Shadow.En - Shardingsphere

+++ title = "Shadow Algorithm" weight = 6 +++

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

SQL HINT shadow algorithm

Type：SQL_HINT

sql

/* SHARDINGSPHERE_HINT: SHADOW=true */

Configuration sample

Java API

java

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:

yaml

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