ClickHouse/docs/en/sql-reference/statements/show.md
Ivan Blinkov 7170f3c534
[docs] split aggregate function and system table references (#11742)
* prefer relative links from root

* wip

* split aggregate function reference

* split system tables
2020-06-18 11:24:31 +03:00

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38 SHOW

SHOW Queries

SHOW CREATE TABLE

SHOW CREATE [TEMPORARY] [TABLE|DICTIONARY] [db.]table [INTO OUTFILE filename] [FORMAT format]

Returns a single String-type statement column, which contains a single value the CREATE query used for creating the specified object.

SHOW DATABASES

SHOW DATABASES [INTO OUTFILE filename] [FORMAT format]

Prints a list of all databases. This query is identical to SELECT name FROM system.databases [INTO OUTFILE filename] [FORMAT format].

SHOW PROCESSLIST

SHOW PROCESSLIST [INTO OUTFILE filename] [FORMAT format]

Outputs the content of the system.processes table, that contains a list of queries that is being processed at the moment, excepting SHOW PROCESSLIST queries.

The SELECT * FROM system.processes query returns data about all the current queries.

Tip (execute in the console):

$ watch -n1 "clickhouse-client --query='SHOW PROCESSLIST'"

SHOW TABLES

Displays a list of tables.

SHOW [TEMPORARY] TABLES [{FROM | IN} <db>] [LIKE '<pattern>' | WHERE expr] [LIMIT <N>] [INTO OUTFILE <filename>] [FORMAT <format>]

If the FROM clause is not specified, the query returns the list of tables from the current database.

You can get the same results as the SHOW TABLES query in the following way:

SELECT name FROM system.tables WHERE database = <db> [AND name LIKE <pattern>] [LIMIT <N>] [INTO OUTFILE <filename>] [FORMAT <format>]

Example

The following query selects the first two rows from the list of tables in the system database, whose names contain co.

SHOW TABLES FROM system LIKE '%co%' LIMIT 2
┌─name───────────────────────────┐
│ aggregate_function_combinators │
│ collations                     │
└────────────────────────────────┘

SHOW DICTIONARIES

Displays a list of external dictionaries.

SHOW DICTIONARIES [FROM <db>] [LIKE '<pattern>'] [LIMIT <N>] [INTO OUTFILE <filename>] [FORMAT <format>]

If the FROM clause is not specified, the query returns the list of dictionaries from the current database.

You can get the same results as the SHOW DICTIONARIES query in the following way:

SELECT name FROM system.dictionaries WHERE database = <db> [AND name LIKE <pattern>] [LIMIT <N>] [INTO OUTFILE <filename>] [FORMAT <format>]

Example

The following query selects the first two rows from the list of tables in the system database, whose names contain reg.

SHOW DICTIONARIES FROM db LIKE '%reg%' LIMIT 2
┌─name─────────┐
│ regions      │
│ region_names │
└──────────────┘

SHOW GRANTS

Shows privileges for a user.

Syntax

SHOW GRANTS [FOR user]

If user is not specified, the query returns privileges for the current user.

SHOW CREATE USER

Shows parameters that were used at a user creation.

SHOW CREATE USER doesnt output user passwords.

Syntax

SHOW CREATE USER [name | CURRENT_USER]

SHOW CREATE ROLE

Shows parameters that were used at a role creation.

Syntax

SHOW CREATE ROLE name

SHOW CREATE ROW POLICY

Shows parameters that were used at a row policy creation.

Syntax

SHOW CREATE [ROW] POLICY name ON [database.]table

SHOW CREATE QUOTA

Shows parameters that were used at a quota creation.

Syntax

SHOW CREATE QUOTA [name | CURRENT]

SHOW CREATE SETTINGS PROFILE

Shows parameters that were used at a settings profile creation.

Syntax

SHOW CREATE [SETTINGS] PROFILE name

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