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60 lines
2.1 KiB
Markdown
60 lines
2.1 KiB
Markdown
---
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toc_priority: 58
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toc_title: Permissions for Queries
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---
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# Permissions for Queries {#permissions_for_queries}
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Queries in ClickHouse can be divided into several types:
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1. Read data queries: `SELECT`, `SHOW`, `DESCRIBE`, `EXISTS`.
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2. Write data queries: `INSERT`, `OPTIMIZE`.
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3. Change settings query: `SET`, `USE`.
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4. [DDL](https://en.wikipedia.org/wiki/Data_definition_language) queries: `CREATE`, `ALTER`, `RENAME`, `ATTACH`, `DETACH`, `DROP` `TRUNCATE`.
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5. `KILL QUERY`.
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The following settings regulate user permissions by the type of query:
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- [readonly](#settings_readonly) — Restricts permissions for all types of queries except DDL queries.
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- [allow_ddl](#settings_allow_ddl) — Restricts permissions for DDL queries.
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`KILL QUERY` can be performed with any settings.
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## readonly {#settings_readonly}
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Restricts permissions for reading data, write data and change settings queries.
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See how the queries are divided into types [above](#permissions_for_queries).
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Possible values:
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- 0 — All queries are allowed.
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- 1 — Only read data queries are allowed.
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- 2 — Read data and change settings queries are allowed.
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After setting `readonly = 1`, the user can’t change `readonly` and `allow_ddl` settings in the current session.
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When using the `GET` method in the [HTTP interface](../../interfaces/http.md), `readonly = 1` is set automatically. To modify data, use the `POST` method.
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Setting `readonly = 1` prohibit the user from changing all the settings. There is a way to prohibit the user
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from changing only specific settings, for details see [constraints on settings](../../operations/settings/constraints-on-settings.md).
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Default value: 0
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## allow_ddl {#settings_allow_ddl}
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Allows or denies [DDL](https://en.wikipedia.org/wiki/Data_definition_language) queries.
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See how the queries are divided into types [above](#permissions_for_queries).
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Possible values:
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- 0 — DDL queries are not allowed.
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- 1 — DDL queries are allowed.
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You can’t execute `SET allow_ddl = 1` if `allow_ddl = 0` for the current session.
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Default value: 1
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[Original article](https://clickhouse.com/docs/en/operations/settings/permissions_for_queries/) <!--hide-->
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