ALTER STORAGE UNIT

Description

The ALTER STORAGE UNIT syntax is used to alter storage units for the currently selected logical database.

Syntax

AlterStorageUnit ::=
  'ALTER' 'STORAGE' 'UNIT' storageUnitsDefinition (',' checkPrivileges)?

storageUnitsDefinition ::=
  storageUnitDefinition (',' storageUnitDefinition)*

storageUnitDefinition ::=
  storageUnitName '(' ('HOST' '=' hostName ',' 'PORT' '=' port ',' 'DB' '=' dbName | 'URL' '=' url) ',' 'USER' '=' user (',' 'PASSWORD' '=' password)? (',' propertiesDefinition)?')'

storageUnitName ::=
  identifier

hostname ::=
  string
    
port ::=
  int

dbName ::=
  string

url ::=
  string

user ::=
  string

password ::=
  string

propertiesDefinition ::=
  'PROPERTIES' '(' key '=' value (',' key '=' value)* ')'

key ::=
  string

value ::=
  literal

checkPrivileges ::=
  'CHECK_PRIVILEGES' '=' privilegeType (',' privilegeType)*

privilegeType ::=
  identifier

Supplement

• Before altering storage units, ensure that the target logical database exists and is selected for the current connection;
• ALTER STORAGE UNIT is not allowed to change the real data source associated with this storageUnit (determined by host, port and db);
• ALTER STORAGE UNIT will switch the connection pool. This operation may affect the ongoing business, please use it with caution;
• Please confirm that the storage unit to be altered can be connected successfully, otherwise the altering will fail;
• PROPERTIES is optional, used to customize connection pool properties, key must be the same as the connection pool property name;
• CHECK_PRIVILEGES can be specified to check privileges of the storage unit user. The supported types of privilegeType are SELECT, XA, PIPELINE, and NONE. The default value is SELECT. When NONE is included in the type list, the privilege check is skipped.

Example

• Alter storage unit using HOST & PORT method

ALTER STORAGE UNIT ds_0 (
    HOST="127.0.0.1",
    PORT=3306,
    DB="db_0",
    USER="root",
    PASSWORD="root"
);

• Alter storage unit and set connection pool properties using HOST & PORT method

ALTER STORAGE UNIT ds_1 (
    HOST="127.0.0.1",
    PORT=3306,
    DB="db_1",
    USER="root",
    PASSWORD="root",
    PROPERTIES("maximumPoolSize"=10)
);

• Alter storage unit and set connection pool properties using URL method

ALTER STORAGE UNIT ds_2 (
    URL="jdbc:mysql://127.0.0.1:3306/db_2?serverTimezone=UTC&useSSL=false&allowPublicKeyRetrieval=true",
    USER="root",
    PASSWORD="root",
    PROPERTIES("maximumPoolSize"=10,"idleTimeout"=30000)
);

• Check SELECT, XA and PIPELINE privileges when altering

ALTER STORAGE UNIT ds_2 (
    URL="jdbc:mysql://127.0.0.1:3306/db_2?serverTimezone=UTC&useSSL=false&allowPublicKeyRetrieval=true",
    USER="root",
    PASSWORD="root",
    PROPERTIES("maximumPoolSize"=10,"idleTimeout"=30000)
), CHECK_PRIVILEGES=SELECT,XA,PIPELINE;

Reserved word

ALTER, STORAGE, UNIT, HOST, PORT, DB, USER, PASSWORD, PROPERTIES, URL, CHECK_PRIVILEGES

Related links

• Reserved word