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146 lines
6.8 KiB
Markdown
146 lines
6.8 KiB
Markdown
---
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slug: /en/interfaces/mysql
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sidebar_position: 20
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sidebar_label: MySQL Interface
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---
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# MySQL Interface
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ClickHouse supports the MySQL wire protocol. This allow tools that are MySQL-compatible to interact with ClickHouse seamlessly (e.g. [Looker Studio](../integrations/data-visualization/looker-studio-and-clickhouse.md)).
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## Enabling the MySQL Interface On ClickHouse Cloud
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1. After creating your ClickHouse Cloud Service, on the credentials screen, select the MySQL tab
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2. Toggle the switch to enable the MySQL interface for this specific service. This will expose port `3306` for this service and prompt you with your MySQL connection screen that include your unique MySQL username. The password will be the same as the service's default user password.
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Alternatively, in order to enable the MySQL interface for an existing service:
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1. Ensure your service is in `Running` state then click on the "View connection string" button for the service you want to enable the MySQL interface for
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2. Toggle the switch to enable the MySQL interface for this specific service. This will prompt you to enter the default password.
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3. After entering the password, you will get prompted the MySQL connection string for this service
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## Creating multiple MySQL users in ClickHouse Cloud
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By default, there is a built-in `mysql4<subdomain>` user, which uses the same password as the `default` one. The `<subdomain>` part is the first segment of your ClickHouse Cloud hostname. This format is necessary to work with the tools that implement secure connection, but don't provide [SNI information in their TLS handshake](https://www.cloudflare.com/learning/ssl/what-is-sni), which makes it impossible to do the internal routing without an extra hint in the username (MySQL console client is one of such tools).
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Because of this, we _highly recommend_ following the `mysql4<subdomain>_<username>` format when creating a new user intended to be used with the MySQL interface, where `<subdomain>` is a hint to identify your Cloud service, and `<username>` is an arbitrary suffix of your choice.
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:::tip
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For ClickHouse Cloud hostname like `foobar.us-east1.aws.clickhouse.cloud`, the `<subdomain>` part equals to `foobar`, and a custom MySQL username could look like `mysql4foobar_team1`.
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:::
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You can create extra users to use with the MySQL interface if, for example, you need to apply extra settings.
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1. Optional - create a [settings profile](https://clickhouse.com/docs/en/sql-reference/statements/create/settings-profile) to apply for your custom user. For example, `my_custom_profile` with an extra setting which will be applied by default when we connect with the user we create later:
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```sql
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CREATE SETTINGS PROFILE my_custom_profile SETTINGS prefer_column_name_to_alias=1;
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```
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`prefer_column_name_to_alias` is used just as an example, you can use other settings there.
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2. [Create a user](https://clickhouse.com/docs/en/sql-reference/statements/create/user) using the following format: `mysql4<subdomain>_<username>` ([see above](#creating-multiple-mysql-users-in-clickhouse-cloud)). The password must be in double SHA1 format. For example:
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```sql
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CREATE USER mysql4foobar_team1 IDENTIFIED WITH double_sha1_password BY 'YourPassword42$';
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```
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or if you want to use a custom profile for this user:
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```sql
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CREATE USER mysql4foobar_team1 IDENTIFIED WITH double_sha1_password BY 'YourPassword42$' SETTINGS PROFILE 'my_custom_profile';
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```
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where `my_custom_profile` is the name of the profile you created earlier.
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3. [Grant](https://clickhouse.com/docs/en/sql-reference/statements/grant) the new user the necessary permissions to interact with the desired tables or databases. For example, if you want to grant access to `system.query_log` only:
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```sql
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GRANT SELECT ON system.query_log TO mysql4foobar_team1;
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```
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4. Use the created user to connect to your ClickHouse Cloud service with the MySQL interface.
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### Troubleshooting multiple MySQL users in ClickHouse Cloud
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If you created a new MySQL user, and you see the following error while connecting via MySQL CLI client:
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```
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ERROR 2013 (HY000): Lost connection to MySQL server at 'reading authorization packet', system error: 54
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```
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In this case, ensure that the username follows the `mysql4<subdomain>_<username>` format, as described ([above](#creating-multiple-mysql-users-in-clickhouse-cloud)).
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## Enabling the MySQL Interface On Self-managed ClickHouse
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Add the [mysql_port](../operations/server-configuration-parameters/settings.md#server_configuration_parameters-mysql_port) setting to your server's configuration file. For example, you could define the port in a new XML file in your `config.d/` [folder](../operations/configuration-files):
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``` xml
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<clickhouse>
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<mysql_port>9004</mysql_port>
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</clickhouse>
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```
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Startup your ClickHouse server and look for a log message similar to the following that mentions Listening for MySQL compatibility protocol:
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```
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{} <Information> Application: Listening for MySQL compatibility protocol: 127.0.0.1:9004
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```
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## Connect MySQL to ClickHouse
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The following command demonstrates how to connect the MySQL client `mysql` to ClickHouse:
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```bash
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mysql --protocol tcp -h [hostname] -u [username] -P [port_number] [database_name]
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```
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For example:
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``` bash
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$ mysql --protocol tcp -h 127.0.0.1 -u default -P 9004 default
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```
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Output if a connection succeeded:
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``` text
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Welcome to the MySQL monitor. Commands end with ; or \g.
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Your MySQL connection id is 4
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Server version: 20.2.1.1-ClickHouse
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Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
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Oracle is a registered trademark of Oracle Corporation and/or its
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affiliates. Other names may be trademarks of their respective
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owners.
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Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
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mysql>
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```
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For compatibility with all MySQL clients, it is recommended to specify user password with [double SHA1](../operations/settings/settings-users.md#password_double_sha1_hex) in configuration file.
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If user password is specified using [SHA256](../operations/settings/settings-users.md#password_sha256_hex), some clients won’t be able to authenticate (mysqljs and old versions of command-line tool MySQL and MariaDB).
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Restrictions:
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- prepared queries are not supported
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- some data types are sent as strings
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To cancel a long query use `KILL QUERY connection_id` statement (it is replaced with `KILL QUERY WHERE query_id = connection_id` while proceeding). For example:
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``` bash
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$ mysql --protocol tcp -h mysql_server -P 9004 default -u default --password=123 -e "KILL QUERY 123456;"
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```
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