--- title: Hub_HK description: Hub_HK is the hash key that identifies a business key in a Hub. --- [Skip to content](https://knowledge.bigenius-x.com/hub_hk#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. [Default Terms](https://knowledge.bigenius-x.com/generators?hsLang=en#default-terms) # Hub\_HK **Applies to** Platform: Microsoft SQL Server · Snowflake · Snowflake dbt · Databricks · Databricks dbt · Fabric Lakehouse · Fabric Warehouse · Oracle Architecture: Data Vault `Hub_HK` is the hash key that identifies a business key in a Hub. Satellites carry the same value to reference their Hub. ### Objects that carry it - Hub and Business Hub: the identity and primary key of the table. - Satellite, Multi-Active Satellite, Effectivity Satellite, Record Tracking Satellite, Non-Historized Satellite and their Business Vault counterparts: the reference to the Hub, part of the primary key. Every object of these types gets the term when it is created. The generator calculates the value, so you do not map it; you can change its data type in Manage Default Terms. ### Value In a Hub, the generated Hashing view hashes the business-key terms of the Hub in their term order, with the project [Hash Algorithm](https://knowledge.bigenius-x.com/hash-algorithm-project?hsLang=en). A satellite hashes its foreign-key terms that are mapped to the business keys of the Hub, in the term order of the Hub. The same business key therefore gets the same value in the Hub and in all its satellites. How the term values are prepared and joined is explained in [How biGENIUS-X builds hash values](https://knowledge.bigenius-x.com/how-bigenius-x-builds-hash-values?hsLang=en). The unknown-member row has a `Hub_HK` that consists of zero bytes only. [Custom Singleton Values](https://knowledge.bigenius-x.com/custom-singleton-values-model-object?hsLang=en) does not change this value. ### Data type | Platform | Type | | --- | --- | | Microsoft SQL Server | `binary(20)` | | Fabric Warehouse | `varbinary(20)` | | Oracle | `RAW(20)` | | Snowflake, Snowflake dbt | `BINARY(32)` | | Databricks, Databricks dbt, Fabric Lakehouse | `binary` | The data type must match the length of the selected [Hash Algorithm](https://knowledge.bigenius-x.com/hash-algorithm-project?hsLang=en). ### Example A Hub on Microsoft SQL Server has the business key `CUSTOMER_ID`, with default hash settings. Its Hashing view calculates: ``` CAST(HASHBYTES('SHA1', CAST('' AS VARCHAR(MAX)) + ISNULL(CAST([CUSTOMER_ID] AS NVARCHAR(4000)), N'_NULL_')) AS VARBINARY(20)) AS [Hub_HK] ``` After the first load the Hub holds these rows. The Satellite rows of customers 940 and 941 carry the same `Hub_HK` values: ``` CUSTOMER_ID Hub_HK 0 0x0000000000000000000000000000000000000000 940 0xE50BE2BB58C7F15F16B0D583FFACC4E6951F14FB 941 0xD2CD1706C57ACAAF24EB90BD2A4039D4D855DDF1 ``` The row with `CUSTOMER_ID` 0 is the unknown member. ### Release differences - Generator 2.4: Snowflake uses SHA2-256 with `BINARY(32)` by default. Up to Generator 2.3 the default was `HASH` with a numeric type, see [Generators Release - 2.4.0](https://knowledge.bigenius-x.com/generators-release-2.4.0?hsLang=en). - Generator 2.2: Databricks and Fabric Lakehouse store hash values as `binary`. Up to Generator 2.0 they were `string`. ### Related articles - Reference: [Hash Algorithm (Project)](https://knowledge.bigenius-x.com/hash-algorithm-project?hsLang=en), [Link\_HK](https://knowledge.bigenius-x.com/link_hk?hsLang=en), [PIT\_HK](https://knowledge.bigenius-x.com/pit_hk?hsLang=en), [BG\_RowHash](https://knowledge.bigenius-x.com/bg_rowhash?hsLang=en) - See also: [How biGENIUS-X builds hash values](https://knowledge.bigenius-x.com/how-bigenius-x-builds-hash-values?hsLang=en), [Hub](https://knowledge.bigenius-x.com/hub?hsLang=en), [Satellite](https://knowledge.bigenius-x.com/satellite?hsLang=en), [Manage Default Terms](https://knowledge.bigenius-x.com/manage-default-terms?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) - 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