ShardingSphere > Reference > DistSQL > Syntax > RDL Syntax > Storage Unit Definition > ALTER STORAGE UNIT

ALTER STORAGE UNIT

Description

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

Syntax

AlterResource ::=
  'ALTER' 'STORAGE' 'UNIT' storageUnitDefinition (',' storageUnitDefinition)*

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

storageUnitName ::=
  identifier

hostname ::=
  string
    
port ::=
  int

dbName ::=
  string

url ::=
  string

user ::=
  string

password ::=
  string

proerties ::=
  PROPERTIES '(' property ( ',' property )* ')'

property ::=
  key '=' value

key ::=
  string

value ::=
  string

Supplement

Before altering the storage units, please confirm that a database exists in Proxy, and execute the use command to successfully select a database;
ALTER STORAGE UNIT is not allowed to change the real data source associated with this storageUnit;
ALTER STORAGE UNIT will switch the connection pool. This operation may affect the ongoing business, please use it with caution;
storageUnitName is case-sensitive;
storageUnitName needs to be unique within the current database;
storageUnitName name only allows letters, numbers and _, and must start with a letter;
poolProperty is used to customize connection pool parameters, key must be the same as the connection pool parameter name, value supports int and String types;
When password contains special characters, it is recommended to use the string form; for example, the string form of password@123 is "password@123".

Example

Alter storage unit using standard mode

ALTER STORAGE UNIT su_0 (
    HOST=127.0.0.1,
    PORT=3306,
    DB=db_0,
    USER=root,
    PASSWORD=root
);

Alter storage unit and set connection pool parameters using standard mode

ALTER STORAGE UNIT su_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 parameters using URL patterns

ALTER STORAGE UNIT su_2 (
    URL="jdbc:mysql://127.0.0.1:3306/db_2?serverTimezone=UTC&useSSL=false",
    USER=root,
    PASSWORD=root,
    PROPERTIES("maximumPoolSize"=10,"idleTimeout"="30000")
);

Reserved word

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

Reserved word