers
        are not printed. Each row is terminated by the system-dependent
        end-of-line character, which is typically a single newline
        (`\n`) for Unix-like systems or a carriage return and newline
        sequence (`\r\n`) for Microsoft Windows. Field separator
        characters other than comma can be selected with
        `\pset csv_fieldsep`.

        `wrapped` format is like `aligned` but wraps wide data values
        across lines to make the output fit in the target column width.
        The target width is determined as described under the `columns`
        option. Note that psql will not attempt to wrap column header
        titles; therefore, `wrapped` format behaves the same as
        `aligned` if the total width needed for column headers exceeds
        the target.

        The `asciidoc`, `html`, `latex`, `latex-longtable`, and
        `troff-ms` formats put out tables that are intended to be
        included in documents using the respective mark-up language.
        They are not complete documents! This might not be necessary in
        HTML, but in LaTeX you must have a complete document wrapper.
        The `latex` format uses LaTeX\'s `tabular` environment. The
        `latex-longtable` format requires the LaTeX `longtable` and
        `booktabs` packages.

    `linestyle`

    :   Sets the border line drawing style to one of `ascii`,
        `old-ascii`, or `unicode`. Unique abbreviations are allowed.
        (That would mean one letter is enough.) The default setting is
        `ascii`. This option only affects the `aligned` and `wrapped`
        output formats.

        `ascii` style uses plain ASCII characters. Newlines in data are
        shown using a `+` symbol in the right-hand margin. When the
        `wrapped` format wraps data from one line to the next without a
        newline character, a dot (`.`) is shown in the right-hand margin
        of the first line, and again in the left-hand margin of the
        following line.

        `old-ascii` style uses plain ASCII characters, using the
        formatting style used in PostgreSQL 8.4 and earlier. Newlines in
        data are shown using a `:` symbol in place of the left-hand
        column separator. When the data is wrapped from one line to the
        next without a newline character, a `;` symbol is used in place
        of the left-hand column separator.

        `unicode` style uses Unicode box-drawing characters. Newlines in
        data are shown using a carriage return symbol in the right-hand
        margin. When the data is wrapped from one line to the next
        without a newline character, an ellipsis symbol is shown in the
        right-hand margin of the first line, and again in the left-hand
        margin of the following line.

        When the `border` setting is greater than zero, the `linestyle`
        option also determines the characters with which the border
        lines are drawn. Plain ASCII characters work everywhere, but
        Unicode characters look nicer on displays that recognize them.

    `null`

    :   Sets the string to be printed in place of a null value. The
        default is to print nothing, which can easily be mistaken for an
        empty string. For example, one might prefer `\pset null
                  '(null)'`.

    `numericlocale`

    :   If value is specified it must be either `on` or `off` which will
        enable or disable display of a locale-specific character to
        separate groups of digits to the left of the decimal marker. If
        value is omitted the command toggles between regular and
        locale-specific numeric output.

    `pager`

    :   Controls use of a pager program for query and psql help output.
        If the environment variable PSQL\_PAGER or PAGER is set, the
        output is piped to the specified program. Otherwise a
        platform-dependent default program (such as `more`) is used.

        When using the `\watch` command to execute a query repeatedly,
        the environment variable PSQL\_WATCH\_PAGER is used to find the
        pager program instead, on Unix systems. This is configured
        separately because it may confuse traditional pagers, but can be
        used to send output to tools that understand psql\'s output
        format (such as `pspg --stream`).

        When the `pager` option is `off`, the pager program is not used.
        When the `pager` option is `on`, the pager is used when
        appropriate, i.e., when the output is to a terminal and will not
        fit on the screen. The `pager` option can also be set to
        `always`, which causes the pager to be used for all terminal
        output regardless of whether it fits on the screen.
        `\pset pager` without a value toggles pager use on and off.

    `pager_min_lines`

    :   If `pager_min_lines` is set to a number greater than the page
        height, the pager program will not be called unless there are at
        least this many lines of output to show. The default setting
        is 0.

    `recordsep`

    :   Specifies the record (line) separator to use in unaligned output
        format. The default is a newline character.

    `recordsep_zero`

    :   Sets the record separator to use in unaligned output format to a
        zero byte.

    `tableattr` (or `T`)

    :   In HTML format, this specifies attributes to be placed inside
        the table tag. This could for example be `cellpadding` or
        `bgcolor`. Note that you probably don\'t want to specify
        `border` here, as that is already taken care of by
        `\pset border`. If no value is given, the table attributes are
        unset.

        In `latex-longtable` format, this controls the proportional
        width of each column containing a left-aligned data type. It is
        specified as a whitespace-separated list of values, e.g.,
        `'0.2 0.2 0.6'`. Unspecified output columns use the last
        specified value.

    `title` (or `C`)

    :   Sets the table title for any subsequently printed tables. This
        can be used to give your output descriptive tags. If no value is
        given, the title is unset.

    `tuples_only` (or `t`)

    :   If value is specified it must be either `on` or `off` which will
        enable or disable tuples-only mode. If value is omitted the
        command toggles between regular and tuples-only output. Regular
        output includes extra information such as column headers,
        titles, and various footers. In tuples-only mode, only actual
        table data is shown.

    `unicode_border_linestyle`

    :   Sets the border drawing style for the `unicode` line style to
        one of `single` or `double`.

    `unicode_column_linestyle`

    :   Sets the column drawing style for the `unicode` line style to
        one of `single` or `double`.

    `unicode_header_linestyle`

    :   Sets the header drawing style for the `unicode` line style to
        one of `single` or `double`.

    Illustrations of how these different formats look can be seen in
    [Examples](#app-psql-examples), below.

    > **Tip**
    >
    > There are various shortcut commands for `\pset`. See `\a`, `\C`,
    > `\f`, `\H`, `\t`, `\T`, and `\x`.

`\q` or `\quit`

:   Quits the psql program. In a script file, only execution of that
    script is terminated.

`\qecho text [ ... ] `

:   This command is identical to `\echo` except that the output will be
    written to the query output channel, as set by `\o`.

`\r` or `\reset`

:   Resets (clears) the query buffer.

`\s [ filename ]`

:   Print psql\'s command line history to filename. If filename is
    omitted, the history is written to the standard output (using the
    pager if appropriate). This command is not available if psql was
    built without Readline support.

`\set [ name [ value [ ... ] ] ]`

:   Sets the psql variable name to value, or if more than one value is
    given, to the concatenation of all of them. If only one argument is
    given, the variable is set to an empty-string value. To unset a
    variable, use the `\unset` command.

    `\set` without any arguments displays the names and values of all
    currently-set psql variables.

    Valid variable names can contain letters, digits, and underscores.
    See [Variables](#app-psql-variables) below for details. Variable
    names are case-sensitive.

    Certain variables are special, in that they control psql\'s behavior
    or are automatically set to reflect connection state. These
    variables are documented in [Variables](#app-psql-variables), below.

    > **Note**
    >
    > This command is unrelated to the SQL command [`SET`](#sql-set).

`\setenv name [ value ]`

:   Sets the environment variable name to value, or if the value is not
    supplied, unsets the environment variable. Example:

        testdb=> \setenv PAGER less
        testdb=> \setenv LESS -imx4F

`\sf[+] function_description `

:   This command fetches and shows the definition of the named function
    or procedure, in the form of a `CREATE OR REPLACE FUNCTION` or
    `CREATE OR REPLACE PROCEDURE` command. The definition is printed to
    the current query output channel, as set by `\o`.

    The target function can be specified by name alone, or by name and
    arguments, for example `foo(integer, text)`. The argument types must
    be given if there is more than one function of the same name.

    If `+` is appended to the command name, then the output lines are
    numbered, with the first line of the function body being line 1.

    Unlike most other meta-commands, the entire remainder of the line is
    always taken to be the argument(s) of `\sf`, and neither variable
    interpolation nor backquote expansion are performed in the
    arguments.

`\sv[+] view_name `

:   This command fetches and shows the definition of the named view, in
    the form of a `CREATE OR REPLACE VIEW` command. The definition is
    printed to the current query output channel, as set by `\o`.

    If `+` is appended to the command name, then the output lines are
    numbered from 1.

    Unlike most other meta-commands, the entire remainder of the line is
    always taken to be the argument(s) of `\sv`, and neither variable
    interpolation nor backquote expansion are performed in the
    arguments.

`\t`

:   Toggles the display of output column name headings and row count
    footer. This command is equivalent to `\pset
            tuples_only` and is provided for convenience.

`\T table_options`

:   Specifies attributes to be placed within the table tag in HTML
    output format. This command is equivalent to `\pset
            tableattr table_options`.

`\timing [ on | off ]`

:   With a parameter, turns displaying of how long each SQL statement
    takes on or off. Without a parameter, toggles the display between on
    and off. The display is in milliseconds; intervals longer than 1
    second are also shown in minutes:seconds format, with hours and days
    fields added if needed.

`\unset name`

:   Unsets (deletes) the psql variable name.

    Most variables that control psql\'s behavior cannot be unset;
    instead, an `\unset` command is interpreted as setting them to their
    default values. See [Variables](#app-psql-variables) below.

`\w` or `\write` filename; `\w` or `\write` `|`command

:   Writes the current query buffer to the file filename or pipes it to
    the shell command command. If the current query buffer is empty, the
    most recently executed query is written instead.

    If the argument begins with `|`, then the entire remainder of the
    line is taken to be the command to execute, and neither variable
    interpolation nor backquote expansion are performed in it. The rest
    of the line is simply passed literally to the shell.

`\warn text [ ... ]`

:   This command is identical to `\echo` except that the output will be
    written to psql\'s standard error channel, rather than standard
    output.

`\watch [ seconds ]`

:   Repeatedly execute the current query buffer (as `\g` does) until
    interrupted or the query fails. Wait the specified number of seconds
    (default 2) between executions. Each query result is displayed with
    a header that includes the `\pset title` string (if any), the time
    as of query start, and the delay interval.

    If the current query buffer is empty, the most recently sent query
    is re-executed instead.

`\x [ on | off | auto ]`

:   Sets or toggles expanded table formatting mode. As such it is
    equivalent to `\pset expanded`.

`\z [ pattern ]`

:   Lists tables, views and sequences with their associated access
    privileges. If a pattern is specified, only tables, views and
    sequences whose names match the pattern are listed.

    This is an alias for `\dp` ("display privileges").

`\! [ command ]`

:   With no argument, escapes to a sub-shell; psql resumes when the
    sub-shell exits. With an argument, executes the shell command
    command.

    Unlike most other meta-commands, the entire remainder of the line is
    always taken to be the argument(s) of `\!`, and neither variable
    interpolation nor backquote expansion are performed in the
    arguments. The rest of the line is simply passed literally to the
    shell.

`\? [ topic ]`

:   Shows help information. The optional topic parameter (defaulting to
    `commands`) selects which part of psql is explained: `commands`
    describes psql\'s backslash commands; `options` describes the
    command-line options that can be passed to psql; and `variables`
    shows help about psql configuration variables.

`\;`

:   Backslash-semicolon is not a meta-command in the same way as the
    preceding commands; rather, it simply causes a semicolon to be added
    to the query buffer without any further processing.

    Normally, psql will dispatch an SQL command to the server as soon as
    it reaches the command-ending semicolon, even if more input remains
    on the current line. Thus for example entering

        select 1; select 2; select 3;

    will result in the three SQL commands being individually sent to the
    server, with each one\'s results being displayed before continuing
    to the next command. However, a semicolon entered as `\;` will not
    trigger command processing, so that the command before it and the
    one after are effectively combined and sent to the server in one
    request. So for example

        select 1\; select 2\; select 3;

    results in sending the three SQL commands to the server in a single
    request, when the non-backslashed semicolon is reached. The server
    executes such a request as a single transaction, unless there are
    explicit `BEGIN`/`COMMIT` commands included in the string to divide
    it into multiple transactions. (See
    [???](#protocol-flow-multi-statement) for more details about how the
    server handles multi-query strings.)

### Patterns {#app-psql-patterns}

patterns

in psql and pg\_dump

The various `\d` commands accept a pattern parameter to specify the
object name(s) to be displayed. In the simplest case, a pattern is just
the exact name of the object. The characters within a pattern are
normally folded to lower case, just as in SQL names; for example,
`\dt FOO` will display the table named `foo`. As in SQL names, placing
double quotes around a pattern stops folding to lower case. Should you
need to include an actual double quote character in a pattern, write it
as a pair of double quotes within a double-quote sequence; again this is
in accord with the rules for SQL quoted identifiers. For example,
`\dt "FOO""BAR"` will display the table named `FOO"BAR` (not `foo"bar`).
Unlike the normal rules for SQL names, you can put double quotes around
just part of a pattern, for instance `\dt FOO"FOO"BAR` will display the
table named `fooFOObar`.

Whenever the pattern parameter is omitted completely, the `\d` commands
display all objects that are visible in the current schema search path
MDASH this is equivalent to using `*` as the pattern. (An object is said
to be visible if its containing schema is in the search path and no
object of the same kind and name appears earlier in the search path.
This is equivalent to the statement that the object can be referenced by
name without explicit schema qualification.) To see all objects in the
database regardless of visibility, use `*.*` as the pattern.

Within a pattern, `*` matches any sequence of characters (including no
characters) and `?` matches any single character. (This notation is
comparable to Unix shell file name patterns.) For example, `\dt int*`
displays tables whose names begin with `int`. But within double quotes,
`*` and `?` lose these special meanings and are just matched literally.

A pattern that contains a dot (`.`) is interpreted as a schema name
pattern followed by an object name pattern. For example,
`\dt foo*.*bar*` displays all tables whose table name includes `bar`
that are in schemas whose schema name starts with `foo`. When no dot
appears, then the pattern matches only objects that are visible in the
current schema search path. Again, a dot within double quotes loses its
special meaning and is matched literally.

Advanced users can use regular-expression notations such as character
classes, for example `[0-9]` to match any digit. All regular expression
special characters work as specified in [???](#functions-posix-regexp),
except for `.` which is taken as a separator as mentioned above, `*`
which is translated to the regular-expression notation `.*`, `?` which
is translated to `.`, and `$` which is matched literally. You can
emulate these pattern characters at need by writing `?` for `.`, `(R+|)`
for `R*`, or `(R|)` for `R?`. `$` is not needed as a regular-expression
character since the pattern must match the whole name, unlike the usual
interpretation of regular expressions (in other words, `$` is
automatically appended to your pattern). Write `*` at the beginning
and/or end if you don\'t wish the pattern to be anchored. Note that
within double quotes, all regular expression special characters lose
their special meanings and are matched literally. Also, the regular
expression special characters are matched literally in operator name
patterns (i.e., the argument of `\do`).

Advanced Features
-----------------

### Variables {#app-psql-variables}

psql provides variable substitution features similar to common Unix
command shells. Variables are simply name/value pairs, where the value
can be any string of any length. The name must consist of letters
(including non-Latin letters), digits, and underscores.

To set a variable, use the psql meta-command `\set`. For example,

    testdb=> \set foo bar

sets the variable `foo` to the value `bar`. To retrieve the content of
the variable, precede the name with a colon, for example:

    testdb=> \echo :foo
    bar

This works in both regular SQL commands and meta-commands; there is more
detail in [SQL Interpolation](#app-psql-interpolation), below.

If you call `\set` without a second argument, the variable is set to an
empty-string value. To unset (i.e., delete) a variable, use the command
`\unset`. To show the values of all variables, call `\set` without any
argument.

> **Note**
>
> The arguments of `\set` are subject to the same substitution rules as
> with other commands. Thus you can construct interesting references
> such as `\set :foo
>     'something'` and get "soft links" or "variable variables" of Perl
> or PHP fame, respectively. Unfortunately (or fortunately?), there is
> no way to do anything useful with these constructs. On the other hand,
> `\set bar :foo` is a perfectly valid way to copy a variable.

A number of these variables are treated specially by psql. They
represent certain option settings that can be changed at run time by
altering the value of the variable, or in some cases represent
changeable state of psql. By convention, all specially treated
variables\' names consist of all upper-case ASCII letters (and possibly
digits and underscores). To ensure maximum compatibility in the future,
avoid using such variable names for your own purposes.

Variables that control psql\'s behavior generally cannot be unset or set
to invalid values. An `\unset` command is allowed but is interpreted as
setting the variable to its default value. A `\set` command without a
second argument is interpreted as setting the variable to `on`, for
control variables that accept that value, and is rejected for others.
Also, control variables that accept the values `on` and `off` will also
accept other common spellings of Boolean values, such as `true` and
`false`.

The specially treated variables are:

`AUTOCOMMIT` autocommit psql

:   When `on` (the default), each SQL command is automatically committed
    upon successful completion. To postpone commit in this mode, you
    must enter a `BEGIN` or `START
            TRANSACTION` SQL command. When `off` or unset, SQL commands
    are not committed until you explicitly issue `COMMIT` or `END`. The
    autocommit-off mode works by issuing an implicit `BEGIN` for you,
    just before any command that is not already in a transaction block
    and is not itself a `BEGIN` or other transaction-control command,
    nor a command that cannot be executed inside a transaction block
    (such as `VACUUM`).

    > **Note**
    >
    > In autocommit-off mode, you must explicitly abandon any failed
    > transaction by entering `ABORT` or `ROLLBACK`. Also keep in mind
    > that if you exit the session without committing, your work will be
    > lost.

    > **Note**
    >
    > The autocommit-on mode is PostgreSQL\'s traditional behavior, but
    > autocommit-off is closer to the SQL spec. If you prefer
    > autocommit-off, you might wish to set it in the system-wide
    > `psqlrc` file or your `~/.psqlrc` file.

`COMP_KEYWORD_CASE`

:   Determines which letter case to use when completing an SQL key word.
    If set to `lower` or `upper`, the completed word will be in lower or
    upper case, respectively. If set to `preserve-lower` or
    `preserve-upper` (the default), the completed word will be in the
    case of the word already entered, but words being completed without
    anything entered will be in lower or upper case, respectively.

`DBNAME`

:   The name of the database you are currently connected to. This is set
    every time you connect to a database (including program start-up),
    but can be changed or unset.

`ECHO`

:   If set to `all`, all nonempty input lines are printed to standard
    output as they are read. (This does not apply to lines read
    interactively.) To select this behavior on program start-up, use the
    switch `-a`. If set to `queries`, psql prints each query to standard
    output as it is sent to the server. The switch to select this
    behavior is `-e`. If set to `errors`, then only failed queries are
    displayed on standard error output. The switch for this behavior is
    `-b`. If set to `none` (the default), then no queries are displayed.

`ECHO_HIDDEN`

:   When this variable is set to `on` and a backslash command queries
    the database, the query is first shown. This feature helps you to
    study PostgreSQL internals and provide similar functionality in your
    own programs. (To select this behavior on program start-up, use the
    switch `-E`.) If you set this variable to the value `noexec`, the
    queries are just shown but are not actually sent to the server and
    executed. The default value is `off`.

`ENCODING`

:   The current client character set encoding. This is set every time
    you connect to a database (including program start-up), and when you
    change the encoding with `\encoding`, but it can be changed or
    unset.

`ERROR`

:   `true` if the last SQL query failed, `false` if it succeeded. See
    also `SQLSTATE`.

`FETCH_COUNT`

:   If this variable is set to an integer value greater than zero, the
    results of `SELECT` queries are fetched and displayed in groups of
    that many rows, rather than the default behavior of collecting the
    entire result set before display. Therefore only a limited amount of
    memory is used, regardless of the size of the result set. Settings
    of 100 to 1000 are commonly used when enabling this feature. Keep in
    mind that when using this feature, a query might fail after having
    already displayed some rows.

    > **Tip**
    >
    > Although you can use any output format with this feature, the
    > default `aligned` format tends to look bad because each group of
    > `FETCH_COUNT` rows will be formatted separately, leading to
    > varying column widths across the row groups. The other output
    > formats work better.

`HIDE_TABLEAM`

:   If this variable is set to `true`, a table\'s access method details
    are not displayed. This is mainly useful for regression tests.

`HIDE_TOAST_COMPRESSION`

:   If this variable is set to `true`, column compression method details
    are not displayed. This is mainly useful for regression tests.

`HISTCONTROL`

:   If this variable is set to `ignorespace`, lines which begin with a
    space are not entered into the history list. If set to a value of
    `ignoredups`, lines matching the previous history line are not
    entered. A value of `ignoreboth` combines the two options. If set to
    `none` (the default), all lines read in interactive mode are saved
    on the history list.

    > **Note**
    >
    > This feature was shamelessly plagiarized from Bash.

`HISTFILE`

:   The file name that will be used to store the history list. If unset,
    the file name is taken from the PSQL\_HISTORY environment variable.
    If that is not set either, the default is `~/.psql_history`, or
    `%APPDATA%\postgresql\psql_history` on Windows. For example,
    putting:

        \set HISTFILE ~/.psql_history-:DBNAME

    in `~/.psqlrc` will cause psql to maintain a separate history for
    each database.

    > **Note**
    >
    > This feature was shamelessly plagiarized from Bash.

`HISTSIZE`

:   The maximum number of commands to store in the command history
    (default 500). If set to a negative value, no limit is applied.

    > **Note**
    >
    > This feature was shamelessly plagiarized from Bash.

`HOST`

:   The database server host you are currently connected to. This is set
    every time you connect to a database (including program start-up),
    but can be changed or unset.

`IGNOREEOF`

:   If set to 1 or less, sending an EOF character (usually
    [Control+D]{.keycombo}) to an interactive session of psql will
    terminate the application. If set to a larger numeric value, that
    many consecutive EOF characters must be typed to make an interactive
    session terminate. If the variable is set to a non-numeric value, it
    is interpreted as 10. The default is 0.

    > **Note**
    >
    > This feature was shamelessly plagiarized from Bash.

`LASTOID`

:   The value of the last affected OID, as returned from an `INSERT` or
    `\lo_import` command. This variable is only guaranteed to be valid
    until after the result of the next SQL command has been displayed.
    PostgreSQL servers since version 12 do not support OID system
    columns anymore, thus LASTOID will always be 0 following `INSERT`
    when targeting such servers.

`LAST_ERROR_MESSAGE`; `LAST_ERROR_SQLSTATE`

:   The primary error message and associated SQLSTATE code for the most
    recent failed query in the current psql session, or an empty string
    and `00000` if no error has occurred in the current session.

`ON_ERROR_ROLLBACK` rollback psql

:   When set to `on`, if a statement in a transaction block generates an
    error, the error is ignored and the transaction continues. When set
    to `interactive`, such errors are only ignored in interactive
    sessions, and not when reading script files. When set to `off` (the
    default), a statement in a transaction block that generates an error
    aborts the entire transaction. The error rollback mode works by
    issuing an implicit `SAVEPOINT` for you, just before each command
    that is in a transaction block, and then rolling back to the
    savepoint if the command fails.

`ON_ERROR_STOP`

:   By default, command processing continues after an error. When this
    variable is set to `on`, processing will instead stop immediately.
    In interactive mode, psql will return to the command prompt;
    otherwise, psql will exit, returning error code 3 to distinguish
    this case from fatal error conditions, which are reported using
    error code 1. In either case, any currently running scripts (the
    top-level script, if any, and any other scripts which it may have in
    invoked) will be terminated immediately. If the top-level command
    string contained multiple SQL commands, processing will stop with
    the current command.

`PORT`

:   The database server port to which you are currently connected. This
    is set every time you connect to a database (including program
    start-up), but can be changed or unset.

`PROMPT1`; `PROMPT2`; `PROMPT3`

:   These specify what the prompts psql issues should look like. See
    [Prompting](#app-psql-prompting) below.

`QUIET`

:   Setting this variable to `on` is equivalent to the command line
    option `-q`. It is probably not too useful in interactive mode.

`ROW_COUNT`

:   The number of rows returned or affected by the last SQL query, or 0
    if the query failed or did not report a row count.

`SERVER_VERSION_NAME`; `SERVER_VERSION_NUM`

:   The server\'s version number as a string, for example `9.6.2`,
    `10.1` or `11beta1`, and in numeric form, for example `90602` or
    `100001`. These are set every time you connect to a database
    (including program start-up), but can be changed or unset.

`SHOW_ALL_RESULTS`

:   When this variable is set to `off`, only the last result of a
    combined query (`\;`) is shown instead of all of them. The default
    is `on`. The off behavior is for compatibility with older versions
    of psql.

`SHOW_CONTEXT`

:   This variable can be set to the values `never`, `errors`, or
    `always` to control whether `CONTEXT` fields are displayed in
    messages from the server. The default is `errors` (meaning that
    context will be shown in error messages, but not in notice or
    warning messages). This setting has no effect when `VERBOSITY` is
    set to `terse` or `sqlstate`. (See also `\errverbose`, for use when
    you want a verbose version of the error you just got.)

`SINGLELINE`

:   Setting this variable to `on` is equivalent to the command line
    option `-S`.

`SINGLESTEP`

:   Setting this variable to `on` is equivalent to the command line
    option `-s`.

`SQLSTATE`

:   The error code (see [???](#errcodes-appendix)) associated with the
    last SQL query\'s failure, or `00000` if it succeeded.

`USER`

:   The database user you are currently connected as. This is set every
    time you connect to a database (including program start-up), but can
    be changed or unset.

`VERBOSITY`

:   This variable can be set to the values `default`, `verbose`,
    `terse`, or `sqlstate` to control the verbosity of error reports.
    (See also `\errverbose`, for use when you want a verbose version of
    the error you just got.)

`VERSION`; `VERSION_NAME`; `VERSION_NUM`

:   These variables are set at program start-up to reflect psql\'s
    version, respectively as a verbose string, a short string (e.g.,
    `9.6.2`, `10.1`, or `11beta1`), and a number (e.g., `90602` or
    `100001`). They can be changed or unset.

### SQL Interpolation {#app-psql-interpolation}

A key feature of psql variables is that you can substitute
("interpolate") them into regular SQL statements, as well as the
arguments of meta-commands. Furthermore, psql provides facilities for
ensuring that variable values used as SQL literals and identifiers are
properly quoted. The syntax for interpolating a value without any
quoting is to prepend the variable name with a colon (`:`). For example,

    testdb=> \set foo 'my_table'
    testdb=> SELECT * FROM :foo;

would query the table `my_table`. Note that this may be unsafe: the
value of the variable is copied literally, so it can contain unbalanced
quotes, or even backslash commands. You must make sure that it makes
sense where you put it.

When a value is to be used as an SQL literal or identifier, it is safest
to arrange for it to be quoted. To quote the value of a variable as an
SQL literal, write a colon followed by the variable name in single
quotes. To quote the value as an SQL identifier, write a colon followed
by the variable name in double quotes. These constructs deal correctly
with quotes and other special characters embedded within the variable
value. The previous example would be more safely written this way:

    testdb=> \set foo 'my_table'
    testdb=> SELECT * FROM :"foo";

Variable interpolation will not be performed within quoted SQL literals
and identifiers. Therefore, a construction such as `':foo'` doesn\'t
work to produce a quoted literal from a variable\'s value (and it would
be unsafe if it did work, since it wouldn\'t correctly handle quotes
embedded in the value).

One example use of this mechanism is to copy the contents of a file into
a table column. First load the file into a variable and then interpolate
the variable\'s value as a quoted string:

    testdb=> \set content `cat my_file.txt`
    testdb=> INSERT INTO my_table VALUES (:'content');

(Note that this still won\'t work if `my_file.txt` contains NUL bytes.
psql does not support embedded NUL bytes in variable values.)

Since colons can legally appear in SQL commands, an apparent attempt at
interpolation (that is, `:name`, `:'name'`, or `:"name"`) is not
replaced unless the named variable is currently set. In any case, you
can escape a colon with a backslash to protect it from substitution.

The `:{?name}` special syntax returns TRUE or FALSE depending on whether
the variable exists or not, and is thus always substituted, unless the
colon is backslash-escaped.

The colon syntax for variables is standard SQL for embedded query
languages, such as ECPG. The colon syntaxes for array slices and type
casts are PostgreSQL extensions, which can sometimes conflict with the
standard usage. The colon-quote syntax for escaping a variable\'s value
as an SQL literal or identifier is a psql extension.

### Prompting {#app-psql-prompting}

The prompts psql issues can be customized to your preference. The three
variables `PROMPT1`, `PROMPT2`, and `PROMPT3` contain strings and
special escape sequences that describe the appearance of the prompt.
Prompt 1 is the normal prompt that is issued when psql requests a new
command. Prompt 2 is issued when more input is expected during command
entry, for example because the command was not terminated with a
semicolon or a quote was not closed. Prompt 3 is issued when you are
running an SQL `COPY FROM STDIN` command and you need to type in a row
value on the terminal.

The value of the selected prompt variable is printed literally, except
where a percent sign (`%`) is encountered. Depending on the next
character, certain other text is substituted instead. Defined
substitutions are:

`%M`

:   The full host name (with domain name) of the database server, or
    `[local]` if the connection is over a Unix domain socket, or
    `[local:/dir/name]`, if the Unix domain socket is not at the
    compiled in default location.

`%m`

:   The host name of the database server, truncated at the first dot, or
    `[local]` if the connection is over a Unix domain socket.

`%>`

:   The port number at which the database server is listening.

`%n`

:   The database session user name. (The expansion of this value might
    change during a database session as the result of the command
    `SET SESSION
              AUTHORIZATION`.)

`%/`

:   The name of the current database.

`%~`

:   Like `%/`, but the output is `~` (tilde) if the database is your
    default database.

`%#`

:   If the session user is a database superuser, then a `#`, otherwise a
    `>`. (The expansion of this value might change during a database
    session as the result of the command `SET SESSION
              AUTHORIZATION`.)

`%p`

:   The process ID of the backend currently connected to.

`%R`

:   In prompt 1 normally `=`, but `@` if the session is in an inactive
    branch of a conditional block, or `^` if in single-line mode, or `!`
    if the session is disconnected from the database (which can happen
    if `\connect` fails). In prompt 2 `%R` is replaced by a character
    that depends on why psql expects more input: `-` if the command
    simply wasn\'t terminated yet, but `*` if there is an unfinished
    `/* ... */` comment, a single quote if there is an unfinished quoted
    string, a double quote if there is an unfinished quoted identifier,
    a dollar sign if there is an unfinished dollar-quoted string, or `(`
    if there is an unmatched left parenthesis. In prompt 3 `%R` doesn\'t
    produce anything.

`%x`

:   Transaction status: an empty string when not in a transaction block,
    or `*` when in a transaction block, or `!` when in a failed
    transaction block, or `?` when the transaction state is
    indeterminate (for example, because there is no connection).

`%l`

:   The line number inside the current statement, starting from `1`.

`%`digits

:   The character with the indicated octal code is substituted.

`%:`name`:`

:   The value of the psql variable name. See
    [Variables](#app-psql-variables), above, for details.

`` %` ``command`` ` ``

:   The output of command, similar to ordinary "back-tick" substitution.

`%[` \... `%]`

:   Prompts can contain terminal control characters which, for example,
    change the color, background, or style of the prompt text, or change
    the title of the terminal window. In order for the line editing
    features of Readline to work properly, these non-printing control
    characters must be designated as invisible by surrounding them with
    `%[` and `%]`. Multiple pairs of these can occur within the prompt.
    For example:

        testdb=> \set PROMPT1 '%[%033[1;33;40m%]%n@%/%R%[%033[0m%]%# '

    results in a boldfaced (`1;`) yellow-on-black (`33;40`) prompt on
    VT100-compatible, color-capable terminals.

`%w`

:   Whitespace of the same width as the most recent output of `PROMPT1`.
    This can be used as a `PROMPT2` setting, so that multi-line
    statements are aligned with the first line, but there is no visible
    secondary prompt.

To insert a percent sign into your prompt, write `%%`. The default
prompts are `'%/%R%x%# '` for prompts 1 and 2, and `'>> '` for prompt 3.

> **Note**
>
> This feature was shamelessly plagiarized from tcsh.

### Command-Line Editing {#app-psql-readline}

Readline

in psql

libedit

in psql

psql uses the Readline or libedit library, if available, for convenient
line editing and retrieval. The command history is automatically saved
when psql exits and is reloaded when psql starts up. Type up-arrow or
control-P to retrieve previous lines.

You can also use tab completion to fill in partially-typed keywords and
SQL object names in many (by no means all) contexts. For example, at the
start of a command, typing `ins` and pressing TAB will fill in
`insert into `. Then, typing a few characters of a table or schema name
and pressing TAB will fill in the unfinished name, or offer a menu of
possible completions when there\'s more than one. (Depending on the
library in use, you may need to press TAB more than once to get a menu.)

Tab completion for SQL object names requires sending queries to the
server to find possible matches. In some contexts this can interfere
with other operations. For example, after `BEGIN` it will be too late to
issue `SET TRANSACTION ISOLATION
    LEVEL` if a tab-completion query is issued in between. If you do not
want tab completion at all, you can turn it off permanently by putting
this in a file named `.inputrc` in your home directory:

    $if psql
    set disable-completion on
    $endif

(This is not a psql but a Readline feature. Read its documentation for
further details.)

The `-n` (`--no-readline`) command line option can also be useful to
disable use of Readline for a single run of psql. This prevents tab
completion, use or recording of command line history, and editing of
multi-line commands. It is particularly useful when you need to
copy-and-paste text that contains TAB characters.

Environment {#app-psql-environment}
===========

COLUMNS

:   If `\pset columns` is zero, controls the width for the `wrapped`
    format and width for determining if wide output requires the pager
    or should be switched to the vertical format in expanded auto mode.

PGDATABASE; PGHOST; PGPORT; PGUSER

:   Default connection parameters (see [???](#libpq-envars)).

PG\_COLOR

:   Specifies whether to use color in diagnostic messages. Possible
    values are `always`, `auto` and `never`.

PSQL\_EDITOR; EDITOR; VISUAL

:   Editor used by the `\e`, `\ef`, and `\ev` commands. These variables
    are examined in the order listed; the first that is set is used. If
    none of them is set, the default is to use `vi` on Unix systems or
    `notepad.exe` on Windows systems.

PSQL\_EDITOR\_LINENUMBER\_ARG

:   When `\e`, `\ef`, or `\ev` is used with a line number argument, this
    variable specifies the command-line argument used to pass the
    starting line number to the user\'s editor. For editors such as
    Emacs or vi, this is a plus sign. Include a trailing space in the
    value of the variable if there needs to be space between the option
    name and the line number. Examples:

        PSQL_EDITOR_LINENUMBER_ARG='+'
        PSQL_EDITOR_LINENUMBER_ARG='--line '

    The default is `+` on Unix systems (corresponding to the default
    editor `vi`, and useful for many other common editors); but there is
    no default on Windows systems.

PSQL\_HISTORY

:   Alternative location for the command history file. Tilde (`~`)
    expansion is performed.

PSQL\_PAGER; PAGER

:   If a query\'s results do not fit on the screen, they are piped
    through this command. Typical values are `more` or `less`. Use of
    the pager can be disabled by setting PSQL\_PAGER or PAGER to an
    empty string, or by adjusting the pager-related options of the
    `\pset` command. These variables are examined in the order listed;
    the first that is set is used. If none of them is set, the default
    is to use `more` on most platforms, but `less` on Cygwin.

PSQL\_WATCH\_PAGER

:   When a query is executed repeatedly with the `\watch` command, a
    pager is not used by default. This behavior can be changed by
    setting PSQL\_WATCH\_PAGER to a pager command, on Unix systems. The
    `pspg` pager (not part of PostgreSQL but available in many open
    source software distributions) can display the output of `\watch` if
    started with the option `--stream`.

PSQLRC

:   Alternative location of the user\'s `.psqlrc` file. Tilde (`~`)
    expansion is performed.

SHELL

:   Command executed by the `\!` command.

TMPDIR

:   Directory for storing temporary files. The default is `/tmp`.

This utility, like most other PostgreSQL utilities, also uses the
environment variables supported by libpq (see [???](#libpq-envars)).

Files
=====

`psqlrc` and `~/.psqlrc`

:   Unless it is passed an `-X` option, psql attempts to read and
    execute commands from the system-wide startup file (`psqlrc`) and
    then the user\'s personal startup file (`~/.psqlrc`), after
    connecting to the database but before accepting normal commands.
    These files can be used to set up the client and/or the server to
    taste, typically with `\set` and `SET` commands.

    The system-wide startup file is named `psqlrc` and is sought in the
    installation\'s "system configuration" directory, which is most
    reliably identified by running `pg_config
         --sysconfdir`. By default this directory will be `../etc/`
    relative to the directory containing the PostgreSQL executables. The
    name of this directory can be set explicitly via the PGSYSCONFDIR
    environment variable.

    The user\'s personal startup file is named `.psqlrc` and is sought
    in the invoking user\'s home directory. On Windows, which lacks such
    a concept, the personal startup file is named
    `%APPDATA%\postgresql\psqlrc.conf`. The location of the user\'s
    startup file can be set explicitly via the PSQLRC environment
    variable.

    Both the system-wide startup file and the user\'s personal startup
    file can be made psql-version-specific by appending a dash and the
    PostgreSQL major or minor release number to the file name, for
    example `~/.psqlrc-9.2` or `~/.psqlrc-9.2.5`. The most specific
    version-matching file will be read in preference to a
    non-version-specific file.

`.psql_history`

:   The command-line history is stored in the file `~/.psql_history`, or
    `%APPDATA%\postgresql\psql_history` on Windows.

    The location of the history file can be set explicitly via the
    `HISTFILE` psql variable or the PSQL\_HISTORY environment variable.

Notes
=====

-   psql works best with servers of the same or an older major version.
    Backslash commands are particularly likely to fail if the server is
    of a newer version than psql itself. However, backslash commands of
    the `\d` family should work with servers of versions back to 7.4,
    though not necessarily with servers newer than psql itself. The
    general functionality of running SQL commands and displaying query
    results should also work with servers of a newer major version, but
    this cannot be guaranteed in all cases.

    If you want to use psql to connect to several servers of different
    major versions, it is recommended that you use the newest version of
    psql. Alternatively, you can keep around a copy of psql from each
    major version and be sure to use the version that matches the
    respective server. But in practice, this additional complication
    should not be necessary.

-   Before PostgreSQL 9.6, the `-c` option implied `-X` (`--no-psqlrc`);
    this is no longer the case.

-   Before PostgreSQL 8.4, psql allowed the first argument of a
    single-letter backslash command to start directly after the command,
    without intervening whitespace. Now, some whitespace is required.

Notes for Windows Users
=======================

psql is built as a "console application". Since the Windows console
windows use a different encoding than the rest of the system, you must
take special care when using 8-bit characters within psql. If psql
detects a problematic console code page, it will warn you at startup. To
change the console code page, two things are necessary:

-   Set the code page by entering `cmd.exe /c chcp
          1252`. (1252 is a code page that is appropriate for German;
    replace it with your value.) If you are using Cygwin, you can put
    this command in `/etc/profile`.

-   Set the console font to `Lucida Console`, because the raster font
    does not work with the ANSI code page.

Examples {#app-psql-examples}
========

The first example shows how to spread a command over several lines of
input. Notice the changing prompt:

    testdb=> CREATE TABLE my_table (
    testdb(>  first integer not null default 0,
    testdb(>  second text)
    testdb-> ;
    CREATE TABLE

Now look at the table definition again:

    testdb=> \d my_table
                  Table "public.my_table"
     Column |  Type   | Collation | Nullable | Default
    --------+---------+-----------+----------+---------
     first  | integer |           | not null | 0
     second | text    |           |          | 

Now we change the prompt to something more interesting:

    testdb=> \set PROMPT1 '%n@%m %~%R%# '
    peter@localhost testdb=>

Let\'s assume you have filled the table with data and want to take a
look at it:

    peter@localhost testdb=> SELECT * FROM my_table;
     first | second
    -------+--------
         1 | one
         2 | two
         3 | three
         4 | four
    (4 rows)

You can display tables in different ways by using the `\pset` command:

    peter@localhost testdb=> \pset border 2
    Border style is 2.
    peter@localhost testdb=> SELECT * FROM my_table;
    +-------+--------+
    | first | second |
    +-------+--------+
    |     1 | one    |
    |     2 | two    |
    |     3 | three  |
    |     4 | four   |
    +-------+--------+
    (4 rows)

    peter@localhost testdb=> \pset border 0
    Border style is 0.
    peter@localhost testdb=> SELECT * FROM my_table;
    first second
    ----- ------
        1 one
        2 two
        3 three
        4 four
    (4 rows)

    peter@localhost testdb=> \pset border 1
    Border style is 1.
    peter@localhost testdb=> \pset format csv
    Output format is csv.
    peter@localhost testdb=> \pset tuples_only
    Tuples only is on.
    peter@localhost testdb=> SELECT second, first FROM my_table;
    one,1
    two,2
    three,3
    four,4
    peter@localhost testdb=> \pset format unaligned
    Output format is unaligned.
    peter@localhost testdb=> \pset fieldsep '\t'
    Field separator is "    ".
    peter@localhost testdb=> SELECT second, first FROM my_table;
    one     1
    two     2
    three   3
    four    4

Alternatively, use the short commands:

    peter@localhost testdb=> \a \t \x
    Output format is aligned.
    Tuples only is off.
    Expanded display is on.
    peter@localhost testdb=> SELECT * FROM my_table;
    -[ RECORD 1 ]-
    first  | 1
    second | one
    -[ RECORD 2 ]-
    first  | 2
    second | two
    -[ RECORD 3 ]-
    first  | 3
    second | three
    -[ RECORD 4 ]-
    first  | 4
    second | four

Also, these output format options can be set for just one query by using
`\g`:

    peter@localhost testdb=> SELECT * FROM my_table
    peter@localhost testdb-> \g (format=aligned tuples_only=off expanded=on)
    -[ RECORD 1 ]-
    first  | 1
    second | one
    -[ RECORD 2 ]-
    first  | 2
    second | two
    -[ RECORD 3 ]-
    first  | 3
    second | three
    -[ RECORD 4 ]-
    first  | 4
    second | four

Here is an example of using the `\df` command to find only functions
with names matching `int*pl` and whose second argument is of type
`bigint`:

    testdb=> \df int*pl * bigint
                              List of functions
       Schema   |  Name   | Result data type | Argument data types | Type
    ------------+---------+------------------+---------------------+------
     pg_catalog | int28pl | bigint           | smallint, bigint    | func
     pg_catalog | int48pl | bigint           | integer, bigint     | func
     pg_catalog | int8pl  | bigint           | bigint, bigint      | func
    (3 rows)

When suitable, query results can be shown in a crosstab representation
with the `\crosstabview` command:

    testdb=> SELECT first, second, first > 2 AS gt2 FROM my_table;
     first | second | gt2 
    -------+--------+-----
         1 | one    | f
         2 | two    | f
         3 | three  | t
         4 | four   | t
    (4 rows)

    testdb=> \crosstabview first second
     first | one | two | three | four 
    -------+-----+-----+-------+------
         1 | f   |     |       | 
         2 |     | f   |       | 
         3 |     |     | t     | 
         4 |     |     |       | t
    (4 rows)

This second example shows a multiplication table with rows sorted in
reverse numerical order and columns with an independent, ascending
numerical order.

    testdb=> SELECT t1.first as "A", t2.first+100 AS "B", t1.first*(t2.first+100) as "AxB",
    testdb(> row_number() over(order by t2.first) AS ord
    testdb(> FROM my_table t1 CROSS JOIN my_table t2 ORDER BY 1 DESC
    testdb(> \crosstabview "A" "B" "AxB" ord
     A | 101 | 102 | 103 | 104 
    ---+-----+-----+-----+-----
     4 | 404 | 408 | 412 | 416
     3 | 303 | 306 | 309 | 312
     2 | 202 | 204 | 206 | 208
     1 | 101 | 102 | 103 | 104
    (4 rows)
