HomeMogDBMogDB StackUqbar
Ecological Tools
Doc Tools
中文
v5.0

Documentation:v5.0

Supported Versions:
Current(v5.0)/
v3.1

Other Versions:
v3.0/
v2.1/
v2.0/
v1.1

Meta-Command Reference

This section describes meta-commands provided by gsql after the MogDB database CLI tool is used to connect to a database. A gsql meta-command can be anything that you enter in gsql and begins with an unquoted backslash.

Precautions

  • The format of the gsql meta-command is a backslash () followed by a command verb, and then a parameter. The parameters are separated from the command verb and from each other by any number of whitespace characters.
  • To include whitespace in a parameter, you can quote it with single quotation marks ("). To include single quotation marks in a parameter, add a backslash in front of it. Anything contained in single quotation marks 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).
  • Within a parameter, text enclosed in double quotation marks ("") is taken as a command line input to the shell. The command output (with any trailing newline removed) is taken as a parameter.
  • If an unquoted parameter begins with a colon (:), the parameter is taken as a gsql variable and the value of the variable is used as the parameter value instead.
  • Some commands take an SQL identifier (such as a table name) as a parameter. These parameters follow the SQL syntax rules: Unquoted letters are forced to lowercase, while double quotation marks ("") protect letters from case conversion and allow incorporation of whitespace into the identifier. Within double quotation marks, paired double quotation marks reduce to a single double quotation mark in the result name. For example, FOO"BAR"BAZ is interpreted as fooBARbaz, and "Aweird""name" becomes A weird"name.
  • Parameter parsing stops when another unquoted backslash appears. An unquoted backslash is taken as the beginning of a new meta-command. The special sequence \ (two backslashes) marks the end of parameters and continues parsing SQL statements if any. In this way, SQL statements and gsql commands can be freely mixed in a line. However, the parameters of a meta-command cannot continue beyond the end of a line in any situations.

Meta-Commands

For details about meta-commands, see Table Common meta-commands, Table Query buffer meta-commands, Table Input and output meta-commands, Table Information display meta-commands, Table Formatting meta-commands,Table Connection meta-commands , Table OS meta-commands, Table Variable meta-commands, and Table Large object meta-commands.

img NOTICE: FILE mentioned in the following commands indicates a file path. This path can be an absolute path such as /home/gauss/file.txt or a relative path, such as file.txt. By default, a file.txt is created in the path where the user runs gsql commands.

Table 1 Common meta-commands

Parameter Description Value Range
\copyright Displays the MogDB version and copyright information. -
\g [FILE] or ; Performs a query operation and sends the result to a file or pipe. -
\h(\help) [NAME] Provides syntax help on the specified SQL statement. If NAME is not specified, then gsql will list all the commands for which syntax help is available.
If NAME is an asterisk (*), syntax help on all SQL statements is displayed.
\parallel [on [num]|off] Controls the parallel execution function.
- on: The switch is enabled and the maximum number of concurrently executed tasks is num.
- off: This switch is disabled.
NOTE:
- Parallel execution is not allowed in a running transaction and a transaction is not allowed to be stared during parallel execution.
- Parallel execution of \d meta-commands is not allowed.
- If SELECT statements are run concurrently, customers can accept the problem that the return results are displayed randomly but they cannot accept it if a core dump or process response failure occurs.
- SET statements are not allowed in concurrent tasks because they may cause unexpected results.
- Temporary tables cannot be created. If temporary tables are required, create them before parallel execution is enabled, and use them only in the parallel execution. Temporary tables cannot be created in parallel execution.
- When \parallel is executed, num independent gsql processes can be connected to the database server.
- The duration of all the jobs specified using \parallel cannot exceed session_timeout. Otherwise, the database may be disconnected during parallel execution.
- One or more commands following \parallel on are executed only after \parallel off is executed. Therefore, each \parallel on must correspond to one \parallel off. Otherwise, the commands following \parallel on cannot be executed.		 The default value of num is 1024.
NOTICE:
- The maximum number of connections allowed by the server is determined based on max_connection and the number of current connections.
- Set the value of num based on the allowed number of connections.
\q Exits the gsql program. In a script file, this command is run only when a script terminates. -

Table 2 Query buffer meta-commands

Parameter Description
\e [FILE] [LINE] Uses an external editor to edit the query buffer or file.
\ef [FUNCNAME [LINE]] Uses an external editor to edit the function definition. If LINE is specified, the cursor will point to the specified line of the function body.
\p Prints the current query buffer to the standard output.
\r Resets (clears) the query buffer.
\w FILE Outputs the current query buffer to a file.

Table 3 Input and output meta-commands

Parameter Description
\copy { table [ ( column_list ) ] | ( query ) } { from | to } { filename | stdin | stdout | pstdin | pstdout } [ with ] [ binary ] [ oids ] [ delimiter [ as ] 'character' ] [ null [ as ] 'string' ] [ csv [ header ] [ quote [ as ] 'character' ] [ escape [ as ] 'character' ] [ force quote column_list | * ] [ force not null column_list ] ] [parallel integer] After logging in to the database on any psql client, you can import and export data. This is an operation of running the SQL COPY command, but not the server that reads or writes data to a specified file. Instead, data is transferred between the server and the local file system. This means that the accessibility and permissions of the file are the permissions of the local user rather than the server. The initial database user permission is not required.
NOTE:
\COPY applies only to small-scale data import in good format. It does not preprocess invalid characters or provide error tolerance. COPY is preferred for data import.
\COPY specifies the number of clients to import data to implement parallel import of data files. Currently, the value ranges from 1 to 8.
The parallel import using \COPY has the following constraints: Parallel import of temporary tables is not supported. Parallel import within transactions is not supported. Parallel import of binary files is not supported. Parallel import of data encrypted using AES-128 is not supported. In these cases, even if the parallel parameter is specified, a non-parallel process is performed.
\echo [STRING] Writes a character string to the standard output.
\i FILE Reads content from FILE and uses them as the input for a query.
\i+ FILE KEY Runs commands in an encrypted file.
\ir FILE Is similar to \i, but resolves relative path names differently.
\ir+ FILE KEY Is similar to \i+, but resolves relative path names differently.
\o [FILE] Saves all query results to a file.
\qecho [STRING] Prints a character string to the query result output.

img NOTE: In Table 4, option S indicates displaying the system object and PATTERN indicates displaying the additional description information and the name of the object to be displayed.

Table 4 Information display meta-commands

Parameter Description Value Range Example
\d[S+] Lists all tables, views, and sequences of all schemas in search_path. When objects with the same name exist in different schemas in search_path, only the object in the schema that ranks first in search_path is displayed. - List all tables, views, and sequences of all schemas in search_path.
mogdb=# \d
\d[S+] NAME Lists the structure of specified tables, views, and indexes. - List the structure of table a.
mogdb=# \dtable+ a
\d+ [PATTERN] Lists all tables, views, and indexes. If PATTERN is specified, only tables, views, and indexes whose names match PATTERN are displayed. List all tables, views, and indexes whose names start with f.
mogdb=# \d+ f
\da[S] [PATTERN] Lists all available aggregate functions, together with their return value types and the data types. If PATTERN is specified, only aggregate functions whose names match PATTERN are displayed. List all available aggregate functions whose names start with f, together with their return value types and the data types.
mogdb=# \da f
\db[+] [PATTERN] Lists all available tablespaces. If PATTERN is specified, only tablespaces whose names match PATTERN are displayed. List all available tablespaces whose names start with p.
mogdb=# \db p*
\dc[S+] [PATTERN] Lists all available conversions between character sets. If PATTERN is specified, only conversions whose names match PATTERN are displayed. List all available conversions between character sets.
mogdb=# \d
\dC[+] [PATTERN] Lists all type conversions. If PATTERN is specified, only conversions whose names match PATTERN are displayed. List all type conversion whose patten names start with c# \dC c
\dd[S] [PATERN] Lists descriptions about objects matching PATTERN. If PATTERN is not specified, all visible objects are displayed. The objects include aggregations, functions, operators, types, relations (table, view, index, sequence, and large object), and rules. List all visible objects.
mogdb=# \dd
\ddp [PATTERN] Lists all default permissions. If PATTERN is specified, only permissions whose names match PATTERN are displayed. List all default permissions.
mogdb=# \ddp
\dD[S+] [PATTERN] Lists all available domains. If PATTERN is specified, only domains whose names match PATTERN are displayed. List all available domains.
mogdb=# \dD
\ded[+] [PATTERN] Lists all Data Source objects. If PATTERN is specified, only objects whose names match PATTERN are displayed. List all Data Source objects.
mogdb=# \ded
\det[+] [PATTERN] Lists all external tables. If PATTERN is specified, only tables whose names match PATTERN are displayed. List all external tables.
mogdb=# \det
\des[+] [PATTERN] Lists all external servers. If PATTERN is specified, only servers whose names match PATTERN are displayed. List all external servers.
mogdb=# \des
\deu[+] [PATTERN] Lists user mappings. If PATTERN is specified, only mappings whose names match PATTERN are displayed. List user mappings.
mogdb=# \deu
\dew[+] [PATTERN] Lists foreign-data wrappers. If PATTERN is specified, only wrappers whose names match PATTERN are displayed. List foreign-data wrappers.
mogdb=# \dew
\df[antw][S+] [PATTERN] Lists all available functions, together with their parameters and return types. a indicates an aggregate function, n indicates a common function, t indicates a trigger, and w indicates a window function. If PATTERN is specified, only functions whose names match PATTERN are displayed. List all available functions, together with their parameters and return types.
mogdb=# \df
\dF[+] [PATTERN] Lists all text search configurations. If PATTERN is specified, only configurations whose names match PATTERN are displayed. List all text search configurations.
mogdb=# \dF+
\dFd[+] [PATTERN] Lists all text search dictionaries. If PATTERN is specified, only dictionaries whose names match PATTERN are displayed. List all text search dictionaries.
mogdb=# \dFd
\dFp[+] [PATTERN] Lists all text search parsers. If PATTERN is specified, only parsers whose names match PATTERN are displayed. List all text search parsers.
mogdb=# \dFp
\dFt[+] [PATTERN] Lists all text search templates. If PATTERN is specified, only templates whose names match PATTERN are displayed. List all text search templates.
mogdb=# \dFt
\dg[+] [PATTERN] Lists all database roles.
NOTE:
Since the concepts of "users" and "groups" have been unified into "roles", this command is now equivalent to \du. The two commands are all reserved for forward compatibility.		 If PATTERN is specified, only roles whose names match PATTERN are displayed. List all database roles whose names start with j and end with e.
mogdb=# \dg j?e
\dl An alias for \lo_list, which shows a list of large objects. - List all large objects.
mogdb=# \dl
\dL[S+] [PATTERN] Lists available procedural languages. If PATTERN is specified, only languages whose names match PATTERN are displayed. List available procedural languages.
mogdb=# \dL
\dn[S+] [PATTERN] Lists all schemas (namespace). If PATTERN is specified, only schemas whose names match PATTERN are displayed. By default, only schemas you created are displayed. List information about all schemas whose names start with d.
mogdb=# \dn+ d
\do[S] [PATTERN] Lists all available operators with their operand and return types. If PATTERN is specified, only operators whose names match PATTERN are displayed. By default, only operators you created are displayed. List all available operators with their operand and return types.
mogdb=# \do
\dO[S+] [PATTERN] Lists collations. If PATTERN is specified, only collations whose names match PATTERN are displayed. By default, only collations you created are displayed. List collations.
mogdb=# \dO
\dp [PATTERN] Lists tables, views, and related permissions.
The following result about \dp is displayed:
rolename=xxxx/yyyy - Assigning permissions to a role
=xxxx/yyyy -Assigning permissions to public
xxxx indicates assigned permissions, and yyyy indicates roles with the assigned permissions. For details about permission descriptions, see Table Description of permissions.		 If PATTERN is specified, only tables and views whose names match PATTERN are displayed. List tables, views, and related permissions.
mogdb=# \dp
\drds [PATTERN1 [PATTERN2]] Lists all modified configuration parameters. These settings can be for roles, for databases, or for both. PATTERN1 and PATTERN2 indicate a role pattern and a database pattern, respectively. If PATTERN is specified, only collations whose names match PATTERN are displayed. If the default value is used or is specified, all settings are listed. List all modified configuration parameters of the mogdb database.
mogdb=# \drds * mogdb
\dT[S+] [PATTERN] Lists all data types. If PATTERN is specified, only types whose names match PATTERN are displayed. List all data types.
mogdb=# \dT
\du[+] [PATTERN] Lists all database roles.
NOTE:
Since the concepts of "users" and "groups" have been unified into "roles", this command is now equivalent to \dg. The two commands are all reserved for forward compatibility.		 If PATTERN is specified, only roles whose names match PATTERN are displayed. List all database roles.
mogdb=# \du
\dE[S+] [PATTERN]\di[S+] [PATTERN]\ds[S+] [PATTERN]\dt[S+] [PATTERN]\dv[S+] [PATTERN] In this group of commands, the letters E, i, s, t, and v stand for a foreign table, index, sequence, table, or view, respectively. You can specify any or a combination of these letters sequenced in any order to obtain an object list. For example, \dit lists all indexes and tables. If a command is suffixed with a plus sign (+), physical dimensions and related descriptions of each object will be displayed. If PATTERN is specified, only objects whose names match PATTERN are displayed. By default, only objects you created are displayed. You can specify PATTERN or S to view other system objects. List all indexes and views.
mogdb=# \div
\dx[+] [PATTERN] Lists the extensions of the installed database. If PATTERN is specified, only extensions whose names match PATTERN are displayed. List the extensions of the installed database.
mogdb=# \dx
\l[+] Lists the names, owners, character set encodings, and permissions of all the databases in the server. - List the names, owners, character set encodings, and permissions of all the databases in the server.
mogdb=# \l
\sf[+] FUNCNAME Displays function definitions.
NOTE:
If the function name contains parentheses, enclose the function name with quotation marks and add the parameter type list following the double quotation marks. Also enclose the list with parentheses.		 - Assume a function function_a and a function func()name. This parameter will be as follows:
mogdb=# \sf function_a mogdb=# \sf "func()name"(argtype1, argtype2)
\z [PATTERN] Lists all tables, views, and sequences in the database and their access permissions. If a pattern is given, it is a regular expression, and only matched tables, views, and sequences are displayed. List all tables, views, and sequences in the database and their access permissions.
mogdb=# \z

Table 5 Description of permissions

Parameter Description
r SELECT: allows you to read data from specified tables and views.
w UPDATE: allows you to update columns for specified tables.
a INSERT: allows you to insert data to specified tables.
d DELETE: allows you to delete data from specified tables.
D TRUNCATE: allows you to delete all data from specified tables.
x REFERENCES: allows you to create foreign key constraints. This parameter does not take effect because foreign keys are not supported.
t TRIGGER: allows you to create a trigger on specified tables.
X EXECUTE: allows you to use specified functions and the operators that are realized by the functions.
U USAGE:
- For procedural languages, allows you to specify a procedural language when creating a function.
- For schemas, allows you to access objects included in specified schemas.
- For sequences, allows you to use the nextval function.
C CREATE:
- For databases, allows you to create schemas within a database.
- For schemas, allows you to create objects in a schema.
- For tablespaces, allows you to create tables in a tablespace and set the tablespace to default one when creating databases and schemas.
c CONNECT: allows you to access specified databases.
T TEMPORARY: allows you to create temporary tables.
A ALTER: allows users to modify the attributes of a specified object.
P DROP: allows users to delete a specified object.
m COMMENT: allows users to define or modify comments of a specified object.
i INDEX: allows users to create indexes on specified tables.
v VACUUM: allows users to perform ANALYZE and VACUUM operations on specified tables.
* Authorization options for preceding permissions.

Table 6 Formatting meta-commands

Parameter Description
\a Controls the switchover between unaligned mode and aligned mode.
\C [STRING] Sets the title of any table being printed as the result of a query or cancels such a setting.
\f [STRING] Sets a field separator for unaligned query output.
\H - If the text format schema is used, switches to the HTML format.
- If the HTML format schema is used, switches to the text format.
\pset NAME [VALUE] Sets options affecting the output of query result tables. For details about the value of NAME, see Table Adjustable printing options.
\t [on|off] Switches the information and row count footer of the output column name.
\T [STRING] Specifies attributes to be placed within the table tag in HTML output format. If the parameter is not configured, the attributes are not set.
\x [on|off|auto] Switches expanded table formatting modes.

Table 7 Adjustable printing options

Option Description Value Range
border The value must be a number. In general, a larger number indicates wider borders and more table lines. The value is an integer greater than 0 in HTML format.
The value range in other formats is as follows:
- 0: no border
- 1: internal dividing line
- 2: table frame
expanded (or x) Switches between regular and expanded formats. - When the expanded format is enabled, query results are displayed in two columns, with the column name on the left and the data on the right. This format is useful if the data does not fit the screen in the normal "horizontal" format.
- The expanded format is used when the query output is wider than the screen. Otherwise, the regular format is used. The regular format is effective only in the aligned and wrapped formats.
fieldsep Specifies the field separator to be used in unaligned output format. In this way, you can create tab- or comma-separated output required by other programs. 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 be used in unaligned output format to zero bytes. -
footer Enables or disables the display of table footers. -
format Selects the output format. Unique abbreviations are allowed. (This means a single letter is sufficient.) Value range:
- unaligned: Write all columns of a row on one line, separated by the currently active column separator.
- aligned: This format is standard and human-readable.
- wrapped: This format is similar to aligned, but includes the packaging cross-line width data value to suit the width of the target field output.
- html: This format outputs table to the markup language for a document. The output is not a complete document.
- latex: This format outputs table to the markup language for a document. The output is not a complete document.
- troff-ms: This format outputs table to the markup language for a document. The output is not a complete document.
null Sets a character string to be printed in place of a null value. By default, nothing is printed, which can easily be mistaken for an empty character string.
numericlocale Enables or disables the display of a locale-specific character to separate groups of digits to the left of the decimal marker. - on: The specified separator is displayed.
- off: The specified separator is not displayed.
If this parameter is ignored, the default separator is displayed.
pager Controls the use of a pager for query and gsql help outputs. If the PAGER environment variable is set, the output is piped to the specified program. Otherwise, a platform-dependent default is used. - on: The pager is used for terminal output that does not fit the screen.
- off: The pager is not used.
- always: The pager is used for all terminal output regardless of whether it fits the screen.
recordsep Specifies the record separator to be used in unaligned output format. -
recordsep_zero Specifies the record separator to be used in unaligned output format to zero bytes. -
tableattr (or T) Specifies attributes to be placed inside the HTML table tag in HTML output format (such as cellpadding or bgcolor). Note that you do not need to specify border here because it has been used by \pset border. If no value is given, the table attributes do not need to be set. -
title Specifies 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 does not need to be set. -
tuples_only (or t) Enables or disables the tuples-only mode. Full display may show extra information, such as column headers, titles, and footers. In tuples-only mode, only the table data is displayed. -
feedback Specifies whether to output the number of result lines. -

Table 8 Connection meta-commands

Parameter Description Value Range
\c[onnect] [DBNAME |- USER|- HOST|- PORT|-] Connects to a new database. The current database is postgres. If a database name contains more than 63 bytes, only the first 63 bytes are valid and are used for connection. However, the database name displayed in the command line of gsql is still the name before the truncation.
NOTE:
If the database login user is changed during reconnection, you need to enter the password for the new user. The maximum length of the password is 999 bytes, which is restricted by the maximum value of the GUC parameter password_max_length.		 -
\encoding [ENCODING] Sets the client character set encoding. This command shows the current encoding if it has no parameter.
\conninfo Outputs information about the current database connection. -

Table 9 OS meta-commands

Parameter Description Value Range
\cd [DIR] Changes the current working directory. An absolute path or relative path that meets the OS path naming convention
\setenv NAME [VALUE] Sets the NAME environment variable to VALUE. If VALUE is not provided, do not set the environment variable. -
\timing [on|off] Toggles a display of how long each SQL statement takes, in milliseconds. - on: enables the display function.
- off: disables the display function.
! [COMMAND] Escapes to a separate Unix shell or runs a Unix command. -

Table 10 Variable meta-commands

Parameter Description
\prompt [TEXT] NAME Prompts the user to use texts to specify a variable name.
\set [NAME [VALUE]] Sets the NAME internal variable to VALUE. If more than one value is provided, NAME is set to the concatenation of all of them. If only one parameter is provided, the variable is set with an empty value.
Some common variables are processed in another way in gsql, and they are the combination of uppercase letters, numbers, and underscores. Table 11 describes a list of variables that are processed in a way different from other variables.
\unset NAME Unsets or deletes the variable name of gsql.

Table 11 Common \set commands

Command Description Value Range
\set VERBOSITY value This variable can be set to default, verbose, or terse to control redundant lines of error reports. Value range: default, verbose, terse
\set ON_ERROR_STOP value If this variable is set, the script execution stops immediately. If this script is invoked from another script, that script will be stopped immediately as well. If the primary script is invoked using the -f option rather than from one gsql session, gsql will return error code 3, indicating the difference between the current error and critical errors. (The error code for critical errors is 1.) Value range: on/off, true/ false, yes/no, 1⁄0
\set RETRY [retry_times] Determines whether to enable the retry function if statement execution encounters errors. The parameter retry_times specifies the maximum number of retry times and the default value is 5. Its value ranges from 5 to 10. If the retry function has been enabled, when you run the \set RETRY command again, the retry function will be disabled.
The configuration file retry_errcodes.conf shows a list of errors. If these errors occur, retry is required. This configuration file is placed in the same directory as that for executable gsql programs. This configuration file is configured by the system rather than by users and cannot be modified by the users.
The retry function can be used in the following error scenarios:
- YY001: TCP communication errors. Print information: Connection reset by peer.
- YY002: TCP communication errors. Print information: Connection reset by peer.
- YY003: Lock timeout. Print information: Lock wait timeout…/wait transaction xxx sync time exceed xxx.
- YY004: TCP communication errors. Print information: Connection timed out.
- YY005: Failed to deliver the SET query command. Print information: ERROR SET query.
- YY006: Failed to apply for memory. Print information: memory is temporarily unavailable.
- YY007: Communication library error. Print information: Memory allocate error.
- YY008: Communication library error. Print information: No data in buffer.
- YY009: Communication library error. Print information: Close because release memory.
- YY010: Communication library error. Print information: TCP disconnect.
- YY011: Communication library error. Print information: SCTP disconnect.
- YY012: Communication library error. Print information: Stream closed by remote.
- YY013: Communication library error. Print information: Wait poll unknown error.
- YY014, YY015, 53200, 08006, 08000, 57P01, XX003, XX009
If an error occurs, gsql queries connection status of every database node. If the connection status is abnormal, gsql sleeps for 1 minute and tries again. In this case, the retries in most of the primary/standby switchover scenarios are involved.
NOTE:
1. Statements in transaction blocks cannot be retried upon a failure.
2. Retry is not supported if errors are found using ODBC or JDBC.
3. For SQL statements with unlogged tables, the retry is not supported if a node is faulty.
4. For gsql client faults, the retry is not supported.		 Value range of retry_times: 5-10

Table 12 Large object meta-commands

Parameter Description
\lo_list Displays a list of all MogDB large objects stored in the database, along with comments provided for them.

PATTERN

The various \d commands accept a PATTERN parameter to specify the object name 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, similar to those in SQL names. For example, \dt FOO will display the table named foo. As in SQL names, placing double quotation marks (") around a pattern prevents them being folded to lower case. If you need to include a double quotation mark (") in a pattern, write it as a pair of double quotation marks ("") within a double-quote sequence, which is in accordance with the rules for SQL quoted identifiers. For example, \dt "FOO""BAR" will be displayed as a table named FOO"BAR instead of foo"bar. You cannot put double quotation marks around just part of a pattern, which is different from the normal rules for SQL names. For example, \dt FOO"FOO"BAR will be displayed as a table named fooFOObar if just part of a pattern is quoted.

Whenever the PATTERN parameter is omitted completely, the \d commands display all objects that are visible in the current schema search path, which is equivalent to using an asterisk (*) as the pattern. An object is regarded to be visible if it can be referenced by name without explicit schema qualification. To see all objects in the database regardless of their visibility, use a dot within double asterisks (.) as the pattern.

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

A pattern that contains a dot (.)s interpreted as a schema name pattern followed by an object name pattern. For example, \dt foo.bar displays all tables (whose names include bar) in schemas starting with foo. If no dot appears, then the pattern matches only visible objects in the current schema search path. Again, a dot within double quotation marks loses its special meaning and is matched literally.

Advanced users can use regular-expression notations, such as character classes. For example [0-9] can be used to match any digit. All regular expression special characters, except the following, work as specified in POSIX regular expressions:

  • A dot (.) is used as a separator.
  • An asterisk (*) is translated into an asterisk prefixed with a dot (.*), which is a regular-expression marking.
  • A question mark (?) is translated into a dot (.).
  • A dollar sign ($) is matched literally.

You can, as required, write ?, (R+|), (R|), and R to the following PATTERN characters: ., R*, and R?. The dollar sign ($) does not need to work as a regular-expression character since the pattern must match the whole name, which is different from the usual interpretation of regular expressions. In other words, the dollar sign ($) is automatically appended to your pattern. If you do not expect a pattern to be anchored, write an asterisk (*) at its beginning or end. All regular-expression special characters within double quotation marks lose their special meanings and are matched literally. Regular-expression special characters in operator name patterns (such as the \do parameter) are also matched literally.

HOME

Issue
Copyright © 2011-2024 www.enmotech.com All rights reserved.