CREATE DEFAULT SHARDING STRATEGY

Description

The CREATE DEFAULT SHARDING STRATEGY syntax is used to create a default sharding strategy

Syntax

CreateDefaultShardingStrategy ::=
  'CREATE' 'DEFAULT' 'SHARDING' ('DATABASE' | 'TABLE') 'STRATEGY' '(' shardingStrategy ')'
shardingStrategy ::=
  'TYPE' '=' strategyType ',' ( 'SHARDING_COLUMN' '=' columnName  | 'SHARDING_COLUMNS' '=' columnNames ) ',' ( 'SHARDING_ALGORITHM' '=' algorithmName | algorithmDefinition )
algorithmDefinition ::=
  'TYPE' '(' 'NAME' '=' algorithmType ( ',' 'PROPERTIES'  '(' propertyDefinition  ')' )?')'  
columnNames ::=
  columnName (',' columnName)+
columnName ::=
  identifier
algorithmName ::=
  identifier
algorithmType ::=
  string

Supplement

• When using the complex sharding algorithm, multiple sharding columns need to be specified using SHARDING_COLUMNS;
• algorithmType is the sharding algorithm type. For detailed sharding algorithm type information, please refer to Sharding Algorithm.

Example

1.Create a default sharding strategy by using an existing sharding algorithm

-- create a sharding algorithm
CREATE SHARDING ALGORITHM database_inline (
    TYPE(NAME="inline", PROPERTIES("algorithm-expression"="t_order_${order_id % 2}"))
);
-- create a default sharding database strategy
CREATE DEFAULT SHARDING DATABASE STRATEGY (
    TYPE="standard", SHARDING_COLUMN=user_id, SHARDING_ALGORITHM=database_inline
);

2.Create sharding algorithm and default sharding table strategy at the same time

-- create a default sharding table strategy
CREATE DEFAULT SHARDING TABLE STRATEGY (
    TYPE="standard", SHARDING_COLUMN=user_id, SHARDING_ALGORITHM(TYPE(NAME="inline", PROPERTIES("algorithm-expression"="t_order_${user_id % 2}")))
);

Reserved word

CREATE, DEFAULT, SHARDING, DATABASE, TABLE, STRATEGY, TYPE, SHARDING_COLUMN, SHARDING_COLUMNS, SHARDING_ALGORITHM, NAME, PROPERTIES

Related links

• Reserved word
• CREATE SHARDING ALGORITHM