--- title: Link description: A Link stores each combination of business keys that a source delivers for its Hubs once, with its hash key Link_HK, in a table of the Raw Vault layer. --- [Skip to content](https://knowledge.bigenius-x.com/create-a-link#main-content) [Contact us](https://knowledge.bigenius-x.com/kb-tickets/new?hsLang=en) [Go to Customer Portal](https://knowledge.bigenius-x.com/customer-portal?hsLang=en) [![TRI\_Logo\_biGENIUS\_2020\_RGB\_s](https://knowledge.bigenius-x.com/hs-fs/hubfs/Marketing/TRI_Logo_biGENIUS_2020_RGB_s.png?width=150&height=42&name=TRI_Logo_biGENIUS_2020_RGB_s.png)](https://www.bigenius-x.com/) Open main navigation Close main navigation - [Contact us](https://knowledge.bigenius-x.com/kb-tickets/new) - [Go to Customer Portal](https://knowledge.bigenius-x.com/customer-portal) How can we help you? - There are no suggestions because the search field is empty. 1. [biGENIUS-X Knowledge Base](https://knowledge.bigenius-x.com/?hsLang=en) 2. [Generators](https://knowledge.bigenius-x.com/generators?hsLang=en) 3. [Model Object Type](https://knowledge.bigenius-x.com/generators?hsLang=en#model-object-type) # Link **Applies to** Platform: Microsoft SQL Server · Snowflake · Snowflake dbt · Databricks · Databricks dbt · Fabric Lakehouse · Fabric Warehouse · Oracle Architecture: Data Vault A Link stores each combination of business keys that a source delivers for its Hubs once, with its hash key `Link_HK`, in a table of the Raw Vault layer. Use it for a relationship or transaction between business objects, such as a loyalty card that belongs to a customer. After each load, the result view shows one row per key combination and the load that first delivered it. For special cases, use the [Driving Key Link](https://knowledge.bigenius-x.com/create-a-driving-key-link?hsLang=en), [Hierarchical Link](https://knowledge.bigenius-x.com/create-a-hierachical-link?hsLang=en) or [Same As Link](https://knowledge.bigenius-x.com/create-a-same-as-link?hsLang=en). ### Sources and relationships A Link reads [Stages](https://knowledge.bigenius-x.com/create-a-stage?hsLang=en), [RawVault Composites](https://knowledge.bigenius-x.com/create-a-raw-vault-composite?hsLang=en) and [Store Entities](https://knowledge.bigenius-x.com/create-a-store-entity?hsLang=en) of a linked Data Store project, in one or more dataflows. It has one or more relationships to [Hubs](https://knowledge.bigenius-x.com/create-a-hub?hsLang=en). The foreign-key terms of the relationships are the business keys of the Link. With one relationship, `Link_HK` equals the key of the Hub row. Link Satellites, Non-Historized Link Satellites, Record Tracking Link Satellites, Effectivity Link Satellites reference a Link. PIT, Current View, History View, BusinessVault Composite, [Vault Out](https://knowledge.bigenius-x.com/create-a-vault-out?hsLang=en) and the Business Vault types can read it as a source. ### Create a Link - With the wizard: open the menu of a Stage, RawVault Composite or Store Entity, choose **Automate** and then **Create Link**. Its steps are [Create Model Object](https://knowledge.bigenius-x.com/wizard-step-create-model-object?hsLang=en), [Create Dataflow](https://knowledge.bigenius-x.com/wizard-step-create-dataflow?hsLang=en), [Create Multiple Relations](https://knowledge.bigenius-x.com/wizard-step-create-multiple-relations?hsLang=en), [Define Roles](https://knowledge.bigenius-x.com/wizard-step-create-relations-with-role?hsLang=en), [Map Foreign Key Terms](https://knowledge.bigenius-x.com/wizard-step-map-foreign-key-terms?hsLang=en) and [Add to View](https://knowledge.bigenius-x.com/wizard-step-add-to-view?hsLang=en). See [Create a Model Object with the wizard](https://knowledge.bigenius-x.com/create-a-model-object-with-the-wizard?hsLang=en). - Manually: [create a model object](https://knowledge.bigenius-x.com/create-a-model-object?hsLang=en) of type Link in the Raw Vault layer, [add a relationship](https://knowledge.bigenius-x.com/add-a-relationship?hsLang=en) to each Hub, [create a dataflow set](https://knowledge.bigenius-x.com/create-a-data-flow-set?hsLang=en), [add the source model object](https://knowledge.bigenius-x.com/add-a-model-object-into-a-data-flow-set?hsLang=en) and [map the foreign-key terms](https://knowledge.bigenius-x.com/map-a-source-term-with-a-target-term?hsLang=en). A Link holds only foreign-key terms and Default Terms. Validation reports an error for any other term; descriptive data goes into a Link Satellite. ### Properties - [Implementation Type](https://knowledge.bigenius-x.com/implementation-type-model-object?hsLang=en): `Permanent` only. - [Foreign Key Mode](https://knowledge.bigenius-x.com/foreign-key-mode-model-object?hsLang=en): whether the table gets foreign keys to the Hub tables. With `Create Disabled`, the default, they are created and disabled. - [Load Caching](https://knowledge.bigenius-x.com/load-caching-model-object?hsLang=en): empty (default) or `Hashing`, which stores the hashing view in a table before the loader runs. - [Custom Singleton Values](https://knowledge.bigenius-x.com/custom-singleton-values-model-object?hsLang=en): values of the unknown-member row. - [Deduplication Method](https://knowledge.bigenius-x.com/deduplication-method-model-object?hsLang=en) and [Sort Order within Partition](https://knowledge.bigenius-x.com/deduplication-partition-model-object?hsLang=en), per dataflow. - [Use Embryo Loader](https://knowledge.bigenius-x.com/embryo-loader?hsLang=en), per relationship: inserts business keys that the Hub does not hold yet. ### Default Terms - [`Link_HK`](https://knowledge.bigenius-x.com/link_hk?hsLang=en): hash of the business keys of all relationships and primary key of the table. See [How biGENIUS-X builds hash values](https://knowledge.bigenius-x.com/how-bigenius-x-builds-hash-values?hsLang=en). - [`DVLINK_ForeignKey_Identity`](https://knowledge.bigenius-x.com/dvlink_foreignkey_identity?hsLang=en): names one hash-key column per relationship, `__HK`. It holds the `Hub_HK` of the related Hub row. Without a role, the Hub name takes the place of the role. - [`BG_LoadTimestamp`](https://knowledge.bigenius-x.com/bg_loadtimestamp?hsLang=en): the load that inserted the row. - [`BG_SourceSystem`](https://knowledge.bigenius-x.com/bg_sourcesystem?hsLang=en): the source system of the row; empty unless you map it. - [`BG_DataQuality_ID`](https://knowledge.bigenius-x.com/bg-dataquality-id?hsLang=en), [`BG_ErrorCount`](https://knowledge.bigenius-x.com/bg_errorcount?hsLang=en) and [`BG_ErrorDescription`](https://knowledge.bigenius-x.com/bg_errordescription?hsLang=en): hidden terms of the data quality objects. When all foreign-key terms of a nullable relationship are NULL, the Link stores the key of the Hub's unknown-member row. See [Behaviour for Nulled Business Keys in Links](https://knowledge.bigenius-x.com/behaviour-for-nulled-business-keys-in-links?hsLang=en). ### Generated objects These are the names on Microsoft SQL Server for the Link `multi_hub_lnk` with one dataflow: | Role | Generated name | Purpose | | --- | --- | --- | | Source | `RDV_LNK_multi_hub_lnk_Source` | Reads the sources | | Deduplication | `RDV_LNK_multi_hub_lnk_Deduplication` | Removes duplicate rows | | Hashing | `RDV_LNK_multi_hub_lnk_Hashing` | Calculates the hash keys | | HashingStorage | `RDV_LNK_multi_hub_lnk_HashingTable` | Stores the hashed rows | | HashingLoader | `RDV_LNK_multi_hub_lnk_HashingLoader` | Fills the hashing table | | EmbryoLoader | `RDV_LNK_multi_hub_lnk_EmbryoLoader` | Adds missing Hub keys | | Delta | `RDV_LNK_multi_hub_lnk_Delta` | Selects new key combinations | | Loader | `RDV_LNK_multi_hub_lnk_Loader` | Inserts the new rows | | Storage | `RDV_LNK_multi_hub_lnk` | Link table | | Result | `RDV_LNK_multi_hub_lnk_Result` | Query view | - Loaders are stored procedures; the Link table and the hashing table are tables; all other objects are views. - The deduplication view exists only with a Deduplication Method other than `None`. - The hashing table and hashing loader exist only with Load Caching `Hashing`. The delta view then reads the hashing table. - The embryo loader exists only when Use Embryo Loader is true on a relationship. It runs before the loader. - With several dataflows, all objects except the table and the result view exist once per dataflow, with the dataflow name in their names. - The table script inserts the unknown-member row with a `Link_HK` of zeros, Hub keys of zeros and foreign keys `0`. The result view hides it. - With Foreign Key Mode `Create Disabled`, the table script adds a foreign key per relationship to the Hub table and disables it with `NOCHECK`. - The result view always exists, independent of [Create Result Views](https://knowledge.bigenius-x.com/create-result-views-project?hsLang=en). With the default settings, a load runs this chain: ``` sources -> _Source -> _Hashing -> _Delta -> _Loader _Loader -> RDV_LNK_multi_hub_lnk -> _Result _Result -> _Delta (key combinations already stored) ``` The hashing view calculates `Link_HK` and one Hub key per relationship. The delta view keeps the rows whose `Link_HK` is not in the result view, and the loader inserts them with the load timestamp. A Link loader never updates or deletes rows, so a combination that the source no longer delivers stays in the Link. With the optional objects, `_Deduplication` sits between `_Source` and `_Hashing`, `_HashingLoader` fills `_HashingTable` before the delta view reads it, and `_EmbryoLoader` reads `_Hashing` and writes to the Hub tables. ### Example The Link `multi_hub_lnk` on Microsoft SQL Server reads the Stage `LOYALTYCARD`. It has a relationship to the Hub `common_customer` and one to the Hub `common_loyaltycard`, both without a role. Its dataflow uses Deduplication Method `Partition`. The loads deliver these cards: - Load 1 on 2026-10-28 08:00: card 501 of customer 1 and card 502 of customer 2. - Load 2 on 2026-10-29 08:00: the same cards and card 503 of customer 3. - Load 3 on 2026-10-30 08:00: the same cards as load 2. ### Check the result Query the result view, here in the schema `rv`: ``` SELECT FK_common_customer_CUSTOMER_ID AS CUSTOMER_ID, FK_common_loyaltycard_LOYALTYCARD_ID AS LOYALTYCARD_ID, Link_HK, common_customer_common_customer_HK AS customer_HK, BG_LoadTimestamp FROM rv.RDV_LNK_multi_hub_lnk_Result ORDER BY CUSTOMER_ID; ``` This is the result after load 3, with hash keys shortened to their first four bytes: ``` CUSTOMER_ID LOYALTYCARD_ID Link_HK customer_HK BG_LoadTimestamp 1 501 0xD9519207 0xE91FE173 2026-10-28 08:00 2 502 0x9A132E91 0x21ED4C7A 2026-10-28 08:00 3 503 0xC506EBFB 0x2064F80F 2026-10-29 08:00 ``` - Load 2 inserted only the combination of card 503 and customer 3. Load 3 inserted no row. - `customer_HK` is the Hub key of the customer, for example 0xE91FE173 for customer 1. A Hub of customers stores the same value. ### Platform differences - Snowflake: names are in capitals, and the loader is a stored procedure. The load control task `LC_RDV_LNK__TASK` calls it; the embryo loader has the task `LC_RDV_LNK__EMBRYOTASK`. The dataflow properties [Use Stream](https://knowledge.bigenius-x.com/use-stream-model-object?hsLang=en) and [Warehouse Placeholder Variable Name](https://knowledge.bigenius-x.com/warehouse-placeholder-variable-name-dataflow?hsLang=en) apply. - Databricks and Fabric Lakehouse: table and view names are in lowercase, and the loader is the notebook `RDV_LNK__Loader`. The properties [File Format](https://knowledge.bigenius-x.com/file-format-model-object?hsLang=en), [Optimization Method](https://knowledge.bigenius-x.com/optimization-method-model-object?hsLang=en), [Optimization Method Columns](https://knowledge.bigenius-x.com/optimization-method-columns-model-object?hsLang=en) and [Use Sequential Dataflow Execution](https://knowledge.bigenius-x.com/use-sequential-dataflow-execution-model-object?hsLang=en) apply. Fabric Lakehouse allows only Foreign Key Mode `None`. - Databricks dbt and Snowflake dbt: the Link becomes the dbt models `rdv_lnk__source` and `rdv_lnk_`. The model `rdv_lnk__result` exists only when Create Result Views is true; the default on dbt is false. Load Caching and Use Embryo Loader are not available. - Fabric Warehouse: the same objects as on Microsoft SQL Server, deployed by notebooks. - Oracle: names are in capitals, and the loader is a PL/SQL package. [Partition Clause](https://knowledge.bigenius-x.com/partition-clause-and-table-storage-model-object?hsLang=en) adds its text to the `CREATE TABLE` statement. Table Compression, the tablespaces and the statistics properties also apply. - Foreign Key Mode `Create Enforced` exists only on Microsoft SQL Server and Oracle. ### Limitations - A Link has at least one relationship and at least one business key, and no terms other than foreign keys and Default Terms. - A Link keeps no history and no validity. Link Satellites store the descriptive data and its history. - A dataflow that delivers the same key combination twice in one load makes the loader fail with a primary key violation. A Deduplication Method removes such duplicates before hashing. ### Release differences - Generator 2.2: Use Embryo Loader is available. - Generator 2.3: Custom Singleton Values is available. ### Related articles - Previous: [Hub](https://knowledge.bigenius-x.com/create-a-hub?hsLang=en) - Next: [Link Satellite](https://knowledge.bigenius-x.com/create-a-link-satellite?hsLang=en), [Non-Historized Link Satellite](https://knowledge.bigenius-x.com/create-a-non-historized-link-satellite?hsLang=en), [Record Tracking Link Satellite](https://knowledge.bigenius-x.com/create-a-record-tracking-link-satellite?hsLang=en), [Effectivity Link Satellite](https://knowledge.bigenius-x.com/create-an-effectivity-link-satellite?hsLang=en) - Reference: [Link\_HK](https://knowledge.bigenius-x.com/link_hk?hsLang=en), [DVLINK\_ForeignKey\_Identity](https://knowledge.bigenius-x.com/dvlink_foreignkey_identity?hsLang=en), [Foreign Key Mode (Model Object)](https://knowledge.bigenius-x.com/foreign-key-mode-model-object?hsLang=en), [Load Caching (Model Object)](https://knowledge.bigenius-x.com/load-caching-model-object?hsLang=en), [Custom Singleton Values (Model Object)](https://knowledge.bigenius-x.com/custom-singleton-values-model-object?hsLang=en), [Behaviour for Nulled Business Keys in Links (Project)](https://knowledge.bigenius-x.com/behaviour-for-nulled-business-keys-in-links?hsLang=en), [Create Result Views (Project)](https://knowledge.bigenius-x.com/create-result-views-project?hsLang=en) - See also: [Embryo Loader](https://knowledge.bigenius-x.com/embryo-loader?hsLang=en), [How biGENIUS-X builds hash values](https://knowledge.bigenius-x.com/how-bigenius-x-builds-hash-values?hsLang=en), [Create a Model Object with the wizard](https://knowledge.bigenius-x.com/create-a-model-object-with-the-wizard?hsLang=en), [Model a Data Vault Solution](https://knowledge.bigenius-x.com/model-a-data-vault-solution?hsLang=en) - [Getting started](https://knowledge.bigenius-x.com/getting-started?hsLang=en#main-content) - [Guidelines](https://knowledge.bigenius-x.com/getting-started?hsLang=en#guidelines) - [Start working](https://knowledge.bigenius-x.com/getting-started?hsLang=en#start-working) - [Account](https://knowledge.bigenius-x.com/getting-started?hsLang=en#account) - [General overview](https://knowledge.bigenius-x.com/general-overview?hsLang=en) - [Artificial Intelligence](https://knowledge.bigenius-x.com/artificial-intelligence?hsLang=en) - [Application Modules](https://knowledge.bigenius-x.com/application-modules?hsLang=en#main-content) - [Administration](https://knowledge.bigenius-x.com/application-modules?hsLang=en#administration) - [Solutions](https://knowledge.bigenius-x.com/application-modules?hsLang=en#solutions) - [Global Features](https://knowledge.bigenius-x.com/application-modules?hsLang=en#global-features) - [Projects](https://knowledge.bigenius-x.com/application-modules?hsLang=en#projects) - [Branches](https://knowledge.bigenius-x.com/application-modules?hsLang=en#branches) - [Data Connections](https://knowledge.bigenius-x.com/application-modules?hsLang=en#data-connections) - [Dataflow Modeling - Overview](https://knowledge.bigenius-x.com/application-modules?hsLang=en#dataflow-modeling-overview) - [Dataflow Modeling - Wizard Steps](https://knowledge.bigenius-x.com/application-modules?hsLang=en#dataflow-modeling-wizard-steps) - [Dataflow Modeling - Terms](https://knowledge.bigenius-x.com/application-modules?hsLang=en#dataflow-modeling-terms) - [Dataflow Modeling - Term Mapping](https://knowledge.bigenius-x.com/application-modules?hsLang=en#dataflow-modeling-term-mapping) - [Dataflow Modeling - Relationships](https://knowledge.bigenius-x.com/application-modules?hsLang=en#dataflow-modeling-relationships) - [Dataflow Modeling - Data Quality](https://knowledge.bigenius-x.com/application-modules?hsLang=en#dataflow-modeling-data-quality) - [Dataflow Modeling - Indexes](https://knowledge.bigenius-x.com/application-modules?hsLang=en#dataflow-modeling-indexes) - [Relationship Modeling](https://knowledge.bigenius-x.com/application-modules?hsLang=en#relationship-modeling) - [Generate Artifacts](https://knowledge.bigenius-x.com/application-modules?hsLang=en#generate-artifacts) - [Project Settings](https://knowledge.bigenius-x.com/application-modules?hsLang=en#project-settings) - [Data Marketplace](https://knowledge.bigenius-x.com/application-modules?hsLang=en#data-marketplace) - [Generators](https://knowledge.bigenius-x.com/generators?hsLang=en#main-content) - [Fabric Warehouse](https://knowledge.bigenius-x.com/generators?hsLang=en#fabric-warehouse) - [Fabric Lakehouse](https://knowledge.bigenius-x.com/generators?hsLang=en#fabric-lakehouse) - [Databricks](https://knowledge.bigenius-x.com/generators?hsLang=en#databricks) - [Snowflake](https://knowledge.bigenius-x.com/generators?hsLang=en#snowflake) - [Microsoft SQL Server](https://knowledge.bigenius-x.com/generators?hsLang=en#microsoft-sql-server) - [Oracle](https://knowledge.bigenius-x.com/generators?hsLang=en#oracle) - [Artifacts](https://knowledge.bigenius-x.com/generators?hsLang=en#artifacts) - [Replace Placeholders](https://knowledge.bigenius-x.com/generators?hsLang=en#replace-placeholders) - [Target solution environment](https://knowledge.bigenius-x.com/generators?hsLang=en#target-solution-environment) - [Deployment](https://knowledge.bigenius-x.com/generators?hsLang=en#deployment) - [Deployment with an Azuze DevOps pipeline](https://knowledge.bigenius-x.com/generators?hsLang=en#deployment-with-an-azuze-devops-pipeline) - [Delta Deployment](https://knowledge.bigenius-x.com/generators?hsLang=en#delta-deployment) - [Load control environment](https://knowledge.bigenius-x.com/generators?hsLang=en#load-control-environment) - [Load data with a native load control](https://knowledge.bigenius-x.com/generators?hsLang=en#load-data-with-a-native-load-control) - [Load data with Apache Airflow](https://knowledge.bigenius-x.com/generators?hsLang=en#load-data-with-apache-airflow) - [Model Object Type](https://knowledge.bigenius-x.com/generators?hsLang=en#model-object-type) - [Properties](https://knowledge.bigenius-x.com/generators?hsLang=en#properties) - [Default Terms](https://knowledge.bigenius-x.com/generators?hsLang=en#default-terms) - [Discovery application](https://knowledge.bigenius-x.com/discovery-application?hsLang=en#main-content) - [Discovery configurations](https://knowledge.bigenius-x.com/discovery-application?hsLang=en#discovery-configurations) - [Best practices](https://knowledge.bigenius-x.com/best-practices?hsLang=en#main-content) - [Modeling Approaches](https://knowledge.bigenius-x.com/best-practices?hsLang=en#modeling-approaches) - [Use Cases](https://knowledge.bigenius-x.com/best-practices?hsLang=en#use-cases) - [Business Rules](https://knowledge.bigenius-x.com/best-practices?hsLang=en#business-rules) - [Data Quality Rules](https://knowledge.bigenius-x.com/best-practices?hsLang=en#data-quality-rules) - [FAQs](https://knowledge.bigenius-x.com/faqs?hsLang=en) - [Product Release Notes](https://knowledge.bigenius-x.com/product-release-notes?hsLang=en#main-content) - [SaaS Application](https://knowledge.bigenius-x.com/product-release-notes?hsLang=en#saas-application) - [Discovery application](https://knowledge.bigenius-x.com/product-release-notes?hsLang=en#discovery-application) - [Generators](https://knowledge.bigenius-x.com/product-release-notes?hsLang=en#generators) - [Legal Documents](https://knowledge.bigenius-x.com/legal-documents?hsLang=en#main-content) - [Current legal docs](https://knowledge.bigenius-x.com/legal-documents?hsLang=en#current-legal-docs) - [Software Product and Limits](https://knowledge.bigenius-x.com/legal-documents?hsLang=en#software-product-and-limits) - [Contact us](https://knowledge.bigenius-x.com/kb-tickets/new?hsLang=en) - [Customer Portal](https://knowledge.bigenius-x.com/customer-portal) - [Sign in](https://knowledge.bigenius-x.com/_hcms/mem/login) [![biGENIUS logo](https://knowledge.bigenius-x.com/hubfs/TRI_Logo_biGENIUS_2020_RGB-1.svg "biGENIUS logo")](https://www.bigenius-x.com) All rights reserved © 2025, biGENIUS AG