thevar1able/ClickHouse
1
0
Fork 0
mirror of https://github.com/ClickHouse/ClickHouse.git synced 2024-11-25 00:52:02 +00:00
Code Issues Packages Projects Releases Wiki Activity
51cd0f0e3c
ClickHouse/docs/en/sql-reference/statements/show.md
János Benjamin Antal 7aab5855b6 Fix links
2024-05-02 07:00:40 +00:00

717 lines
24 KiB
Markdown
Raw Blame History

---
slug: /en/sql-reference/statements/show
sidebar_position: 37
sidebar_label: SHOW
---
# SHOW Statements
N.B. `SHOW CREATE (TABLE|DATABASE|USER)` hides secrets unless
[`display_secrets_in_show_and_select` server setting](../../operations/server-configuration-parameters/settings#display_secrets_in_show_and_select)
is turned on,
[`format_display_secrets_in_show_and_select` format setting](../../operations/settings/formats#format_display_secrets_in_show_and_select)
is turned on and user has
[`displaySecretsInShowAndSelect`](grant.md#display-secrets) privilege.
## SHOW CREATE TABLE | DICTIONARY | VIEW | DATABASE
``` sql
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.
```sql
SHOW DATABASES [[NOT] LIKE | ILIKE '<pattern>'] [LIMIT <N>] [INTO OUTFILE filename] [FORMAT format]
```
This statement is identical to the query:
```sql
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:
``` sql
SHOW DATABASES LIKE '%de%'
```
Result:
``` text
┌─name────┐
│ default │
└─────────┘
```
Getting database names, containing symbols sequence 'de' in their names, in the case insensitive manner:
``` sql
SHOW DATABASES ILIKE '%DE%'
```
Result:
``` text
┌─name────┐
│ default │
└─────────┘
```
Getting database names, not containing the symbols sequence 'de' in their names:
``` sql
SHOW DATABASES NOT LIKE '%de%'
```
Result:
``` text
┌─name───────────────────────────┐
│ _temporary_and_external_tables │
│ system │
│ test │
│ tutorial │
└────────────────────────────────┘
```
Getting the first two rows from database names:
``` sql
SHOW DATABASES LIMIT 2
```
Result:
``` text
┌─name───────────────────────────┐
│ _temporary_and_external_tables │
│ default │
└────────────────────────────────┘
```
**See also**
- [CREATE DATABASE](https://clickhouse.com/docs/en/sql-reference/statements/create/database/#query-language-create-database)
## SHOW TABLES
Displays a list of tables.
```sql
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:
```sql
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:
``` sql
SHOW TABLES FROM system LIKE '%user%'
```
Result:
``` text
┌─name─────────────┐
│ user_directories │
│ users │
└──────────────────┘
```
Getting table names, containing sequence 'user' in their names, in the case insensitive manner:
``` sql
SHOW TABLES FROM system ILIKE '%USER%'
```
Result:
``` text
┌─name─────────────┐
│ user_directories │
│ users │
└──────────────────┘
```
Getting table names, not containing the symbol sequence 's' in their names:
``` sql
SHOW TABLES FROM system NOT LIKE '%s%'
```
Result:
``` text
┌─name─────────┐
│ metric_log │
│ metric_log_0 │
│ metric_log_1 │
└──────────────┘
```
Getting the first two rows from table names:
``` sql
SHOW TABLES FROM system LIMIT 2
```
Result:
``` text
┌─name───────────────────────────┐
│ aggregate_function_combinators │
│ asynchronous_metric_log │
└────────────────────────────────┘
```
**See also**
- [Create Tables](https://clickhouse.com/docs/en/getting-started/tutorial/#create-tables)
- [SHOW CREATE TABLE](https://clickhouse.com/docs/en/sql-reference/statements/show/#show-create-table)
## SHOW COLUMNS {#show_columns}
Displays a list of columns
```sql
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. If the query was made through the MySQL wire protocol, then the equivalent type name in MySQL is shown. (String)
- `null` - `YES` if the column data type is Nullable, `NO` otherwise (String)
- `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_':
```sql
SHOW COLUMNS FROM 'orders' LIKE 'delivery_%'
```
Result:
``` text
┌─field───────────┬─type─────┬─null─┬─key─────┬─default─┬─extra─┐
│ delivery_date │ DateTime │ 0 │ PRI SOR │ ᴺᵁᴸᴸ │ │
│ delivery_status │ Bool │ 0 │ │ ᴺᵁᴸᴸ │ │
└─────────────────┴──────────┴──────┴─────────┴─────────┴───────┘
```
**See also**
- [system.columns](https://clickhouse.com/docs/en/operations/system-tables/columns)
## SHOW DICTIONARIES
Displays a list of [Dictionaries](../../sql-reference/dictionaries/index.md).
``` sql
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:
``` sql
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`.
``` sql
SHOW DICTIONARIES FROM db LIKE '%reg%' LIMIT 2
```
``` text
┌─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](../../operations/system-tables/tables.md) (for
primary keys) and [system.data_skipping_indices](../../operations/system-tables/data_skipping_indices.md) (for data skipping indices)
provide equivalent information but in a fashion more native to ClickHouse.
```sql
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'
```sql
SHOW INDEX FROM 'tbl'
```
Result:
``` text
┌─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](../../operations/system-tables/tables.md)
- [system.data_skipping_indices](../../operations/system-tables/data_skipping_indices.md)
## SHOW PROCESSLIST
``` sql
SHOW PROCESSLIST [INTO OUTFILE filename] [FORMAT format]
```
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.
The `SELECT * FROM system.processes` query returns data about all the current queries.
Tip (execute in the console):
``` bash
$ watch -n1 "clickhouse-client --query='SHOW PROCESSLIST'"
```
## SHOW GRANTS
Shows privileges for a user.
**Syntax**
``` sql
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](../../sql-reference/statements/create/user.md).
**Syntax**
``` sql
SHOW CREATE USER [name1 [, name2 ...] | CURRENT_USER]
```
## SHOW CREATE ROLE
Shows parameters that were used at a [role creation](../../sql-reference/statements/create/role.md).
**Syntax**
``` sql
SHOW CREATE ROLE name1 [, name2 ...]
```
## SHOW CREATE ROW POLICY
Shows parameters that were used at a [row policy creation](../../sql-reference/statements/create/row-policy.md).
**Syntax**
``` sql
SHOW CREATE [ROW] POLICY name ON [database1.]table1 [, [database2.]table2 ...]
```
## SHOW CREATE QUOTA
Shows parameters that were used at a [quota creation](../../sql-reference/statements/create/quota.md).
**Syntax**
``` sql
SHOW CREATE QUOTA [name1 [, name2 ...] | CURRENT]
```
## SHOW CREATE SETTINGS PROFILE
Shows parameters that were used at a [settings profile creation](../../sql-reference/statements/create/settings-profile.md).
**Syntax**
``` sql
SHOW CREATE [SETTINGS] PROFILE name1 [, name2 ...]
```
## SHOW USERS
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).
**Syntax**
``` sql
SHOW USERS
```
## SHOW ROLES
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).
**Syntax**
``` sql
SHOW [CURRENT|ENABLED] ROLES
```
## SHOW PROFILES
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).
**Syntax**
``` sql
SHOW [SETTINGS] PROFILES
```
## SHOW POLICIES
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).
**Syntax**
``` sql
SHOW [ROW] POLICIES [ON [db.]table]
```
## SHOW QUOTAS
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).
**Syntax**
``` sql
SHOW QUOTAS
```
## SHOW QUOTA
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).
**Syntax**
``` sql
SHOW [CURRENT] QUOTA
```
## SHOW ACCESS
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#privileges).
**Syntax**
``` sql
SHOW ACCESS
```
## SHOW CLUSTER(S)
Returns a list of clusters. All available clusters are listed in the [system.clusters](../../operations/system-tables/clusters.md) table.
:::note
`SHOW CLUSTER name` query displays the contents of system.clusters table for this cluster.
:::
**Syntax**
``` sql
SHOW CLUSTER '<name>'
SHOW CLUSTERS [[NOT] LIKE|ILIKE '<pattern>'] [LIMIT <N>]
```
**Examples**
Query:
``` sql
SHOW CLUSTERS;
```
Result:
```text
┌─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:
``` sql
SHOW CLUSTERS LIKE 'test%' LIMIT 1;
```
Result:
```text
┌─cluster─────────────────┐
│ test_cluster_two_shards │
└─────────────────────────┘
```
Query:
``` sql
SHOW CLUSTER 'test_shard_localhost' FORMAT Vertical;
```
Result:
```text
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](../../operations/system-tables/settings.md) table.
**Syntax**
```sql
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:
```sql
SHOW SETTINGS LIKE 'send_timeout';
```
Result:
```text
┌─name─────────┬─type────┬─value─┐
│ send_timeout │ Seconds │ 300 │
└──────────────┴─────────┴───────┘
```
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 SETTING
``` sql
SHOW SETTING <name>
```
Outputs setting value for specified setting name.
**See Also**
- [system.settings](../../operations/system-tables/settings.md) table
## 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
## SHOW MERGES
Returns a list of merges. All merges are listed in the [system.merges](../../operations/system-tables/merges.md) table.
- `table` -- Table name.
- `database` -- The name of the database the table is in.
- `estimate_complete` -- The estimated time to complete (in seconds).
- `elapsed` -- The time elapsed (in seconds) since the merge started.
- `progress` -- The percentage of completed work (0-100 percent).
- `is_mutation` -- 1 if this process is a part mutation.
- `size_compressed` -- The total size of the compressed data of the merged parts.
- `memory_usage` -- Memory consumption of the merge process.
**Syntax**
``` sql
SHOW MERGES [[NOT] LIKE|ILIKE '<table_name_pattern>'] [LIMIT <N>]
```
**Examples**
Query:
``` sql
SHOW MERGES;
```
Result:
```text
┌─table──────┬─database─┬─estimate_complete─┬─elapsed─┬─progress─┬─is_mutation─┬─size_compressed─┬─memory_usage─┐
│ your_table │ default │ 0.14 │ 0.36 │ 73.01 │ 0 │ 5.40 MiB │ 10.25 MiB │
└────────────┴──────────┴───────────────────┴─────────┴──────────┴─────────────┴─────────────────┴──────────────┘
```
Query:
``` sql
SHOW MERGES LIKE 'your_t%' LIMIT 1;
```
Result:
```text
┌─table──────┬─database─┬─estimate_complete─┬─elapsed─┬─progress─┬─is_mutation─┬─size_compressed─┬─memory_usage─┐
│ your_table │ default │ 0.14 │ 0.36 │ 73.01 │ 0 │ 5.40 MiB │ 10.25 MiB │
└────────────┴──────────┴───────────────────┴─────────┴──────────┴─────────────┴─────────────────┴──────────────┘
```
Reference in New Issue View Git Blame Copy Permalink