ShardingSphere > User Manual > Common Configuration > Builtin Algorithm > Shadow Algorithm

Shadow Algorithm

Background

The shadow DB feature carries out shadow measurement to SQL statements executed. Shadow measurement supports two types of algorithms, and users can choose one or a combination of them based on actual business needs.

Parameters

Column-based shadow algorithm

Column value matching shadow algorithm

Type：VALUE_MATCH

Attribute Name	Data Type	Description
column	String	shadow column
operation	String	SQL operation type (INSERT, UPDATE, DELETE, SELECT)
value	String	value matched by shadow column

Column-based Regex matching algorithm

Type：REGEX_MATCH

Attribute Name	Data Type	Description
column	String	match a column
operation	String	SQL operation type（INSERT, UPDATE, DELETE, SELECT）
regex	String	shadow column matching Regex

Hint-based shadow algorithm

Simple Hint matching shadow algorithm

Type：SIMPLE_HINT

Attribute Name	Data Type	Description
foo	String	bar

Configuration sample

Java API

public final class ShadowConfiguration {
    // ...
    
    private AlgorithmConfiguration createShadowAlgorithmConfiguration() {
        Properties userIdInsertProps = new Properties();
        userIdInsertProps.setProperty("operation", "insert");
        userIdInsertProps.setProperty("column", "user_id");
        userIdInsertProps.setProperty("value", "1");
        return new AlgorithmConfiguration("VALUE_MATCH", userIdInsertProps));
    }
    
    // ...
}

YAML:

shadowAlgorithms:
  user-id-insert-algorithm:
    type: VALUE_MATCH
    props:
      column: user_id
      operation: insert
      value: 1

Spring Boot Starter:

spring.shardingsphere.rules.shadow.shadow-algorithms.user-id-insert-algorithm.type=VALUE_MATCH
spring.shardingsphere.rules.shadow.shadow-algorithms.user-id-insert-algorithm.props.operation=insert
spring.shardingsphere.rules.shadow.shadow-algorithms.user-id-insert-algorithm.props.column=user_id
spring.shardingsphere.rules.shadow.shadow-algorithms.user-id-insert-algorithm.props.value=1

Spring Namespace:

<shadow:shadow-algorithm id="user-id-insert-algorithm" type="VALUE_MATCH">
    <props>
        <prop key="operation">insert</prop>
        <prop key="column">user_id</prop>
        <prop key="value">1</prop>
    </props>
</shadow:shadow-algorithm>