# CREATE

Create queries make a new entity of one of the following kinds:

# CREATE DATABASE

Creates a new database.

CREATE DATABASE [IF NOT EXISTS] db_name ON CLUSTER '{cluster}'

This will create a new database with the specified name, db_name. The optional IF NOT EXISTS clause will only create the database if it does not already exist.

# CREATE TABLE

Creates a new table. This query can have various syntax forms depending on a use case.

CREATE TABLE [IF NOT EXISTS] [db.]table_name
(
    name1 [type1] [NULL|NOT NULL] [DEFAULT|MATERIALIZED|EPHEMERAL|ALIAS expr1] [compression_codec] [TTL expr1],
    name2 [type2] [NULL|NOT NULL] [DEFAULT|MATERIALIZED|EPHEMERAL|ALIAS expr2] [compression_codec] [TTL expr2],
    ...
) ENGINE = engine

Creates a table named table_name in the db database or the current database if db is not set, with the structure specified in brackets and the engine engine. The structure of the table is a list of column descriptions, secondary indexes and constraints . If primary key is supported by the engine, it will be indicated as parameter for the table engine.

A column description is name type in the simplest case. Example: RegionID UInt32.

If necessary, primary key can be specified, with one or more key expressions (see below).

# Primary Key

You can define a primary key when creating a table. Primary key can be specified in two ways:

  • Inside the column list

    CREATE TABLE db.table_name
    (
        name1 type1, name2 type2, ...,
        PRIMARY KEY(expr1[, expr2,...])
    ) ENGINE = engine;
    
  • Outside the column list

    CREATE TABLE db.table_name
    (
        name1 type1, name2 type2, ...
    ) ENGINE = engine
    PRIMARY KEY(expr1[, expr2,...]);
    

# ENGINE

The most universal and functional table engines for high-load tasks. The property shared by these engines is quick data insertion with subsequent background data processing. MergeTree family engines support data replication (with Replicated* versions of engines), partitioning, secondary data-skipping indexes, and other features not supported in other engines.

CREATE TABLE [db.]table_name
(
    id UInt32,
    name String
)
ENGINE = MergeTree

Engines in the family:

  • MergeTree
  • ReplacingMergeTree
  • SummingMergeTree
  • AggregatingMergeTree
  • CollapsingMergeTree
  • VersionedCollapsingMergeTree
  • GraphiteMergeTree

# CREATE USER

Creates user accounts.

CREATE USER [IF NOT EXISTS | OR REPLACE] name1 ON CLUSTER '{cluster}'
    [NOT IDENTIFIED | IDENTIFIED {[WITH {no_password | plaintext_password | sha256_password | sha256_hash | double_sha1_password | double_sha1_hash}] BY {'password' | 'hash'}} | {WITH ldap SERVER 'server_name'} | {WITH kerberos [REALM 'realm']} | {WITH ssl_certificate CN 'common_name'}]
    [HOST {LOCAL | NAME 'name' | REGEXP 'name_regexp' | IP 'address' | LIKE 'pattern'} [,...] | ANY | NONE]
    [IN access_storage_type]
    [DEFAULT ROLE role [,...]]
    [DEFAULT DATABASE database | NONE]
    [GRANTEES {user | role | ANY | NONE} [,...] [EXCEPT {user | role} [,...]]]
    [SETTINGS variable [= value] [MIN [=] min_value] [MAX [=] max_value] [READONLY | WRITABLE] | PROFILE 'profile_name'] [,...]

# Identification

There are multiple ways of user identification:

  • IDENTIFIED WITH no_password

  • IDENTIFIED WITH plaintext_password BY 'qwerty'

  • IDENTIFIED WITH sha256_password BY 'qwerty' or IDENTIFIED BY 'password'

  • IDENTIFIED WITH sha256_hash BY 'hash' or IDENTIFIED WITH sha256_hash BY 'hash' SALT 'salt'

  • IDENTIFIED WITH double_sha1_password BY 'qwerty'

  • IDENTIFIED WITH double_sha1_hash BY 'hash'

  • IDENTIFIED WITH bcrypt_password BY 'qwerty'

  • IDENTIFIED WITH bcrypt_hash BY 'hash'

  • IDENTIFIED WITH ldap SERVER 'server_name'

  • IDENTIFIED WITH kerberos or IDENTIFIED WITH kerberos REALM 'realm'

  • IDENTIFIED WITH ssl_certificate CN 'mysite.com:user'

  • IDENTIFIED BY 'qwerty'

# User Host

User host is a host from which a connection to ClickHouse server could be established. The host can be specified in the HOST query section in the following ways:

  • HOST IP 'ip_address_or_subnetwork' — User can connect to ClickHouse server only from the specified IP address or a subnetwork. Examples: HOST IP '192.168.0.0/16', HOST IP '2001:DB8::/32'. For use in production, only specify HOST IP elements (IP addresses and their masks), since using host and host_regexp might cause extra latency.

  • HOST ANY — User can connect from any location. This is a default option.

  • HOST LOCAL — User can connect only locally.

  • HOST NAME 'fqdn' — User host can be specified as FQDN. For example, HOST NAME 'mysite.com'.

  • HOST REGEXP 'regexp' — You can use pcre regular expressions when specifying user hosts. For example, HOST REGEXP '.*\.mysite\.com'.

  • HOST LIKE 'template' — Allows you to use the LIKE operator to filter the user hosts. For example, HOST LIKE '%' is equivalent to HOST ANY, HOST LIKE '%.mysite.com' filters all the hosts in the mysite.com domain.

Another way of specifying host is to use @ syntax following the username. Examples:

  • CREATE USER mira@'127.0.0.1' — Equivalent to the HOST IP syntax.

  • CREATE USER mira@'localhost' — Equivalent to the HOST LOCAL syntax.

  • CREATE USER mira@'192.168.%.%' — Equivalent to the HOST LIKE syntax.

# GRANTEES Clause

Specifies users or roles which are allowed to receive privileges from this user on the condition this user has also all required access granted with GRANT OPTION. Options of the GRANTEES clause:

  • user — Specifies a user this user can grant privileges to.

  • role — Specifies a role this user can grant privileges to.

  • ANY — This user can grant privileges to anyone. It's the default setting.

  • NONE — This user can grant privileges to none.

You can exclude any user or role by using the EXCEPT expression. For example, CREATE USER user1 GRANTEES ANY EXCEPT user2. It means if user1 has some privileges granted with GRANT OPTION it will be able to grant those privileges to anyone except user2.

# CREATE ROLE

Creates new roles. Role is a set of privileges (opens new window). A user assigned a role gets all the privileges of this role.

CREATE ROLE [IF NOT EXISTS | OR REPLACE] name1 ON CLUSTER '{cluster}'
    [IN access_storage_type]
    [SETTINGS variable [= value] [MIN [=] min_value] [MAX [=] max_value] [CONST|READONLY|WRITABLE|CHANGEABLE_IN_READONLY] | PROFILE 'profile_name'] [,...]

# Managing Roles

A user can be assigned multiple roles. Users can apply their assigned roles in arbitrary combinations by the SET ROLE statement. The final scope of privileges is a combined set of all the privileges of all the applied roles. If a user has privileges granted directly to it’s user account, they are also combined with the privileges granted by roles.

User can have default roles which apply at user login. To set default roles, use the SET DEFAULT ROLE statement or the ALTER USER statement.

To revoke a role, use the REVOKE (opens new window) statement.

To delete role, use the DROP ROLE statement. The deleted role is being automatically revoked from all the users and roles to which it was assigned.

  • For CREAR statements related to vectors, please refer to Vector Search.

  • By utilizing the MyScale RBAC (Role-Based Access Control) function, you can effectively manage data-sharing among multiple users. For more advanced usage related to creating users and roles, please refer to Access Control.

Last Updated: Thu Mar 14 2024 05:32:10 GMT+0000