CREATE DB_DISCOVERY RULE

Description

The CREATE DB_DISCOVERY RULE syntax is used to create a database discovery rule.

Syntax

Grammar Railroad diagram

CreateDatabaseDiscoveryRule ::=
  'CREATE' 'DB_DISCOVERY' 'RULE' ifNotExists? databaseDiscoveryDefinition (',' databaseDiscoveryDefinition)*
ifNotExists ::=
  'IF' 'NOT' 'EXISTS'
databaseDiscoveryDefinition ::=
  ruleName '(' 'STORAGE_UNITS' '(' storageUnitName (',' storageUnitName)* ')' ',' 'TYPE' '(' 'NAME' '=' typeName (',' propertiesDefinition)? ')' ',' 'HEARTBEAT' '(' propertiesDefinition ')' ')' 
propertiesDefinition ::=
  'PROPERTIES' '(' key '=' value (',' key '=' value)* ')'
ruleName ::=
  identifier
storageUnitName ::=
  identifier
typeName ::=
  identifier
discoveryHeartbeatName ::=
  identifier
key ::=
  string
value ::=
  literal

Supplement

• discoveryType specifies the database discovery service type, ShardingSphere has built-in support for MySQL.MGR;
• Duplicate ruleName will not be created;
• ifNotExists clause used for avoid Duplicate db_discovery rule error.

Example

• Create database discovery rule

CREATE DB_DISCOVERY RULE db_discovery_group_0 (
    STORAGE_UNITS(ds_0, ds_1, ds_2),
    TYPE(NAME='MySQL.MGR',PROPERTIES('group-name'='92504d5b-6dec')),
    HEARTBEAT(PROPERTIES('keep-alive-cron'='0/5 * * * * ?'))
);

• Create database discovery rule with ifNotExists clause

CREATE DB_DISCOVERY RULE IF NOT EXISTS db_discovery_group_0 (
    STORAGE_UNITS(ds_0, ds_1, ds_2),
    TYPE(NAME='MySQL.MGR',PROPERTIES('group-name'='92504d5b-6dec')),
    HEARTBEAT(PROPERTIES('keep-alive-cron'='0/5 * * * * ?'))
);

Reserved word

CREATE, DB_DISCOVERY, RULE, STORAGE_UNITS, TYPE, NAME, PROPERTIES, HEARTBEAT

Related links

• Reserved word