ShardingSphere > User Manual > ShardingSphere-Proxy > DistSQL > Syntax > RDL Syntax > Rule Definition > Shadow

Shadow

Syntax

CREATE SHADOW RULE shadowRuleDefinition [, shadowRuleDefinition] ... 

ALTER SHADOW RULE shadowRuleDefinition [, shadowRuleDefinition] ... 

DROP SHADOW RULE ruleName [, ruleName] ...

DROP SHADOW ALGORITHM algorithmName [, algorithmName] ...
    
CREATE DEFAULT SHADOW ALGORITHM shadowAlgorithm

ALTER DEFAULT SHADOW ALGORITHM shadowAlgorithm

DROP DEFAULT SHADOW ALGORITHM [IF EXISTS]

SHOW DEFAULT SHADOW ALGORITHM

SHOW SHADOW ALGORITHMS

shadowRuleDefinition: ruleName(storageUnitMapping, shadowTableRule [, shadowTableRule] ...)

storageUnitMapping: SOURCE=storageUnitName, SHADOW=storageUnitName

shadowTableRule: tableName(shadowAlgorithm [, shadowAlgorithm] ...)

shadowAlgorithm: TYPE(NAME=shadowAlgorithmType, PROPERTIES([algorithmProperties] ...))

algorithmProperties: algorithmProperty [, algorithmProperty] ... 

algorithmProperty: key=value

Parameters Explained

name	DateType	Description
ruleName	IDENTIFIER	Rule name
storageUnitName	IDENTIFIER	Storage unit name
tableName	IDENTIFIER	Shadow table name
algorithmName	IDENTIFIER	Shadow algorithm name
shadowAlgorithmType	STRING	Shadow algorithm type

Notes

Duplicate ruleName cannot be created
storageUnitMapping specifies the mapping relationship between the source database and the shadow library. You need to use the storage unit managed by RDL, please refer to storage unit
shadowAlgorithmType currently supports VALUE_MATCH, REGEX_MATCH and SIMPLE_HINT
When executing ALTER SHADOW RULE, the corresponding shadowAlgorithm will not be removed
When creating shadow rule, algorithmName will be automatically generated according to ruleName, tableName, shadowAlgorithmType and algorithm collection index. The default name is default_shadow_algorithm.

Example

CREATE SHADOW RULE shadow_rule(
SOURCE=demo_ds,
SHADOW=demo_ds_shadow,
t_order(TYPE(NAME="SIMPLE_HINT", PROPERTIES("shadow"=true, "foo"="bar")),TYPE(NAME="REGEX_MATCH", PROPERTIES("operation"="insert","column"="user_id", "regex"='[1]'))), 
t_order_item(TYPE(NAME="VALUE_MATCH", PROPERTIES("operation"="insert","column"="user_id", "value"=1))));

ALTER SHADOW RULE shadow_rule(
SOURCE=demo_ds,
SHADOW=demo_ds_shadow,
t_order(TYPE(NAME="SIMPLE_HINT", PROPERTIES("shadow"=true, "foo"="bar")),TYPE(NAME="REGEX_MATCH", PROPERTIES("operation"="insert","column"="user_id", "regex"='[1]'))), 
t_order_item(TYPE(NAME="VALUE_MATCH", PROPERTIES("operation"="insert","column"="user_id", "value"=1))));

DROP SHADOW RULE shadow_rule;

DROP SHADOW ALGORITHM simple_hint_algorithm;

CREATE DEFAULT SHADOW ALGORITHM TYPE(NAME="SIMPLE_HINT", PROPERTIES("shadow"=true, "foo"="bar"));

ALTER DEFAULT SHADOW ALGORITHM TYPE(NAME="SIMPLE_HINT", PROPERTIES("shadow"=false, "foo"="bar"));

SHOW DEFAULT SHADOW ALGORITHM;

DROP DEFAULT SHADOW ALGORITHM;