CREATE READWRITE_SPLITTING RULE

描述

CREATE READWRITE_SPLITTING RULE 语法用于创建读写分离规则

语法定义

CreateReadwriteSplittingRule ::=
  'CREATE' 'READWRITE_SPLITTING' 'RULE' ifNotExists? readwriteSplittingDefinition (',' readwriteSplittingDefinition)*

ifNotExists ::=
  'IF' 'NOT' 'EXISTS'

readwriteSplittingDefinition ::=
  ruleName '(' (staticReadwriteSplittingDefinition | dynamicReadwriteSplittingDefinition) (',' loadBalancerDefinition)? ')'

staticReadwriteSplittingDefinition ::=
    'WRITE_STORAGE_UNIT' '=' writeStorageUnitName ',' 'READ_STORAGE_UNITS' '(' storageUnitName (',' storageUnitName)* ')'

dynamicReadwriteSplittingDefinition ::=
    'AUTO_AWARE_RESOURCE' '=' resourceName (',' 'WRITE_DATA_SOURCE_QUERY_ENABLED' '=' ('TRUE' | 'FALSE'))?

loadBalancerDefinition ::=
    'TYPE' '(' 'NAME' '=' loadBalancerType (',' propertiesDefinition)? ')'

ruleName ::=
  identifier

writeStorageUnitName ::=
  identifier

storageUnitName ::=
  identifier

resourceName ::=
  identifier
    
loadBalancerType ::=
  string

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

key ::=
  string

value ::=
  literal

补充说明

支持创建静态读写分离规则和动态读写分离规则；
动态读写分离规则依赖于数据库发现规则；
loadBalancerType 指定负载均衡算法类型，请参考负载均衡算法；
重复的 ruleName 将无法被创建；
ifNotExists 子句用于避免出现 Duplicate readwrite_splitting rule 错误。

示例

创建静态读写分离规则

CREATE READWRITE_SPLITTING RULE ms_group_0 (
    WRITE_STORAGE_UNIT=write_ds,
    READ_STORAGE_UNITS(read_ds_0,read_ds_1),
    TYPE(NAME="random")
);

创建动态读写分离规则

CREATE READWRITE_SPLITTING RULE ms_group_1 (
    AUTO_AWARE_RESOURCE=group_0,
    WRITE_DATA_SOURCE_QUERY_ENABLED=false,
    TYPE(NAME="random")
);

使用 `ifNotExists` 子句创建读写分离规则

静态读写分离规则

CREATE READWRITE_SPLITTING RULE IF NOT EXISTS ms_group_0 (
    WRITE_STORAGE_UNIT=write_ds,
    READ_STORAGE_UNITS(read_ds_0,read_ds_1),
    TYPE(NAME="random")
);

动态读写分离规则

CREATE READWRITE_SPLITTING RULE IF NOT EXISTS ms_group_1 (
    AUTO_AWARE_RESOURCE=group_0,
    WRITE_DATA_SOURCE_QUERY_ENABLED=false,
    TYPE(NAME="random")
);

保留字

CREATE、READWRITE_SPLITTING、RULE、WRITE_RESOURCE、READ_RESOURCES、AUTO_AWARE_RESOURCE、WRITE_DATA_SOURCE_QUERY_ENABLED 、TYPE、NAME、PROPERTIES、TRUE、FALSE