psql
psql — PostgreSQL 互動式終端介面
語法
psql [option...] [dbname [username]]
說明
psql 是 PostgreSQL 的終端機介面的前端工具。它讓您能夠以互動式輸入查詢指令，將它們發送到 PostgreSQL，並查看查詢結果。還有，輸入可以來自檔案或命令列參數。此外，psql 提供了許多自有指令以及各種類似 shell 的功能，以便於撰寫腳本以自動執行各種任務。
Options
-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 otherwise 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 psqlmeta-commands within a -c option. To achieve that, you could use repeated -c options or pipe the string into psql, for example:
or
(\\ 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 Section 53.2.2.1 for more details about how the server handles multi-query strings.) Also, psql only prints the result of the last SQL command in the string. This is different from the behavior when the same string is read from a file or fed to psql's standard input, because then psql sends each SQL command separately.
Because of this behavior, putting more than one SQL command in a single -c string often has unexpected results. It's better to 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:
-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.
If this parameter contains an = sign or starts with a valid URI prefix (postgresql:// or postgres://), it is treated as a conninfo string. See Section 34.1.1 for more information.
-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
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 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. This can be useful to turn off tab expansion when cutting and pasting.
-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 by other means 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.
This option is never essential, since psql will automatically prompt for a password if the server demands password authentication. 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
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 Section 34.14.) It is also convenient to have a ~/.pgpass file to avoid regularly having to type in passwords. See Section 34.15 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:
This way you can also use LDAP for connection parameter lookup as described in Section 34.17. See Section 34.1.2 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
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:
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, begin your session by removing publicly-writable schemas from search_path. One can addoptions=-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 topsql; 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 and NOTIFY.
While C-style block comments are passed to the server for processing and removal, SQL-standard comments are removed by 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 \xdigits (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. 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:_variablename` 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, or using conninfo connection strings as detailed in Section 34.1.1.
Where the command omits database name, user, host, or port, the new connection can reuse values from the previous connection. By default, values from the previous connection are reused except when processing a conninfo string. Passing a first argument of -reuse-previous=on or -reuse-previous=off overrides that default. When the command neither specifies nor reuses a particular parameter, the libpq default is used. Specifying any of dbname, username, host or port as - is equivalent to omitting that parameter.
If the new connection is successfully made, the previous connection is closed. If the connection attempt failed (wrong user name, access denied, etc.), the previous connection will only be kept ifpsql 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.
Examples:
\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 ) ] | ( query ) } { from | to } { 'filename' | program 'command' | stdin | stdout | pstdin | pstdout } [ [ with ] ( option [, ...] ) ]
執行前端（用戶端）資料複製。這是一個執行 SQL COPY 命令的操作，但不是由伺服器讀取或寫入指定的檔案，psql 讀取或寫入檔案並在伺服器和本地檔案系統之間傳輸資料。這意味著檔案可存取性和權限是本地使用者的權限，而不是伺服器，並且不需要 SQL 超級使用者權限。
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 a 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 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
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 SQLcommand 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 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 setting.
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.
\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.
\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 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 command is used to set default access privileges. The meaning of the privilege display is explained under GRANT.
\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, \dit lists indexes and tables. If + is appended to the command name, each object is listed with its physical size on disk and its 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 ACL, 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 ACL, options, and description of the foreign-data wrapper are also shown.
\df[anptwS+] [ 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. 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.
Tip
To look up functions taking arguments or returning values of a specific data type, use your pager's search capability to scroll through the \df output.\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 Smodifier 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.
\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 ]
Lists operators with their operand and result types. If pattern is specified, only operators 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, 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 and REVOKE commands are used to set access privileges. The meaning of the privilege display is explained under GRANT.
\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 and ALTER DATABASE 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 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 Smodifier 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.
\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.
The new contents of the query buffer are then 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. Whatever remains will wait in the query buffer; 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 under Environment for how to configure and customize your editor.
\echo 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:
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 might wish to use \qecho instead of this command.\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. After the editor exits, the updated command waits in the query buffer; 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 under Environment 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. After the editor exits, the updated command waits in the query buffer; 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 [ filename ]
\g [ |command ]
Sends the current query buffer to the server for execution. If an 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 an argument is essentially equivalent to a semicolon. A \g with argument is a “one-shot” alternative to the \o command.
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.
\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.
\gexec
Sends the current query buffer to the server, then treats each column of each row of the query's output (if any) as a SQL statement to be executed. For example, to create an index on each column of my_table:
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). 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:
If you specify a prefix, that string is prepended to the query's column names to create the variable names to use:
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 [ filename ]
\gx [ |command ]
\gx is equivalent to \g, but forces expanded output mode for this query. See \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 \psetabout 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:
\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:
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.
\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 thewrapped format only affects screen output. If columns is nonzero then file and pipe output is wrapped to that width as well.
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- 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).
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 unaligned, aligned, wrapped, html, asciidoc, latex (uses tabular), latex-longtable, or troff-ms. Unique abbreviations are allowed. (That would mean one letter is enough.)
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).
aligned format is the standard, human-readable, nicely formatted text output; this is the default.
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 html, asciidoc, 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. latex-longtable also requires the LaTeX longtable and booktabspackages.
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 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 the Examples section.
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 the section 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, below.
Note
This command is unrelated to the SQL command SET.
\setenv name [ value ]
Sets the environment variable name to value, or if the value is not supplied, unsets the environment variable. Example:
\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, 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.
\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 a 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
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
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 Section 53.2.2.1 for more details about how the server handles multi-query strings.) psql prints only the last query result it receives for each request; in this example, although all three SELECTs are indeed executed, psql only prints the 3.
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.
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 * 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 Section 9.7.3, 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
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,
sets the variable foo to the value bar. To retrieve the content of the variable, precede the name with a colon, for example:
This works in both regular SQL commands and meta-commands; there is more detail in SQL 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
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 orpreserve-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 alignedformat 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 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:
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) 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.
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
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 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_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. (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 Appendix A) 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, or terse 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
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,
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:
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:
(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
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 the section Variables 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:
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. The queries generated by tab-completion can also interfere with other SQL commands, e.g. SET TRANSACTION ISOLATION LEVEL. 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:
(This is not a psql but a Readline feature. Read its documentation for further details.)
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 Section 34.14).
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 ornotepad.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 Emacsor 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:
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.
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 Section 34.14).
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
\dfamily 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 psqlfrom 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
-coption 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
The first example shows how to spread a command over several lines of input. Notice the changing prompt:
Now look at the table definition again:
Now we change the prompt to something more interesting:
Let's assume you have filled the table with data and want to take a look at it:
You can display tables in different ways by using the \pset command:
Alternatively, use the short commands:
When suitable, query results can be shown in a crosstab representation with the \crosstabview command:
This second example shows a multiplication table with rows sorted in reverse numerical order and columns with an independent, ascending numerical order.
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