Non-Historized Link Properties

Non-Historized Links (NHLs) are a variation of standard Links in Data Vault. They are used to model relationships or events where the history of the relationship itself is not tracked in the same way as descriptive data in Satellites. Instead, NHLs typically store the current state of a relationship or event attributes directly within the Link table.

Non-Historized Link Properties Overview

Property Name	Type	Description
`name`	`String`	The unique name for the Non-Historized Link object. This name will be used for the generated table. Example: `'USER_SESSION_EVENT'`
`entity_type`	`String`	Must be set to `'non_historized_link'` to define this object as a Non-Historized Link.
`enable_refresh`	Boolean	if `true`, non-historized link receives new data. Set to `false` if the source contains not-changing (historical) data. See Shared Properties.
`connected_hubs`	`List of Key-Value pairs`	Defines the list of Hubs that this NHL connects, specifying the relationship between them. Each item maps an alias to a Hub name. See Connected Hubs in Regular Links.
`entity_source`	`Map`	Defines the single source that feed data into this NHL. See Entity Sources Definition.
`non_historized_columns`	`List of Strings`	A list of column names that will be included directly in the NHL table to store non-historized attributes of the relationship or event.
`historized_columns`	`List of Strings`	A list of column names that, while part of the NHL's definition, are typically related to load metadata or event timestamps rather than descriptive attributes.

Non-Historized Link Specific Property Details

`non_historized_columns`

Type: List of Strings
Description: This property lists the names of the columns that will be created directly in the Non-Historized Link table to store attributes that describe the event or relationship. These columns are NOT included in the hash difference calculation.

`historized_columns`

Type: List of Strings
Description: This property lists the names of the columns that will be created directly in the Non-Historized Link table to store attributes that describe the event or relationship. These columns are included in the hash difference calculation.

`connected_hubs`

Type: List of Key-Value pairs
Description: This property defines the hubs a non-historized link connects, specified as a list of key-value pairs.
- Key: Represents the hub's alias, or the specific name of the relationship. This is necessary because a link can connect to the same hub multiple times, requiring unique aliases to distinguish each connection. The hub alias must be unique within the connected_hubs list.
- Value: Represents the actual name of the hub, which must refer to an existing hub definition.

Example: Link connecting to each hub exactly once

connected_hubs:
  - HUB_CUSTOMER: 'HUB_CUSTOMER' # <HUB ALIAS>: <HUB NAME>
  - HUB_MATERIAL: 'HUB_MATERIAL' 

Example: Link connecting to one hub multiple times

connected_hubs:
- HUB_CUSTOMER_BILL_TO: 'HUB_CUSTOMER' 
- HUB_CUSTOMER_DELIVER_TO: 'HUB_CUSTOMER' 
- HUB_MATERIAL: 'HUB_MATERIAL' 

In this scenario, unique aliases (HUB_CUSTOMER_BILL_TO, HUB_CUSTOMER_DELIVER_TO) are used to distinguish different types of customer relationships, even though they all point to the HUB_CUSTOMER hub.

Example

This example defines a Non-Historized Link (NHL) named EVENT that connects HUB_EVENT and HUB_USER. It captures event details from a source table CLICK_EVENTS, including non-historized attributes like EVENT_ID and USER_ID, and historized columns for metadata and event timestamps.

basic_non_historized_link.yaml
name: 'EVENT'
entity_type: 'non_historized_link'
enable_refresh: true
connected_hubs:
- HUB_EVENT: 'HUB_EVENT'
- HUB_USER: 'HUB_USER'

entity_source:
  urn:s2v:link_source:src_1:
    entity_source: '(SOURCE_DATA, CLICK_EVENTS)'
    source_filter: ''
    use_source_cdc_flag: true
    source_system_configuration_urn: 'urn:s2v:source_setting:yaml_interface'
    connected_hub_relations:
    - HUB_EVENT:
        business_key_mapping:
        - EVENT_BK:
          - 'EVENT_ID'
        source_business_key: ''
    - HUB_USER:
        business_key_mapping:
        - USER_BK:
          - 'USER_ID'
        source_business_key: ''

non_historized_columns: 
  - 'EVENT_ID'
  - 'USER_ID'

historized_columns:
  - 'CDC_TIMESTAMP'
  - 'EVENT_TIMESTAMP'
  - 'DESTINATION'

info

Don't forget to ensure that the business key name defined in the business_key_mapping matches the business key name used in the Hub it connects (HUB_EVENT has the business key EVENT_BK and HUB_USER has the business key USER_BK).