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Fixes: #55273
654 lines
22 KiB
Markdown
654 lines
22 KiB
Markdown
---
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slug: /en/sql-reference/statements/show
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sidebar_position: 37
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sidebar_label: SHOW
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---
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# SHOW Statements
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N.B. `SHOW CREATE (TABLE|DATABASE|USER)` hides secrets unless
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[`display_secrets_in_show_and_select` server setting](../../operations/server-configuration-parameters/settings#display_secrets_in_show_and_select)
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is turned on,
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[`format_display_secrets_in_show_and_select` format setting](../../operations/settings/formats#format_display_secrets_in_show_and_select)
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is turned on and user has
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[`displaySecretsInShowAndSelect`](grant.md#grant-display-secrets) privilege.
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## SHOW CREATE TABLE | DICTIONARY | VIEW | DATABASE
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``` sql
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SHOW [CREATE] [TEMPORARY] TABLE|DICTIONARY|VIEW|DATABASE [db.]table|view [INTO OUTFILE filename] [FORMAT format]
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```
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Returns a single column of type String containing the CREATE query used for creating the specified object.
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`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.
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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.
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## SHOW DATABASES
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Prints a list of all databases.
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```sql
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SHOW DATABASES [[NOT] LIKE | ILIKE '<pattern>'] [LIMIT <N>] [INTO OUTFILE filename] [FORMAT format]
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```
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This statement is identical to the query:
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```sql
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SELECT name FROM system.databases [WHERE name [NOT] LIKE | ILIKE '<pattern>'] [LIMIT <N>] [INTO OUTFILE filename] [FORMAT format]
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```
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**Examples**
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Getting database names, containing the symbols sequence 'de' in their names:
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``` sql
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SHOW DATABASES LIKE '%de%'
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```
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Result:
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``` text
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┌─name────┐
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│ default │
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└─────────┘
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```
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Getting database names, containing symbols sequence 'de' in their names, in the case insensitive manner:
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``` sql
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SHOW DATABASES ILIKE '%DE%'
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```
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Result:
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``` text
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┌─name────┐
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│ default │
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└─────────┘
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```
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Getting database names, not containing the symbols sequence 'de' in their names:
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``` sql
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SHOW DATABASES NOT LIKE '%de%'
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```
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Result:
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``` text
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┌─name───────────────────────────┐
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│ _temporary_and_external_tables │
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│ system │
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│ test │
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│ tutorial │
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└────────────────────────────────┘
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```
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Getting the first two rows from database names:
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``` sql
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SHOW DATABASES LIMIT 2
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```
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Result:
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``` text
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┌─name───────────────────────────┐
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│ _temporary_and_external_tables │
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│ default │
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└────────────────────────────────┘
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```
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**See also**
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- [CREATE DATABASE](https://clickhouse.com/docs/en/sql-reference/statements/create/database/#query-language-create-database)
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## SHOW TABLES
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Displays a list of tables.
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```sql
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SHOW [FULL] [TEMPORARY] TABLES [{FROM | IN} <db>] [[NOT] LIKE | ILIKE '<pattern>'] [LIMIT <N>] [INTO OUTFILE <filename>] [FORMAT <format>]
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```
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If the `FROM` clause is not specified, the query returns the list of tables from the current database.
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This statement is identical to the query:
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```sql
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SELECT name FROM system.tables [WHERE name [NOT] LIKE | ILIKE '<pattern>'] [LIMIT <N>] [INTO OUTFILE <filename>] [FORMAT <format>]
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```
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**Examples**
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Getting table names, containing the symbols sequence 'user' in their names:
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``` sql
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SHOW TABLES FROM system LIKE '%user%'
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```
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Result:
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``` text
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┌─name─────────────┐
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│ user_directories │
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│ users │
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└──────────────────┘
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```
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Getting table names, containing sequence 'user' in their names, in the case insensitive manner:
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``` sql
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SHOW TABLES FROM system ILIKE '%USER%'
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```
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Result:
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``` text
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┌─name─────────────┐
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│ user_directories │
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│ users │
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└──────────────────┘
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```
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Getting table names, not containing the symbol sequence 's' in their names:
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``` sql
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SHOW TABLES FROM system NOT LIKE '%s%'
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```
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Result:
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``` text
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┌─name─────────┐
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│ metric_log │
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│ metric_log_0 │
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│ metric_log_1 │
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└──────────────┘
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```
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Getting the first two rows from table names:
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``` sql
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SHOW TABLES FROM system LIMIT 2
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```
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Result:
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``` text
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┌─name───────────────────────────┐
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│ aggregate_function_combinators │
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│ asynchronous_metric_log │
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└────────────────────────────────┘
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```
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**See also**
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- [Create Tables](https://clickhouse.com/docs/en/getting-started/tutorial/#create-tables)
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- [SHOW CREATE TABLE](https://clickhouse.com/docs/en/sql-reference/statements/show/#show-create-table)
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## SHOW COLUMNS {#show_columns}
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Displays a list of columns
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```sql
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SHOW [EXTENDED] [FULL] COLUMNS {FROM | IN} <table> [{FROM | IN} <db>] [{[NOT] {LIKE | ILIKE} '<pattern>' | WHERE <expr>}] [LIMIT <N>] [INTO
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OUTFILE <filename>] [FORMAT <format>]
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```
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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
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equivalent. If no database is specified, the query returns the list of columns from the current database.
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The optional keyword `EXTENDED` currently has no effect, it only exists for MySQL compatibility.
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The optional keyword `FULL` causes the output to include the collation, comment and privilege columns.
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The statement produces a result table with the following structure:
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- `field` - The name of the column (String)
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- `type` - The column data type. If setting `[use_mysql_types_in_show_columns](../../operations/settings/settings.md#use_mysql_types_in_show_columns) = 1` (default: 0), then the equivalent type name in MySQL is shown. (String)
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- `null` - `YES` if the column data type is Nullable, `NO` otherwise (String)
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- `key` - `PRI` if the column is part of the primary key, `SOR` if the column is part of the sorting key, empty otherwise (String)
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- `default` - Default expression of the column if it is of type `ALIAS`, `DEFAULT`, or `MATERIALIZED`, otherwise `NULL`. (Nullable(String))
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- `extra` - Additional information, currently unused (String)
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- `collation` - (only if `FULL` keyword was specified) Collation of the column, always `NULL` because ClickHouse has no per-column collations (Nullable(String))
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- `comment` - (only if `FULL` keyword was specified) Comment on the column (String)
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- `privilege` - (only if `FULL` keyword was specified) The privilege you have on this column, currently not available (String)
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**Examples**
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Getting information about all columns in table 'order' starting with 'delivery_':
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```sql
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SHOW COLUMNS FROM 'orders' LIKE 'delivery_%'
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```
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Result:
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``` text
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┌─field───────────┬─type─────┬─null─┬─key─────┬─default─┬─extra─┐
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│ delivery_date │ DateTime │ 0 │ PRI SOR │ ᴺᵁᴸᴸ │ │
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│ delivery_status │ Bool │ 0 │ │ ᴺᵁᴸᴸ │ │
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└─────────────────┴──────────┴──────┴─────────┴─────────┴───────┘
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```
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**See also**
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- [system.columns](https://clickhouse.com/docs/en/operations/system-tables/columns)
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## SHOW DICTIONARIES
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Displays a list of [Dictionaries](../../sql-reference/dictionaries/index.md).
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``` sql
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SHOW DICTIONARIES [FROM <db>] [LIKE '<pattern>'] [LIMIT <N>] [INTO OUTFILE <filename>] [FORMAT <format>]
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```
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If the `FROM` clause is not specified, the query returns the list of dictionaries from the current database.
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You can get the same results as the `SHOW DICTIONARIES` query in the following way:
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``` sql
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SELECT name FROM system.dictionaries WHERE database = <db> [AND name LIKE <pattern>] [LIMIT <N>] [INTO OUTFILE <filename>] [FORMAT <format>]
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```
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**Examples**
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The following query selects the first two rows from the list of tables in the `system` database, whose names contain `reg`.
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``` sql
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SHOW DICTIONARIES FROM db LIKE '%reg%' LIMIT 2
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```
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``` text
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┌─name─────────┐
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│ regions │
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│ region_names │
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└──────────────┘
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```
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## SHOW INDEX
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Displays a list of primary and data skipping indexes of a table.
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This statement mostly exists for compatibility with MySQL. System tables [system.tables](../../operations/system-tables/tables.md) (for
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primary keys) and [system.data_skipping_indices](../../operations/system-tables/data_skipping_indices.md) (for data skipping indices)
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provide equivalent information but in a fashion more native to ClickHouse.
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```sql
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SHOW [EXTENDED] {INDEX | INDEXES | INDICES | KEYS } {FROM | IN} <table> [{FROM | IN} <db>] [WHERE <expr>] [INTO OUTFILE <filename>] [FORMAT <format>]
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```
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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
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equivalent. If no database is specified, the query assumes the current database as database.
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The optional keyword `EXTENDED` currently has no effect, it only exists for MySQL compatibility.
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The statement produces a result table with the following structure:
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- `table` - The name of the table. (String)
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- `non_unique` - Always `1` as ClickHouse does not support uniqueness constraints. (UInt8)
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- `key_name` - The name of the index, `PRIMARY` if the index is a primary key index. (String)
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- `seq_in_index` - For a primary key index, the position of the column starting from `1`. For a data skipping index: always `1`. (UInt8)
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- `column_name` - For a primary key index, the name of the column. For a data skipping index: `''` (empty string), see field "expression". (String)
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- `collation` - The sorting of the column in the index: `A` if ascending, `D` if descending, `NULL` if unsorted. (Nullable(String))
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- `cardinality` - An estimation of the index cardinality (number of unique values in the index). Currently always 0. (UInt64)
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- `sub_part` - Always `NULL` because ClickHouse does not support index prefixes like MySQL. (Nullable(String))
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- `packed` - Always `NULL` because ClickHouse does not support packed indexes (like MySQL). (Nullable(String))
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- `null` - Currently unused
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- `index_type` - The index type, e.g. `PRIMARY`, `MINMAX`, `BLOOM_FILTER` etc. (String)
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- `comment` - Additional information about the index, currently always `''` (empty string). (String)
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- `index_comment` - `''` (empty string) because indexes in ClickHouse cannot have a `COMMENT` field (like in MySQL). (String)
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- `visible` - If the index is visible to the optimizer, always `YES`. (String)
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- `expression` - For a data skipping index, the index expression. For a primary key index: `''` (empty string). (String)
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**Examples**
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Getting information about all indexes in table 'tbl'
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```sql
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SHOW INDEX FROM 'tbl'
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```
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Result:
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``` text
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┌─table─┬─non_unique─┬─key_name─┬─seq_in_index─┬─column_name─┬─collation─┬─cardinality─┬─sub_part─┬─packed─┬─null─┬─index_type───┬─comment─┬─index_comment─┬─visible─┬─expression─┐
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│ tbl │ 1 │ blf_idx │ 1 │ 1 │ ᴺᵁᴸᴸ │ 0 │ ᴺᵁᴸᴸ │ ᴺᵁᴸᴸ │ ᴺᵁᴸᴸ │ BLOOM_FILTER │ │ │ YES │ d, b │
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│ tbl │ 1 │ mm1_idx │ 1 │ 1 │ ᴺᵁᴸᴸ │ 0 │ ᴺᵁᴸᴸ │ ᴺᵁᴸᴸ │ ᴺᵁᴸᴸ │ MINMAX │ │ │ YES │ a, c, d │
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│ tbl │ 1 │ mm2_idx │ 1 │ 1 │ ᴺᵁᴸᴸ │ 0 │ ᴺᵁᴸᴸ │ ᴺᵁᴸᴸ │ ᴺᵁᴸᴸ │ MINMAX │ │ │ YES │ c, d, e │
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│ tbl │ 1 │ PRIMARY │ 1 │ c │ A │ 0 │ ᴺᵁᴸᴸ │ ᴺᵁᴸᴸ │ ᴺᵁᴸᴸ │ PRIMARY │ │ │ YES │ │
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│ tbl │ 1 │ PRIMARY │ 2 │ a │ A │ 0 │ ᴺᵁᴸᴸ │ ᴺᵁᴸᴸ │ ᴺᵁᴸᴸ │ PRIMARY │ │ │ YES │ │
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│ tbl │ 1 │ set_idx │ 1 │ 1 │ ᴺᵁᴸᴸ │ 0 │ ᴺᵁᴸᴸ │ ᴺᵁᴸᴸ │ ᴺᵁᴸᴸ │ SET │ │ │ YES │ e │
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└───────┴────────────┴──────────┴──────────────┴─────────────┴───────────┴─────────────┴──────────┴────────┴──────┴──────────────┴─────────┴───────────────┴─────────┴────────────┘
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```
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**See also**
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- [system.tables](../../operations/system-tables/tables.md)
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- [system.data_skipping_indices](../../operations/system-tables/data_skipping_indices.md)
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## SHOW PROCESSLIST
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``` sql
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SHOW PROCESSLIST [INTO OUTFILE filename] [FORMAT format]
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```
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Outputs the content of the [system.processes](../../operations/system-tables/processes.md#system_tables-processes) table, that contains a list of queries that is being processed at the moment, excepting `SHOW PROCESSLIST` queries.
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The `SELECT * FROM system.processes` query returns data about all the current queries.
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Tip (execute in the console):
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``` bash
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$ watch -n1 "clickhouse-client --query='SHOW PROCESSLIST'"
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```
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## SHOW GRANTS
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Shows privileges for a user.
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**Syntax**
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``` sql
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SHOW GRANTS [FOR user1 [, user2 ...]]
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```
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If user is not specified, the query returns privileges for the current user.
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## SHOW CREATE USER
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Shows parameters that were used at a [user creation](../../sql-reference/statements/create/user.md).
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**Syntax**
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``` sql
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SHOW CREATE USER [name1 [, name2 ...] | CURRENT_USER]
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```
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## SHOW CREATE ROLE
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Shows parameters that were used at a [role creation](../../sql-reference/statements/create/role.md).
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**Syntax**
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``` sql
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SHOW CREATE ROLE name1 [, name2 ...]
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```
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## SHOW CREATE ROW POLICY
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Shows parameters that were used at a [row policy creation](../../sql-reference/statements/create/row-policy.md).
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**Syntax**
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``` sql
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SHOW CREATE [ROW] POLICY name ON [database1.]table1 [, [database2.]table2 ...]
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```
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## SHOW CREATE QUOTA
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Shows parameters that were used at a [quota creation](../../sql-reference/statements/create/quota.md).
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**Syntax**
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``` sql
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SHOW CREATE QUOTA [name1 [, name2 ...] | CURRENT]
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```
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## SHOW CREATE SETTINGS PROFILE
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Shows parameters that were used at a [settings profile creation](../../sql-reference/statements/create/settings-profile.md).
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**Syntax**
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``` sql
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SHOW CREATE [SETTINGS] PROFILE name1 [, name2 ...]
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```
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## SHOW USERS
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Returns a list of [user account](../../guides/sre/user-management/index.md#user-account-management) names. To view user accounts parameters, see the system table [system.users](../../operations/system-tables/users.md#system_tables-users).
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**Syntax**
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``` sql
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SHOW USERS
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```
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## SHOW ROLES
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Returns a list of [roles](../../guides/sre/user-management/index.md#role-management). To view another parameters, see system tables [system.roles](../../operations/system-tables/roles.md#system_tables-roles) and [system.role_grants](../../operations/system-tables/role-grants.md#system_tables-role_grants).
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**Syntax**
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``` sql
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SHOW [CURRENT|ENABLED] ROLES
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```
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## SHOW PROFILES
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Returns a list of [setting profiles](../../guides/sre/user-management/index.md#settings-profiles-management). To view user accounts parameters, see the system table [settings_profiles](../../operations/system-tables/settings_profiles.md#system_tables-settings_profiles).
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**Syntax**
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``` sql
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SHOW [SETTINGS] PROFILES
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```
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## SHOW POLICIES
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Returns a list of [row policies](../../guides/sre/user-management/index.md#row-policy-management) for the specified table. To view user accounts parameters, see the system table [system.row_policies](../../operations/system-tables/row_policies.md#system_tables-row_policies).
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**Syntax**
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``` sql
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SHOW [ROW] POLICIES [ON [db.]table]
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```
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## SHOW QUOTAS
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Returns a list of [quotas](../../guides/sre/user-management/index.md#quotas-management). To view quotas parameters, see the system table [system.quotas](../../operations/system-tables/quotas.md#system_tables-quotas).
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**Syntax**
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``` sql
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SHOW QUOTAS
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```
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## SHOW QUOTA
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Returns a [quota](../../operations/quotas.md) consumption for all users or for current user. To view another parameters, see system tables [system.quotas_usage](../../operations/system-tables/quotas_usage.md#system_tables-quotas_usage) and [system.quota_usage](../../operations/system-tables/quota_usage.md#system_tables-quota_usage).
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**Syntax**
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``` sql
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SHOW [CURRENT] QUOTA
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```
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## SHOW ACCESS
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Shows all [users](../../guides/sre/user-management/index.md#user-account-management), [roles](../../guides/sre/user-management/index.md#role-management), [profiles](../../guides/sre/user-management/index.md#settings-profiles-management), etc. and all their [grants](../../sql-reference/statements/grant.md#grant-privileges).
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**Syntax**
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|
``` sql
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SHOW ACCESS
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```
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## SHOW CLUSTER(s)
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Returns a list of clusters. All available clusters are listed in the [system.clusters](../../operations/system-tables/clusters.md) table.
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:::note
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`SHOW CLUSTER name` query displays the contents of system.clusters table for this cluster.
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:::
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**Syntax**
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|
``` sql
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SHOW CLUSTER '<name>'
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SHOW CLUSTERS [[NOT] LIKE|ILIKE '<pattern>'] [LIMIT <N>]
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```
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**Examples**
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|
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Query:
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``` sql
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SHOW CLUSTERS;
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```
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Result:
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```text
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┌─cluster──────────────────────────────────────┐
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│ test_cluster_two_shards │
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│ test_cluster_two_shards_internal_replication │
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│ test_cluster_two_shards_localhost │
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│ test_shard_localhost │
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│ test_shard_localhost_secure │
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│ test_unavailable_shard │
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└──────────────────────────────────────────────┘
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```
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Query:
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|
|
|
``` sql
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SHOW CLUSTERS LIKE 'test%' LIMIT 1;
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```
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Result:
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|
|
|
```text
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|
┌─cluster─────────────────┐
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│ test_cluster_two_shards │
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└─────────────────────────┘
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```
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Query:
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|
|
|
``` sql
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SHOW CLUSTER 'test_shard_localhost' FORMAT Vertical;
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|
```
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|
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Result:
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|
|
|
```text
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|
Row 1:
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|
──────
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|
cluster: test_shard_localhost
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shard_num: 1
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shard_weight: 1
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replica_num: 1
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host_name: localhost
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host_address: 127.0.0.1
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port: 9000
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|
is_local: 1
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user: default
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default_database:
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|
errors_count: 0
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|
estimated_recovery_time: 0
|
|
```
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|
|
## SHOW SETTINGS
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|
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|
Returns a list of system settings and their values. Selects data from the [system.settings](../../operations/system-tables/settings.md) table.
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|
|
|
**Syntax**
|
|
|
|
```sql
|
|
SHOW [CHANGED] SETTINGS LIKE|ILIKE <name>
|
|
```
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|
|
|
**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.
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|
|
|
When the `CHANGED` clause is used, the query returns only settings changed from their default values.
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|
|
|
**Examples**
|
|
|
|
Query with the `LIKE` clause:
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|
|
|
```sql
|
|
SHOW SETTINGS LIKE 'send_timeout';
|
|
```
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|
Result:
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|
|
|
```text
|
|
┌─name─────────┬─type────┬─value─┐
|
|
│ send_timeout │ Seconds │ 300 │
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|
└──────────────┴─────────┴───────┘
|
|
```
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|
|
|
Query with the `ILIKE` clause:
|
|
|
|
```sql
|
|
SHOW SETTINGS ILIKE '%CONNECT_timeout%'
|
|
```
|
|
|
|
Result:
|
|
|
|
```text
|
|
┌─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:
|
|
|
|
```sql
|
|
SHOW CHANGED SETTINGS ILIKE '%MEMORY%'
|
|
```
|
|
|
|
Result:
|
|
|
|
```text
|
|
┌─name─────────────┬─type───┬─value───────┐
|
|
│ max_memory_usage │ UInt64 │ 10000000000 │
|
|
└──────────────────┴────────┴─────────────┘
|
|
```
|
|
|
|
## SHOW FILESYSTEM CACHES
|
|
|
|
```sql
|
|
SHOW FILESYSTEM CACHES
|
|
```
|
|
|
|
Result:
|
|
|
|
``` text
|
|
┌─Caches────┐
|
|
│ s3_cache │
|
|
└───────────┘
|
|
```
|
|
|
|
**See Also**
|
|
|
|
- [system.settings](../../operations/system-tables/settings.md) table
|
|
|
|
## SHOW ENGINES
|
|
|
|
``` sql
|
|
SHOW ENGINES [INTO OUTFILE filename] [FORMAT format]
|
|
```
|
|
|
|
Outputs the content of the [system.table_engines](../../operations/system-tables/table_engines.md) table, that contains description of table engines supported by server and their feature support information.
|
|
|
|
**See Also**
|
|
|
|
- [system.table_engines](../../operations/system-tables/table_engines.md) table
|
|
|
|
## SHOW FUNCTIONS
|
|
|
|
``` sql
|
|
SHOW FUNCTIONS [LIKE | ILIKE '<pattern>']
|
|
```
|
|
|
|
Outputs the content of the [system.functions](../../operations/system-tables/functions.md) table.
|
|
|
|
If either `LIKE` or `ILIKE` clause is specified, the query returns a list of system functions whose names match the provided `<pattern>`.
|
|
|
|
**See Also**
|
|
- [system.functions](../../operations/system-tables/functions.md) table
|