ClickHouse/docs/en/sql-reference/statements/show.md

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/en/sql-reference/statements/show	37	SHOW

SHOW Statements

N.B. SHOW CREATE (TABLE|DATABASE|USER) hides secrets unless display_secrets_in_show_and_select server setting is turned on, format_display_secrets_in_show_and_select format setting is turned on and user has displaySecretsInShowAndSelect privilege.

SHOW CREATE TABLE | DICTIONARY | VIEW | DATABASE

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

Returns a single column of type String containing the CREATE query used for creating the specified object.

SHOW TABLE t and SHOW DATABASE db have the same meaning as SHOW CREATE TABLE|DATABASE t|db, but SHOW t and SHOW db are not supported.

Note that if you use this statement to get CREATE query of system tables, you will get a fake query, which only declares table structure, but cannot be used to create table.

SHOW DATABASES

Prints a list of all databases.

SHOW DATABASES [[NOT] LIKE | ILIKE '<pattern>'] [LIMIT <N>] [INTO OUTFILE filename] [FORMAT format]

This statement is identical to the query:

SELECT name FROM system.databases [WHERE name [NOT] LIKE | ILIKE '<pattern>'] [LIMIT <N>] [INTO OUTFILE filename] [FORMAT format]

Examples

Getting database names, containing the symbols sequence 'de' in their names:

SHOW DATABASES LIKE '%de%'

Result:

┌─name────┐
│ default │
└─────────┘

Getting database names, containing symbols sequence 'de' in their names, in the case insensitive manner:

SHOW DATABASES ILIKE '%DE%'

Result:

┌─name────┐
│ default │
└─────────┘

Getting database names, not containing the symbols sequence 'de' in their names:

SHOW DATABASES NOT LIKE '%de%'

Result:

┌─name───────────────────────────┐
│ _temporary_and_external_tables │
│ system                         │
│ test                           │
│ tutorial                       │
└────────────────────────────────┘

Getting the first two rows from database names:

SHOW DATABASES LIMIT 2

Result:

┌─name───────────────────────────┐
│ _temporary_and_external_tables │
│ default                        │
└────────────────────────────────┘

See also

• CREATE DATABASE

SHOW TABLES

Displays a list of tables.

SHOW [FULL] [TEMPORARY] TABLES [{FROM | IN} <db>] [[NOT] LIKE | ILIKE '<pattern>'] [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.

This statement is identical to the query:

SELECT name FROM system.tables [WHERE name [NOT] LIKE | ILIKE '<pattern>'] [LIMIT <N>] [INTO OUTFILE <filename>] [FORMAT <format>]

Examples

Getting table names, containing the symbols sequence 'user' in their names:

SHOW TABLES FROM system LIKE '%user%'

Result:

┌─name─────────────┐
│ user_directories │
│ users            │
└──────────────────┘

Getting table names, containing sequence 'user' in their names, in the case insensitive manner:

SHOW TABLES FROM system ILIKE '%USER%'

Result:

┌─name─────────────┐
│ user_directories │
│ users            │
└──────────────────┘

Getting table names, not containing the symbol sequence 's' in their names:

SHOW TABLES FROM system NOT LIKE '%s%'

Result:

┌─name─────────┐
│ metric_log   │
│ metric_log_0 │
│ metric_log_1 │
└──────────────┘

Getting the first two rows from table names:

SHOW TABLES FROM system LIMIT 2

Result:

┌─name───────────────────────────┐
│ aggregate_function_combinators │
│ asynchronous_metric_log        │
└────────────────────────────────┘

See also

• Create Tables
• SHOW CREATE TABLE

SHOW COLUMNS

Displays a list of columns

SHOW [EXTENDED] [FULL] COLUMNS {FROM | IN} <table> [{FROM | IN} <db>] [{[NOT] {LIKE | ILIKE} '<pattern>' | WHERE <expr>}] [LIMIT <N>] [INTO
OUTFILE <filename>] [FORMAT <format>]

The database and table name can be specified in abbreviated form as <db>.<table>, i.e. FROM tab FROM db and FROM db.tab are equivalent. If no database is specified, the query returns the list of columns from the current database.

The optional keyword EXTENDED currently has no effect, it only exists for MySQL compatibility.

The optional keyword FULL causes the output to include the collation, comment and privilege columns.

The statement produces a result table with the following structure:

• field - The name of the column (String)
• type - The column data type (String)
• null - If the column data type is Nullable (UInt8)
• key - PRI if the column is part of the primary key, SOR if the column is part of the sorting key, empty otherwise (String)
• default - Default expression of the column if it is of type ALIAS, DEFAULT, or MATERIALIZED, otherwise NULL. (Nullable(String))
• extra - Additional information, currently unused (String)
• collation - (only if FULL keyword was specified) Collation of the column, always NULL because ClickHouse has no per-column collations (Nullable(String))
• comment - (only if FULL keyword was specified) Comment on the column (String)
• privilege - (only if FULL keyword was specified) The privilege you have on this column, currently not available (String)

Examples

Getting information about all columns in table 'order' starting with 'delivery_':

SHOW COLUMNS FROM 'orders' LIKE 'delivery_%'

Result:

┌─field───────────┬─type─────┬─null─┬─key─────┬─default─┬─extra─┐
│ delivery_date   │ DateTime │    0 │ PRI SOR │ ᴺᵁᴸᴸ    │       │
│ delivery_status │ Bool     │    0 │         │ ᴺᵁᴸᴸ    │       │
└─────────────────┴──────────┴──────┴─────────┴─────────┴───────┘

See also

• system.columns

SHOW DICTIONARIES

Displays a list of 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>]

Examples

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 INDEX

Displays a list of primary and data skipping indexes of a table.

This statement mostly exists for compatibility with MySQL. System tables system.tables (for primary keys) and system.data_skipping_indices (for data skipping indices) provide equivalent information but in a fashion more native to ClickHouse.

SHOW [EXTENDED] {INDEX | INDEXES | INDICES | KEYS } {FROM | IN} <table> [{FROM | IN} <db>] [WHERE <expr>] [INTO OUTFILE <filename>] [FORMAT <format>]

The database and table name can be specified in abbreviated form as <db>.<table>, i.e. FROM tab FROM db and FROM db.tab are equivalent. If no database is specified, the query assumes the current database as database.

The optional keyword EXTENDED currently has no effect, it only exists for MySQL compatibility.

The statement produces a result table with the following structure:

• table - The name of the table. (String)
• non_unique - Always 1 as ClickHouse does not support uniqueness constraints. (UInt8)
• key_name - The name of the index, PRIMARY if the index is a primary key index. (String)
• seq_in_index - For a primary key index, the position of the column starting from 1. For a data skipping index: always 1. (UInt8)
• column_name - For a primary key index, the name of the column. For a data skipping index: '' (empty string), see field "expression". (String)
• collation - The sorting of the column in the index: A if ascending, D if descending, NULL if unsorted. (Nullable(String))
• cardinality - An estimation of the index cardinality (number of unique values in the index). Currently always 0. (UInt64)
• sub_part - Always NULL because ClickHouse does not support index prefixes like MySQL. (Nullable(String))
• packed - Always NULL because ClickHouse does not support packed indexes (like MySQL). (Nullable(String))
• null - Currently unused
• index_type - The index type, e.g. PRIMARY, MINMAX, BLOOM_FILTER etc. (String)
• comment - Additional information about the index, currently always '' (empty string). (String)
• index_comment - '' (empty string) because indexes in ClickHouse cannot have a COMMENT field (like in MySQL). (String)
• visible - If the index is visible to the optimizer, always YES. (String)
• expression - For a data skipping index, the index expression. For a primary key index: '' (empty string). (String)

Examples

Getting information about all indexes in table 'tbl'

SHOW INDEX FROM 'tbl'

Result:

┌─table─┬─non_unique─┬─key_name─┬─seq_in_index─┬─column_name─┬─collation─┬─cardinality─┬─sub_part─┬─packed─┬─null─┬─index_type───┬─comment─┬─index_comment─┬─visible─┬─expression─┐
│ tbl   │          1 │ blf_idx  │ 1            │ 1           │ ᴺᵁᴸᴸ      │ 0           │ ᴺᵁᴸᴸ     │ ᴺᵁᴸᴸ   │ ᴺᵁᴸᴸ │ BLOOM_FILTER │         │               │ YES     │ d, b       │
│ tbl   │          1 │ mm1_idx  │ 1            │ 1           │ ᴺᵁᴸᴸ      │ 0           │ ᴺᵁᴸᴸ     │ ᴺᵁᴸᴸ   │ ᴺᵁᴸᴸ │ MINMAX       │         │               │ YES     │ a, c, d    │
│ tbl   │          1 │ mm2_idx  │ 1            │ 1           │ ᴺᵁᴸᴸ      │ 0           │ ᴺᵁᴸᴸ     │ ᴺᵁᴸᴸ   │ ᴺᵁᴸᴸ │ MINMAX       │         │               │ YES     │ c, d, e    │
│ tbl   │          1 │ PRIMARY  │ 1            │ c           │ A         │ 0           │ ᴺᵁᴸᴸ     │ ᴺᵁᴸᴸ   │ ᴺᵁᴸᴸ │ PRIMARY      │         │               │ YES     │            │
│ tbl   │          1 │ PRIMARY  │ 2            │ a           │ A         │ 0           │ ᴺᵁᴸᴸ     │ ᴺᵁᴸᴸ   │ ᴺᵁᴸᴸ │ PRIMARY      │         │               │ YES     │            │
│ tbl   │          1 │ set_idx  │ 1            │ 1           │ ᴺᵁᴸᴸ      │ 0           │ ᴺᵁᴸᴸ     │ ᴺᵁᴸᴸ   │ ᴺᵁᴸᴸ │ SET          │         │               │ YES     │ e          │
└───────┴────────────┴──────────┴──────────────┴─────────────┴───────────┴─────────────┴──────────┴────────┴──────┴──────────────┴─────────┴───────────────┴─────────┴────────────┘

See also

• system.tables
• system.data_skipping_indices

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 GRANTS

Shows privileges for a user.

Syntax

SHOW GRANTS [FOR user1 [, user2 ...]]

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.

Syntax

SHOW CREATE USER [name1 [, name2 ...] | CURRENT_USER]

SHOW CREATE ROLE

Shows parameters that were used at a role creation.

Syntax

SHOW CREATE ROLE name1 [, name2 ...]

SHOW CREATE ROW POLICY

Shows parameters that were used at a row policy creation.

Syntax

SHOW CREATE [ROW] POLICY name ON [database1.]table1 [, [database2.]table2 ...]

SHOW CREATE QUOTA

Shows parameters that were used at a quota creation.

Syntax

SHOW CREATE QUOTA [name1 [, name2 ...] | CURRENT]

SHOW CREATE SETTINGS PROFILE

Shows parameters that were used at a settings profile creation.

Syntax

SHOW CREATE [SETTINGS] PROFILE name1 [, name2 ...]

SHOW USERS

Returns a list of user account names. To view user accounts parameters, see the system table system.users.

Syntax

SHOW USERS

SHOW ROLES

Returns a list of roles. To view another parameters, see system tables system.roles and system.role_grants.

Syntax

SHOW [CURRENT|ENABLED] ROLES

SHOW PROFILES

Returns a list of setting profiles. To view user accounts parameters, see the system table settings_profiles.

Syntax

SHOW [SETTINGS] PROFILES

SHOW POLICIES

Returns a list of row policies for the specified table. To view user accounts parameters, see the system table system.row_policies.

Syntax

SHOW [ROW] POLICIES [ON [db.]table]

SHOW QUOTAS

Returns a list of quotas. To view quotas parameters, see the system table system.quotas.

Syntax

SHOW QUOTAS

SHOW QUOTA

Returns a quota consumption for all users or for current user. To view another parameters, see system tables system.quotas_usage and system.quota_usage.

Syntax

SHOW [CURRENT] QUOTA

SHOW ACCESS

Shows all users, roles, profiles, etc. and all their grants.

Syntax

SHOW ACCESS

SHOW CLUSTER(s)

Returns a list of clusters. All available clusters are listed in the system.clusters table.

:::note SHOW CLUSTER name query displays the contents of system.clusters table for this cluster. :::

Syntax

SHOW CLUSTER '<name>'
SHOW CLUSTERS [[NOT] LIKE|ILIKE '<pattern>'] [LIMIT <N>]

Examples

Query:

SHOW CLUSTERS;

Result:

┌─cluster──────────────────────────────────────┐
│ test_cluster_two_shards                      │
│ test_cluster_two_shards_internal_replication │
│ test_cluster_two_shards_localhost            │
│ test_shard_localhost                         │
│ test_shard_localhost_secure                  │
│ test_unavailable_shard                       │
└──────────────────────────────────────────────┘

Query:

SHOW CLUSTERS LIKE 'test%' LIMIT 1;

Result:

┌─cluster─────────────────┐
│ test_cluster_two_shards │
└─────────────────────────┘

Query:

SHOW CLUSTER 'test_shard_localhost' FORMAT Vertical;

Result:

Row 1:
──────
cluster:                 test_shard_localhost
shard_num:               1
shard_weight:            1
replica_num:             1
host_name:               localhost
host_address:            127.0.0.1
port:                    9000
is_local:                1
user:                    default
default_database:
errors_count:            0
estimated_recovery_time: 0

SHOW SETTINGS

Returns a list of system settings and their values. Selects data from the system.settings table.

Syntax

SHOW [CHANGED] SETTINGS LIKE|ILIKE <name>

Clauses

LIKE|ILIKE allow to specify a matching pattern for the setting name. It can contain globs such as % or _. LIKE clause is case-sensitive, ILIKE — case insensitive.

When the CHANGED clause is used, the query returns only settings changed from their default values.

Examples

Query with the LIKE clause:

SHOW SETTINGS LIKE 'send_timeout';

Result:

┌─name─────────┬─type────┬─value─┐
│ send_timeout │ Seconds │ 300   │
└──────────────┴─────────┴───────┘

Query with the ILIKE clause:

SHOW SETTINGS ILIKE '%CONNECT_timeout%'

Result:

┌─name────────────────────────────────────┬─type─────────┬─value─┐
│ connect_timeout                         │ Seconds      │ 10    │
│ connect_timeout_with_failover_ms        │ Milliseconds │ 50    │
│ connect_timeout_with_failover_secure_ms │ Milliseconds │ 100   │
└─────────────────────────────────────────┴──────────────┴───────┘

Query with the CHANGED clause:

SHOW CHANGED SETTINGS ILIKE '%MEMORY%'

Result:

┌─name─────────────┬─type───┬─value───────┐
│ max_memory_usage │ UInt64 │ 10000000000 │
└──────────────────┴────────┴─────────────┘

SHOW FILESYSTEM CACHES

SHOW FILESYSTEM CACHES

Result:

┌─Caches────┐
│ s3_cache  │
└───────────┘

See Also

• system.settings table

SHOW ENGINES

SHOW ENGINES [INTO OUTFILE filename] [FORMAT format]

Outputs the content of the system.table_engines table, that contains description of table engines supported by server and their feature support information.

See Also

• system.table_engines table