ALTER READWRITE_SPLITTING RULE

Description

The ALTER READWRITE_SPLITTING RULE syntax is used to alter a readwrite splitting rule.

Syntax

AlterReadwriteSplittingRule ::=
  'ALTER' 'READWRITE_SPLITTING' 'RULE' readwriteSplittingDefinition (',' readwriteSplittingDefinition)*

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

Supplement

Dynamic readwrite-splitting rules rely on database discovery rules;
loadBalancerType specifies the load balancing algorithm type, please refer to Load Balance Algorithm;

Example

Alter a statics readwrite splitting rule

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

Alter a dynamic readwrite splitting rule

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

Reserved word

ALTER, READWRITE_SPLITTING, RULE, WRITE_RESOURCE, READ_RESOURCES, AUTO_AWARE_RESOURCE , WRITE_DATA_SOURCE_QUERY_ENABLED, TYPE, NAME, PROPERTIES, TRUE, FALSE

Reserved word