030.PGSQL-psql元命令

元命令

http://www.postgres.cn/docs/13/app-psql.html

postgres=# \?
General
  \copyright             show PostgreSQL usage and distribution terms
  \g [FILE] or ;         execute query (and send results to file or |pipe)
  \h [NAME]              help on syntax of SQL commands, * for all commands
  \q                     quit psql

Query Buffer
  \e [FILE] [LINE]       edit the query buffer (or file) with external editor
  \ef [FUNCNAME [LINE]]  edit function definition with external editor
  \p                     show the contents of the query buffer
  \r                     reset (clear) the query buffer
  \s [FILE]              display history or save it to file
  \w FILE                write query buffer to file

Input/Output
  \copy ...              perform SQL COPY with data stream to the client host
  \echo [STRING]         write string to standard output
  \i FILE                execute commands from file
  \ir FILE               as \i, but relative to location of current script
  \o [FILE]              send all query results to file or |pipe
  \qecho [STRING]        write string to query output stream (see \o)

Informational
  (options: S = show system objects, + = additional detail)
  \d[S+]                 list tables, views, and sequences
  \d[S+]  NAME           describe table, view, sequence, or index
  \da[S]  [PATTERN]      list aggregates
  \db[+]  [PATTERN]      list tablespaces
  \dc[S+] [PATTERN]      list conversions
  \dC[+]  [PATTERN]      list casts
  \dd[S]  [PATTERN]      show object descriptions not displayed elsewhere
  \ddp    [PATTERN]      list default privileges
  \dD[S+] [PATTERN]      list domains
  \det[+] [PATTERN]      list foreign tables
  \des[+] [PATTERN]      list foreign servers
  \deu[+] [PATTERN]      list user mappings
  \dew[+] [PATTERN]      list foreign-data wrappers
  \df[antw][S+] [PATRN]  list [only agg/normal/trigger/window] functions
  \dF[+]  [PATTERN]      list text search configurations
  \dFd[+] [PATTERN]      list text search dictionaries
  \dFp[+] [PATTERN]      list text search parsers
  \dFt[+] [PATTERN]      list text search templates
  \dg[+]  [PATTERN]      list roles
  \di[S+] [PATTERN]      list indexes
  \dl                    list large objects, same as \lo_list
  \dL[S+] [PATTERN]      list procedural languages
  \dn[S+] [PATTERN]      list schemas
  \do[S]  [PATTERN]      list operators
  \dO[S+] [PATTERN]      list collations
  \dp     [PATTERN]      list table, view, and sequence access privileges
  \drds [PATRN1 [PATRN2]] list per-database role settings
  \ds[S+] [PATTERN]      list sequences
  \dt[S+] [PATTERN]      list tables
  \dT[S+] [PATTERN]      list data types
  \du[+]  [PATTERN]      list roles
  \dv[S+] [PATTERN]      list views
  \dE[S+] [PATTERN]      list foreign tables
  \dx[+]  [PATTERN]      list extensions
  \l[+]                  list all databases
  \sf[+] FUNCNAME        show a function's definition
  \z      [PATTERN]      same as \dp

Formatting
  \a                     toggle between unaligned and aligned output mode
  \C [STRING]            set table title, or unset if none
  \f [STRING]            show or set field separator for unaligned query output
  \H                     toggle HTML output mode (currently off)
  \pset NAME [VALUE]     set table output option
                         (NAME := {format|border|expanded|fieldsep|fieldsep_zero|footer|null|
                         numericlocale|recordsep|recordsep_zero|tuples_only|title|tableattr|pager})
  \t [on|off]            show only rows (currently off)
  \T [STRING]            set HTML <table> tag attributes, or unset if none
  \x [on|off|auto]       toggle expanded output (currently off)

Connection
  \c[onnect] {[DBNAME|- USER|- HOST|- PORT|-] | conninfo}
                         connect to new database (currently "postgres")
  \encoding [ENCODING]   show or set client encoding
  \password [USERNAME]   securely change the password for a user
  \conninfo              display information about current connection

Operating System
  \cd [DIR]              change the current working directory
  \setenv NAME [VALUE]   set or unset environment variable
  \timing [on|off]       toggle timing of commands (currently off)
  \! [COMMAND]           execute command in shell or start interactive shell

Variables
  \prompt [TEXT] NAME    prompt user to set internal variable
  \set [NAME [VALUE]]    set internal variable, or list all if no parameters
  \unset NAME            unset (delete) internal variable

Large Objects
  \lo_export LOBOID FILE
  \lo_import FILE [COMMENT]
  \lo_list
  \lo_unlink LOBOID      large object operations

 

元命令的本质也是向数据库发出相应的sql查询

psql连接数据库时，-E 可以获取元命令的sql代码

 

 

[postgres@s101 /]$psql -E  -h localhost -p 5432 mydb pguser
Password for user pguser:
psql (9.2.24, server 13.3)
WARNING: psql version 9.2, server version 13.0.
         Some psql features might not work.
Type "help" for help.

mydb-> \db
********* QUERY **********
SELECT spcname AS "Name",
  pg_catalog.pg_get_userbyid(spcowner) AS "Owner",
  pg_catalog.pg_tablespace_location(oid) AS "Location"
FROM pg_catalog.pg_tablespace
ORDER BY 1;
**************************

                    List of tablespaces
    Name    |  Owner   |             Location
------------+----------+-----------------------------------
 pg_default | postgres |
 pg_global  | postgres |
 tbs_mydb   | pguser   | /var/lib/pgsql/13/pg_tbs/tbs_mydb
(3 rows)

mydb-> \l
********* QUERY **********
SELECT d.datname as "Name",
       pg_catalog.pg_get_userbyid(d.datdba) as "Owner",
       pg_catalog.pg_encoding_to_char(d.encoding) as "Encoding",
       d.datcollate as "Collate",
       d.datctype as "Ctype",
       pg_catalog.array_to_string(d.datacl, E'\n') AS "Access privileges"
FROM pg_catalog.pg_database d
ORDER BY 1;
**************************

                                  List of databases
   Name    |  Owner   | Encoding |   Collate   |    Ctype    |   Access privileges
-----------+----------+----------+-------------+-------------+-----------------------
 mydb      | pguser   | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =Tc/pguser           +
           |          |          |             |             | pguser=C*T*c*/pguser
 postgres  | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |
 template0 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/postgres          +
           |          |          |             |             | postgres=CTc/postgres
 template1 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/postgres          +
           |          |          |             |             | postgres=CTc/postgres
(4 rows)

 

\h命令可以将sql命令的语法列出

 

 

mydb-> \h
Available help:
  ABORT                            CREATE FUNCTION                  DROP TABLE
  ALTER AGGREGATE                  CREATE GROUP                     DROP TABLESPACE
  ALTER COLLATION                  CREATE INDEX                     DROP TEXT SEARCH CONFIGURATION
  ALTER CONVERSION                 CREATE LANGUAGE                  DROP TEXT SEARCH DICTIONARY
  ALTER DATABASE                   CREATE OPERATOR                  DROP TEXT SEARCH PARSER
  ALTER DEFAULT PRIVILEGES         CREATE OPERATOR CLASS            DROP TEXT SEARCH TEMPLATE
  ALTER DOMAIN                     CREATE OPERATOR FAMILY           DROP TRIGGER
  ALTER EXTENSION                  CREATE ROLE                      DROP TYPE
  ALTER FOREIGN DATA WRAPPER       CREATE RULE                      DROP USER
  ALTER FOREIGN TABLE              CREATE SCHEMA                    DROP USER MAPPING
  ALTER FUNCTION                   CREATE SEQUENCE                  DROP VIEW
  ALTER GROUP                      CREATE SERVER                    END
  ALTER INDEX                      CREATE TABLE                     EXECUTE
  ALTER LANGUAGE                   CREATE TABLE AS                  EXPLAIN
  ALTER LARGE OBJECT               CREATE TABLESPACE                FETCH
  ALTER OPERATOR                   CREATE TEXT SEARCH CONFIGURATION GRANT
  ALTER OPERATOR CLASS             CREATE TEXT SEARCH DICTIONARY    INSERT
  ALTER OPERATOR FAMILY            CREATE TEXT SEARCH PARSER        LISTEN
  ALTER ROLE                       CREATE TEXT SEARCH TEMPLATE      LOAD
  ALTER SCHEMA                     CREATE TRIGGER                   LOCK
  ALTER SEQUENCE                   CREATE TYPE                      MOVE
  ALTER SERVER                     CREATE USER                      NOTIFY
  ALTER TABLE                      CREATE USER MAPPING              PREPARE
  ALTER TABLESPACE                 CREATE VIEW                      PREPARE TRANSACTION
  ALTER TEXT SEARCH CONFIGURATION  DEALLOCATE                       REASSIGN OWNED
  ALTER TEXT SEARCH DICTIONARY     DECLARE                          REINDEX
  ALTER TEXT SEARCH PARSER         DELETE                           RELEASE SAVEPOINT
  ALTER TEXT SEARCH TEMPLATE       DISCARD                          RESET
  ALTER TRIGGER                    DO                               REVOKE
  ALTER TYPE                       DROP AGGREGATE                   ROLLBACK
  ALTER USER                       DROP CAST                        ROLLBACK PREPARED
  ALTER USER MAPPING               DROP COLLATION                   ROLLBACK TO SAVEPOINT
  ALTER VIEW                       DROP CONVERSION                  SAVEPOINT
  ANALYZE                          DROP DATABASE                    SECURITY LABEL
  BEGIN                            DROP DOMAIN                      SELECT
  CHECKPOINT                       DROP EXTENSION                   SELECT INTO
  CLOSE                            DROP FOREIGN DATA WRAPPER        SET
  CLUSTER                          DROP FOREIGN TABLE               SET CONSTRAINTS
  COMMENT                          DROP FUNCTION                    SET ROLE
  COMMIT                           DROP GROUP                       SET SESSION AUTHORIZATION
  COMMIT PREPARED                  DROP INDEX                       SET TRANSACTION
  COPY                             DROP LANGUAGE                    SHOW
  CREATE AGGREGATE                 DROP OPERATOR                    START TRANSACTION
  CREATE CAST                      DROP OPERATOR CLASS              TABLE
  CREATE COLLATION                 DROP OPERATOR FAMILY             TRUNCATE
  CREATE CONVERSION                DROP OWNED                       UNLISTEN
  CREATE DATABASE                  DROP ROLE                        UPDATE
  CREATE DOMAIN                    DROP RULE                        VACUUM
  CREATE EXTENSION                 DROP SCHEMA                      VALUES
  CREATE FOREIGN DATA WRAPPER      DROP SEQUENCE                    WITH
  CREATE FOREIGN TABLE             DROP SERVER