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PSQL(1)
NAME
psql - PostgreSQL interactive terminal
SYNOPSIS
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. In addition, it provides a number
of meta-commands and various shell-like features to facilitate writing
scripts and automating a wide variety of tasks.
OPTIONS
-a
--echo-all
Print all input lines to standard output as they are read. This is
more useful for script processing rather than interactive mode. This
is equivalent to setting the variable ECHO to all.
-A
--no-align
Switches to unaligned output mode. (The default output mode is
otherwise aligned.)
-c command
--command command
Specifies that psql is to execute one command string, command, and
then exit. This is useful in shell scripts.
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 with
this option. To achieve that, you could pipe the string into psql,
like this: echo '\x \\ SELECT * FROM foo;' | psql. (\\ is the
separator meta-command.)
If the command string contains multiple SQL commands, they are
processed in a single transaction, unless there are explicit
BEGIN/COMMIT commands included in the string to divide it into
multiple transactions. This is different from the behavior when the
same string is fed to psql's standard input.
-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.
-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 from within psql.
-f filename
--file filename
Use the file filename as the source of commands instead of reading
commands interactively. After the file is processed, psql terminates.
This is in many ways equivalent to the internal command \i.
If filename is - (hyphen), then standard input is read.
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
that you would have gotten 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\!>fR.
-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
Turn on HTML tabular output. 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 internal command \list.
-L filename
--log-file filename
Write all query output into file filename, in addition to the normal
output destination.
-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
Allows you to specify printing options in the style of \pset on the
command line. Note that here you have to separate name and value with
an equal sign instead of a space. Thus 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. Within
psql you can also set the QUIET variable to achieve the same effect.
-R separator
--record-separator separator
Use separator as the record separator for unaligned output. This is
equivalent to the \pset recordsep command.
-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 the \t command.
-T table_options
--table-attr table_options
Allows you to specify options to be placed within the HTML table tag.
See \pset for details.
-u Forces psql to prompt for the user name and password before connecting
to the database.
This option is deprecated, as it is conceptually flawed. (Prompting
for a non-default user name and prompting for a password because the
server requires it are really two different things.) You are
encouraged to look at the -U and -W options instead.
-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 internal 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 just
set a variable without a value, use the equal sign but leave off the
value. These assignments are done during a very early stage of start-
up, so variables reserved for internal purposes might get overwritten
later.
-V
--version
Print the psql version and exit.
-W
--password
Forces psql to prompt for a password before connecting to a database.
psql should automatically prompt for a password whenever the server
requests password authentication. However, currently password request
detection is not totally reliable, hence this option to force a
prompt. If no password prompt is issued and the server requires
password authentication, the connection attempt will fail.
This option will remain set for the entire session, even if you change
the database connection with the meta-command \connect.
-x
--expanded
Turn on the expanded table formatting mode. This is equivalent to the
\x command.
-X,
--no-psqlrc
Do not read the start-up file (neither the system-wide psqlrc file nor
the user's ~/.psqlrc file).
-1
--single-transaction
When psql executes a script with the -f option, adding this option
wraps BEGIN/COMMIT around the script to execute it as a single
transaction. This ensures that either all the commands complete
successfully, or no changes are applied.
If the script itself uses BEGIN, COMMIT, or ROLLBACK, this option will
not have the desired effects. Also, if the script contains any
command that cannot be executed inside a transaction block, specifying
this option will cause that command (and hence the whole transaction)
to fail.
-?
--help
Show help about psql command line arguments, and exit.
EXIT STATUS
psql returns 0 to the shell if it finished normally, 1 if a fatal error of
its own (out of memory, file not found) occurs, 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
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 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 Unix user name, as is the default
database name. Note that you can't 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 in the
documentation.) It is also convenient to have a ~/.pgpass file to avoid
regularly having to type in passwords. See in the documentation for more
information.
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.
ENTERING SQL COMMANDS
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
Welcome to psql 8.2.4, the PostgreSQL interactive terminal.
Type: \copyright for distribution terms
\h for help with SQL commands
\? for help with psql commands
\g or terminate with semicolon to execute query
\q to quit
testdb=>
At the prompt, the user may 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.
Whenever a command is executed, psql also polls for asynchronous
notification events generated by LISTEN [listen(5)] and NOTIFY [notify(5)].
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 help make
psql more useful for administration or scripting. Meta-commands are more
commonly 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 into an argument you may quote it with a single
quote. To include a single quote into such an argument, use two single
quotes. Anything contained in single quotes is furthermore subject to C-
like substitutions for \n (new line), \t (tab), \digits (octal), and
\xdigits (hexadecimal).
If an unquoted argument begins with a colon (:), it is taken as a psql
variable and the value of the variable is used as the argument instead.
Arguments that are enclosed in backquotes (`) are taken as a command line
that is passed to the shell. The output of the command (with any trailing
newline removed) is taken as the argument value. The above escape sequences
also apply in backquotes.
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 when another unquoted backslash occurs. This
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.
The following meta-commands are defined:
........
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.
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.
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.)
Establishes a new connection to a PostgreSQL server. If the new
connection is successfully made, the previous connection is closed. If
any of dbname, username, host or port are omitted or specified as -,
the value of that parameter from the previous connection is used. If
there is no previous connection, the libpq default for the parameter's
value is used.
If the connection attempt failed (wrong user name, access denied,
etc.), the previous connection will only be kept if psql is in
interactive mode. When executing a non-interactive script, processing
will immediately stop with an error. 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.
Performs a frontend (client) copy. This is an operation that runs an
SQL COPY [copy(5)] 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.
The syntax of the command is similar to that of the SQL COPY [copy(5)]
command. Note that, because of this, special parsing rules apply to
the \copy command. In particular, the variable substitution rules and
backslash escapes do not apply.
\copy ... from stdin | to stdout reads/writes based on the command
input and output respectively. All rows are read from the same source
that issued the command, continuing until \. is read or the stream
reaches EOF. Output is sent to the same place as command output. To
read/write from psql's standard input or output, use pstdin or
pstdout. This option is useful for populating tables in-line within a
SQL script file.
Tip: This operation is not as efficient as the SQL COPY command
because all data must pass through the client/server connection. For
large amounts of data the SQL command may be preferable.
Shows the copyright and distribution terms of PostgreSQL.
[ pattern ]
+ [ pattern ]
For each relation (table, view, index, or sequence) matching the
pattern, show all columns, their types, the tablespace (if not the
default) and any special attributes such as NOT NULL or defaults, if
any. Associated indexes, constraints, rules, and triggers are also
shown, as is the view definition if the relation is a view.
(``Matching the pattern'' is defined below.)
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.
Note: If \d is used without a pattern argument, it is equivalent to
\dtvs which will show a list of all tables, views, and sequences. This
is purely a convenience measure.
a [ pattern ]
Lists all available aggregate functions, together with the data types
they operate on. If pattern is specified, only aggregates whose names
match the pattern are shown.
b [ pattern ]
b+ [ pattern ]
Lists all available tablespaces. If pattern is specified, only
tablespaces whose names match the pattern are shown. If + is appended
to the command name, each object is listed with its associated
permissions.
c [ pattern ]
Lists all available conversions between character-set encodings. If
pattern is specified, only conversions whose names match the pattern
are listed.
C Lists all available type casts.
d [ pattern ]
Shows the descriptions of objects matching the pattern, or of all
visible objects if no argument is given. But in either case, only
objects that have a description are listed. (``Object'' covers
aggregates, functions, operators, types, relations (tables, views,
indexes, sequences, large objects), rules, and triggers.) For example:
=> \dd version
Object descriptions
Schema | Name | Object | Description
------------+---------+----------+---------------------------
pg_catalog | version | function | PostgreSQL version string
(1 row)
Descriptions for objects can be created with the COMMENT [comment(5)]
SQL command.
D [ pattern ]
Lists all available domains. If pattern is specified, only matching
domains are shown.
f [ pattern ]
f+ [ pattern ]
Lists available functions, together with their argument and return
types. If pattern is specified, only functions whose names match the
pattern are shown. If the form \df+ is used, additional information
about each function, including language and description, is shown.
Note:
To look up functions taking argument or returning values of a specific
type, use your pager's search capability to scroll through the \df
output.
To reduce clutter, \df does not show data type I/O functions. This is
implemented by ignoring functions that accept or return type cstring.
g [ pattern ]
Lists all database roles. If pattern is specified, only those roles
whose names match the pattern are listed. (This command is now
effectively the same as \du.)
istvS [ pattern ]
This is not the actual command name: the letters i, s, t, v, S stand
for index, sequence, table, view, and system table, respectively. You
can specify any or all of these letters, in any order, to obtain a
listing of all the matching objects. The letter S restricts the
listing to system objects; without S, only non-system objects are
shown. If + is appended to the command name, each object is listed
with its associated description, if any.
If pattern is specified, only objects whose names match the pattern
are listed.
l This is an alias for \lo_list, which shows a list of large objects.
n [ pattern ]
n+ [ pattern ]
Lists all available schemas (namespaces). If pattern (a regular
expression) is specified, only schemas whose names match the pattern
are listed. Non-local temporary schemas are suppressed. If + is
appended to the command name, each object is listed with its
associated permissions and description, if any.
o [ pattern ]
Lists available operators with their operand and return types. If
pattern is specified, only operators whose names match the pattern are
listed.
p [ pattern ]
Produces a list of all available 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 [grant(5)] and REVOKE [revoke(5)] commands are used to set
access privileges.
T [ pattern ]
T+ [ pattern ]
Lists all data types or only those that match pattern. The command
form \dT+ shows extra information.
u [ pattern ]
Lists all database roles, or only those that match pattern.
\dit (or \) [ filename ]
If filename is specified, the file is edited; after the editor exits,
its content is copied back to the query buffer. If no argument is
given, the current query buffer is copied to a temporary file which is
then edited in the same fashion.
The new query buffer is then re-parsed according to the normal rules
of psql, where the whole buffer is treated as a single line. (Thus you
cannot make scripts this way. Use \i for that.) This means also that
if the query ends with (or rather contains) a semicolon, it is
immediately executed. In other cases it will merely wait in the query
buffer.
Tip: psql searches the environment variables PSQL_EDITOR, EDITOR, and
VISUAL (in that order) for an editor to use. If all of them are unset,
vi is used on Unix systems, notepad.exe on Windows systems.
\cho text [ ... ]
Prints the arguments to the standard output, separated by one space
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.
Tip: If you use the \o command to redirect your query output you may
wish to use \qecho instead of this command.
\ncoding [ encoding ]
Sets the client character set encoding. Without an argument, this
command shows the current encoding.
[ string ]
Sets the field separator for unaligned query output. The default is
the vertical bar (|). See also \pset for a generic way of setting
output options.
g [ { filename | |command } ]
Sends the current query input buffer to the server and optionally
stores the query's output in filename or pipes the output into a
separate Unix shell executing command. A bare \g is virtually
equivalent to a semicolon. A \g with argument is a ``one-shot''
alternative to the \o command.
p (or [ 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.
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 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 filename
Reads input from the file filename and executes it as though it had
been typed on the keyboard.
Note: If you want to see the lines on the screen as they are read you
must set the variable ECHO to all.
96. br (or
0. br List the names, owners, and character set encodings of all the
databases in the server. If + is appended to the command name,
database descriptions are also displayed.
rt 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.
rt 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 one ought to remember if one wants to access the object ever
again. For that reason it is recommended to always associate a human-
readable comment with every object. Those can then be seen 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.
0. br Shows a list of all PostgreSQL large objects currently stored
in the database, along with any comments provided for them.
id Deletes the large object with OID loid from the database.
Tip: Use \lo_list to find out the large object's OID.
[ {filename | |command} ]
Saves future query results to the file filename or pipes future
results into a separate Unix shell to execute command. If no arguments
are specified, the query output will be reset to the standard output.
``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.
Print
the current query buffer to the standard output.
assword [ 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.
set parameter [ value ]
This command sets options affecting the output of query result tables.
parameter describes which option is to be set. The semantics of value
depend thereon.
Adjustable printing options are:
format
Sets the output format to one of unaligned, aligned, html, latex, or
troff-ms. Unique abbreviations are allowed. (That would mean one
letter is enough.)
``Unaligned'' writes all columns of a row on a line, separated by
the currently active field separator. This is intended to create
output that might be intended to be read in by other programs (tab-
separated, comma-separated). ``Aligned'' mode is the standard,
human-readable, nicely formatted text output that is default. The
``HTML'' and ``LaTeX'' modes 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 so dramatic in HTML,
but in LaTeX you must have a complete document wrapper.)
border
The second argument must be a number. In general, the higher the
number the more borders and lines the tables will have, but this
depends on the particular format. In HTML mode, this will translate
directly into the border=... attribute, in the others only values 0
(no border), 1 (internal dividing lines), and 2 (table frame) make
sense.
expanded (or x)
Toggles between regular and expanded format. When expanded format 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.
Expanded mode is supported by all four output formats.
null
The second argument is a string that should be printed whenever a
column is null. The default is not to print anything, which can
easily be mistaken for, say, an empty string. Thus, one might choose
to write \pset null '(null)'.
fieldsep
Specifies the field separator to be used in unaligned output mode.
That way one can create, for example, tab- or comma-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).
footer
Toggles the display of the default footer (x rows).
numericlocale
Toggles the display of a locale-aware character to separate groups
of digits to the left of the decimal marker. It also enables a
locale-aware decimal marker.
recordsep
Specifies the record (line) separator to use in unaligned output
mode. The default is a newline character.
tuples_only (or t)
Toggles between tuples only and full display. Full display may show
extra information such as column headers, titles, and various
footers. In tuples only mode, only actual table data is shown.
title [ text ]
Sets the table title for any subsequently printed tables. This can
be used to give your output descriptive tags. If no argument is
given, the title is unset.
tableattr (or T) [ text ]
Allows you to specify any attributes to be placed inside the HTML
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.
pager
Controls use of a pager for query and psql help output. If the
environment variable PAGER is set, the output is piped to the
specified program. Otherwise a platform-dependent default (such as
more) is used.
When the pager is off, the pager is not used. When the pager is on,
the pager is used only when appropriate, i.e. the output is to a
terminal and will not fit on the screen. (psql does not do a
perfect job of estimating when to use the pager.) \pset pager turns
the pager on and off. Pager can also be set to always, which causes
the pager to be always used.
Illustrations on how these different formats look can be seen in the
Examples [psql(1)] section.
Tip: There are various shortcut commands for \pset. See \a, \C, \H,
\t, \T, and \x.
Note: It is an error to call \pset without arguments. In the future
this call might show the current status of all printing options.
q Quits the psql program.
qecho text [ ... ]
This command is identical to \echo except that the output will be
written to the query output channel, as set by \o.
Resets (clears) the query buffer.
[ filename ]
Print or save the command line history to filename. If filename is
omitted, the history is written to the standard output. This option is
only available if psql is configured to use the GNU Readline library.
t [ name [ value [ ... ] ] ]
Sets the internal variable name to value or, if more than one value is
given, to the concatenation of all of them. If no second argument is
given, the variable is just set with no value. To unset a variable,
use the \unset command.
Valid variable names can contain characters, digits, and underscores.
See the section Variables [psql(1)] below for details. Variable names
are case-sensitive.
Although you are welcome to set any variable to anything you want,
psql treats several variables as special. They are documented in the
section about variables.
Note: This command is totally separate from the SQL command SET
[set(5)].
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
Allows you to specify attributes to be placed within the table tag in
HTML tabular output mode. This command is equivalent to \pset
tableattr table_options.
iming
Toggles a display of how long each SQL statement takes, in
milliseconds.
{filename | |command}
Outputs the current query buffer to the file filename or pipes it to
the Unix command command.
120. br Toggles expanded table formatting mode. As such it is
equivalent to \pset expanded.
[ pattern ]
Produces a list of all available 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.
The GRANT [grant(5)] and REVOKE [revoke(5)] commands are used to set
access privileges.
This is an alias for \dp (``display privileges'').
[ command ]
Escapes to a separate Unix shell or executes the Unix command command.
The arguments are not further interpreted, the shell will see them as
is.
? Shows help information about the backslash commands.
PATTERNS
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.
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 all 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 starts with 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 in the documentation, except for .
which is taken as a separator as mentioned above, * which is translated to
the regular-expression notation .*, and ? which is translated to .. You can
emulate these pattern characters at need by writing ? for ., (R+|) for R*,
or (R|) for R?. Remember that the pattern must match the whole name,
unlike the usual interpretation of regular expressions; 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).
Whenever the pattern parameter is omitted completely, the \d commands
display all objects that are visible in the current schema search path -
this is equivalent to using the pattern *. To see all objects in the
database, use the pattern *.*.
ADVANCED FEATURES
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. To set variables, use the psql meta-command \set:
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 and use it as the argument of any
slash command:
testdb=> \echo :foo
bar
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.
If you call \set without a second argument, the variable is set, with an
empty string as value. To unset (or delete) a variable, use the command
\unset.
psql's internal variable names can consist of letters, numbers, and
underscores in any order and any number of them. A number of these
variables are treated specially by psql. They indicate certain option
settings that can be changed at run time by altering the value of the
variable or represent some state of the application. Although you can use
these variables for any other purpose, this is not recommended, as the
program behavior might grow really strange really quickly. By convention,
all specially treated variables consist of all upper-case letters (and
possibly numbers and underscores). To ensure maximum compatibility in the
future, avoid using such variable names for your own purposes. A list of
all specially treated variables follows.
AUTOCOMMIT
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 may wish to set it in the system-wide psqlrc file or your
~/.psqlrc file.
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 unset.
ECHO If set to all, all lines entered from the keyboard or from a script
are written to the standard output before they are parsed or executed.
To select this behavior on program start-up, use the switch -a. If set
to queries, psql merely prints all queries as they are sent to the
server. The switch for this is -e.
ECHO_HIDDEN
When this variable is set and a backslash command queries the
database, the query is first shown. This way you can study the
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 the variable to the value noexec, the queries are just
shown but are not actually sent to the server and executed.
ENCODING
The current client character set encoding.
FETCH_COUNT
If this variable is set to an integer value > 0, 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 may 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.
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 unset, or if set to
any other value than those above, 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. The default
value is ~/.psql_history. 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 number of commands to store in the command history. The default
value is 500.
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 unset.
IGNOREEOF
If unset, sending an EOF character (usually Control+D) to an
interactive session of psql will terminate the application. If set to
a numeric value, that many EOF characters are ignored before the
application terminates. If the variable is set but has no numeric
value, the default is 10.
Note: This feature was shamelessly plagiarized from Bash.
LASTOID
The value of the last affected OID, as returned from an INSERT or
lo_insert command. This variable is only guaranteed to be valid until
after the result of the next SQL command has been displayed.
ON_ERROR_ROLLBACK
When on, if a statement in a transaction block generates an error, the
error is ignored and the transaction continues. When interactive, such
errors are only ignored in interactive sessions, and not when reading
script files. When off (the default), a statement in a transaction
block that generates an error aborts the entire transaction. The
on_error_rollback-on mode works by issuing an implicit SAVEPOINT for
you, just before each command that is in a transaction block, and
rolls back to the savepoint on error.
ON_ERROR_STOP
By default, if non-interactive scripts encounter an error, such as a
malformed SQL command or internal meta-command, processing continues.
This has been the traditional behavior of psql but it is sometimes not
desirable. If this variable is set, script processing will immediately
terminate. If the script was called from another script it will
terminate in the same fashion. If the outermost script was not called
from an interactive psql session but rather using the -f option, psql
will return error code 3, to distinguish this case from fatal error
conditions (error code 1).
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 unset.
PROMPT1
PROMPT2
PROMPT3
These specify what the prompts psql issues should look like. See
Prompting [psql(1)] below.
QUIET
This variable is equivalent to the command line option -q. It is
probably not too useful in interactive mode.
SINGLELINE
This variable is equivalent to the command line option -S.
SINGLESTEP
This variable is equivalent to the command line option -s.
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 unset.
VERBOSITY
This variable can be set to the values default, verbose, or terse to
control the verbosity of error reports.
SQL INTERPOLATION
An additional useful feature of psql variables is that you can substitute
(``interpolate'') them into regular SQL statements. The syntax for this is
again to prepend the variable name with a colon (:).
testdb=> \set foo 'my_table'
testdb=> SELECT * FROM :foo;
would then query the table my_table. The value of the variable is copied
literally, so it can even contain unbalanced quotes or backslash commands.
You must make sure that it makes sense where you put it. Variable
interpolation will not be performed into quoted SQL entities.
A popular application of this facility is to refer to the last inserted OID
in subsequent statements to build a foreign key scenario. Another possible
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 proceed as above.
testdb=> \set content '''' `cat my_file.txt` ''''
testdb=> INSERT INTO my_table VALUES (:content);
One problem with this approach is that my_file.txt might contain single
quotes. These need to be escaped so that they don't cause a syntax error
when the second line is processed. This could be done with the program sed:
testdb=> \set content '''' `sed -e "s/'/''/g" < my_file.txt` ''''
If you are using non-standard-conforming strings then you'll also need to
double backslashes. This is a bit tricky:
testdb=> \set content '''' `sed -e "s/'/''/g" -e 's/\\/\\\\/g' < my_file.txt` ''''
Note the use of different shell quoting conventions so that neither the
single quote marks nor the backslashes are special to the shell.
Backslashes are still special to sed, however, so we need to double them.
(Perhaps at one point you thought it was great that all Unix commands use
the same escape character.)
Since colons may legally appear in SQL commands, the following rule
applies: the character sequence ``:name'' is not changed unless ``name'' is
the name of a variable that is currently set. In any case you can escape a
colon with a backslash to protect it from substitution. (The colon syntax
for variables is standard SQL for embedded query languages, such as ECPG.
The colon syntax for array slices and type casts are PostgreSQL extensions,
hence the conflict.)
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 input because the command
was not terminated with a semicolon or a quote was not closed. Prompt 3 is
issued when you run an SQL COPY command and you are expected to type in the
row values 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.)
%R In prompt 1 normally =, but ^ if in single-line mode, and ! if the
session is disconnected from the database (which can happen if
\connect fails). In prompt 2 the sequence is replaced by -, *, a
single quote, a double quote, or a dollar sign, depending on whether
psql expects more input because the command wasn't terminated yet,
because you are inside a /* ... */ comment, or because you are inside
a quoted or dollar-escaped string. In prompt 3 the sequence 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).
%digits
The character with the indicated octal code is substituted.
%:name:
The value of the psql variable name. See the section Variables
[psql(1)] for details.
%`command`
The output of command, similar to ordinary ``back-tick'' substitution.
%[ ... %]
Prompts may 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 may 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.
To insert a percent sign into your prompt, write %%. The default prompts
are '%/%R%# ' for prompts 1 and 2, and '>> ' for prompt 3.
Note: This feature was shamelessly plagiarized from tcsh.
COMMAND-LINE EDITING
psql supports the Readline library for convenient line editing and
retrieval. The command history is automatically saved when psql exits and
is reloaded when psql starts up. Tab-completion is also supported, although
the completion logic makes no claim to be an SQL parser. If for some reason
you do not like the tab completion, you can turn it off 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.)
ENVIRONMENT
PAGER
If the query results do not fit on the screen, they are piped through
this command. Typical values are more or less. The default is
platform-dependent. The use of the pager can be disabled by using the
\pset command.
PGDATABASE
Default connection database
PGHOST
PGPORT
PGUSER
Default connection parameters
PSQL_EDITOR
EDITOR
VISUAL
Editor used by the \e command. The variables are examined in the order
listed; the first that is set is used.
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 in the documentation).
FILES
· Before starting up, psql attempts to read and execute commands from the
system-wide psqlrc file and the user's ~/.psqlrc file. (On Windows, the
user's startup file is named %APPDATA%\postgresql\psqlrc.conf.) See
PREFIX/share/psqlrc.sample for information on setting up the system-wide
file. It could be used to set up the client or the server to taste (using
the \set and SET commands).
· Both the system-wide psqlrc file and the user's ~/.psqlrc file can be
made version-specific by appending a dash and the PostgreSQL release
number, for example ~/.psqlrc-8.2.4. A matching version-specific file
will be read in preference to a non-version-specific file.
· The command-line history is stored in the file ~/.psql_history, or
%APPDATA%\postgresql\psql_history on Windows.
NOTES
· In an earlier life psql allowed the first argument of a single-letter
backslash command to start directly after the command, without
intervening whitespace. For compatibility this is still supported to some
extent, but we are not going to explain the details here as this use is
discouraged. If you get strange messages, keep this in mind. For example
testdb=> \foo
Field separator is "oo".
which is perhaps not what one would expect.
· psql only works smoothly with servers of the same version. That does not
mean other combinations will fail outright, but subtle and not-so-subtle
problems might come up. Backslash commands are particularly likely to
fail if the server is of a different version.
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
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 "my_table"
Attribute | Type | Modifier
-----------+---------+--------------------
first | integer | not null default 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 unaligned
Output format is unaligned.
peter@localhost testdb=> \pset fieldsep ","
Field separator is ",".
peter@localhost testdb=> \pset tuples_only
Showing only tuples.
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
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Alphabetical
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