--- title: Hub description: A Hub stores each business key of a business object once, with its hash key Hub_HK, in a table of the Raw Vault layer. --- [Skip to content](https://knowledge.bigenius-x.com/create-a-hub#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) # Hub **Applies to** Platform: Microsoft SQL Server · Snowflake · Snowflake dbt · Databricks · Databricks dbt · Fabric Lakehouse · Fabric Warehouse · Oracle Architecture: Data Vault A Hub stores each business key of a business object once, with its hash key `Hub_HK`, in a table of the Raw Vault layer. Use it as the anchor that Links and Satellites reference. After each load, the result view shows one row per business key and the load that first delivered it. ### Sources and relationships A Hub 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 no relationships of its own. Other model objects use it in two ways: - Relationship to the Hub: Link, Driving Key Link, Hierarchical Link, Same As Link, Satellite, Multi-Active Satellite, Record Tracking Satellite, Effectivity Satellite and Non-Historized Satellite (no article yet), and their Business Vault counterparts. - Dataflow source: Current View, History View, PIT, BusinessVault Composite, [Vault Out](https://knowledge.bigenius-x.com/create-a-vault-out?hsLang=en) and the Business Vault types. ### Create a Hub - With the wizard: open the menu of a Stage, RawVault Composite or Store Entity, choose **Automate** and then **Create Hub**. 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), [Map Selected Business Keys](https://knowledge.bigenius-x.com/wizard-step-map-selected-business-keys?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). ![Menu of the Stage CUSTOMER with Automate and its list of Data Vault wizards, Create Hub highlighted](https://knowledge.bigenius-x.com/hs-fs/hubfs/knowledge_base_screenshots/create-a-hub-automate-menu.png?width=478&height=558&name=create-a-hub-automate-menu.png) - Manually: [create a model object](https://knowledge.bigenius-x.com/create-a-model-object?hsLang=en) of type Hub in the Raw Vault layer, [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 terms](https://knowledge.bigenius-x.com/map-a-source-term-with-a-target-term?hsLang=en). Mark at least one term as business key. A Hub holds only business keys and Default Terms. Validation reports an error for any other term. ### Properties - [Implementation Type](https://knowledge.bigenius-x.com/implementation-type-model-object?hsLang=en): `Permanent` only, a table that keeps its rows from load to load. - [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. Available since Generator 2.3. - [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. Platform-specific properties are listed under Platform differences. ### Default Terms - [`Hub_HK`](https://knowledge.bigenius-x.com/hub_hk?hsLang=en): hash of the business keys 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). - [`BG_LoadTimestamp`](https://knowledge.bigenius-x.com/bg_loadtimestamp?hsLang=en): the load that inserted the business key. - [`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. The business keys form a unique constraint of the table. ### Generated objects These are the names on Microsoft SQL Server for the Hub `load_customer_hub` with one dataflow: | Role | Generated name | Purpose | | --- | --- | --- | | Source | `RDV_HUB_load_customer_hub_Source` | Reads the sources | | Deduplication | `RDV_HUB_load_customer_hub_Deduplication` | Removes duplicate rows | | Hashing | `RDV_HUB_load_customer_hub_Hashing` | Calculates `Hub_HK` | | HashingStorage | `RDV_HUB_load_customer_hub_HashingTable` | Stores the hashed rows | | HashingLoader | `RDV_HUB_load_customer_hub_HashingLoader` | Fills the hashing table | | Delta | `RDV_HUB_load_customer_hub_Delta` | Selects new business keys | | Loader | `RDV_HUB_load_customer_hub_Loader` | Inserts the new keys | | Storage | `RDV_HUB_load_customer_hub` | Hub table | | Result | `RDV_HUB_load_customer_hub_Result` | Query view | - Loaders are stored procedures; the Hub 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. - With several dataflows, all objects except the table and the result view exist once per dataflow. Their names carry the dataflow name, for example `RDV_HUB_load_customer_hub_Dataflow1_Loader`. - The table script inserts the unknown-member row: business key `0` (text terms `Unknown`), a `Hub_HK` of zeros, `BG_SourceSystem` `Unknown` and `BG_LoadTimestamp` 1900-01-01. The result view hides this row. Link rows with an empty foreign key reference it. - 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_HUB_load_customer_hub -> _Result _Result -> _Delta (keys already stored) ``` The delta view keeps the rows whose `Hub_HK` is not in the result view. The loader inserts them with the load timestamp. A Hub loader never updates or deletes rows. With the optional objects, `_Deduplication` sits between `_Source` and `_Hashing`, and `_HashingLoader` fills `_HashingTable` before the delta view reads it. ### Example The Hub `load_customer_hub` on Microsoft SQL Server reads the Stage `CUSTOMER`. `CUSTOMER_ID` is the business key. The loads deliver these keys: - Load 1 on 2026-10-28 08:00: customers 1 and 2. - Load 2 on 2026-10-29 08:00: customers 1, 2 and 3. - Load 3 on 2026-10-30 08:00: the same keys as load 2. ### Check the result Query the result view, here in the schema `rv`: ``` SELECT CUSTOMER_ID, Hub_HK, BG_LoadTimestamp FROM rv.RDV_HUB_load_customer_hub_Result ORDER BY CUSTOMER_ID; ``` This is the result after load 3, with `Hub_HK` shortened to its first four bytes: ``` CUSTOMER_ID Hub_HK BG_LoadTimestamp 1 0xE91FE173 2026-10-28 08:00 2 0x21ED4C7A 2026-10-28 08:00 3 0x2064F80F 2026-10-29 08:00 ``` - Load 2 inserted only customer 3, so customers 1 and 2 keep the timestamp of load 1. - Load 3 inserted no row. - The table holds a fourth row, the unknown-member row with `CUSTOMER_ID` 0. With two dataflows, each dataflow loader inserts only the keys that are not yet stored. For example, when the first dataflow delivers customers 1 and 2 and the second one customers 2 and 7, the Hub stores customer 2 once. ### Platform differences - Snowflake: names are in capitals, and the loader is a stored procedure. The load control task `LC_RDV_HUB_` calls it. 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_HUB__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. - Databricks dbt and Snowflake dbt: the Hub becomes the dbt models `rdv_hub__source` and `rdv_hub_`. The model `rdv_hub__result` exists only when Create Result Views is true; the default on dbt is false. Load Caching is not available. File Format and the optimization properties apply on Databricks dbt. - 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, for example `PARTITION BY HASH (CUSTOMER_ID) PARTITIONS 4`. Table Compression, Tablespace Table, Tablespace Index, Create Table Statistics and Parallel Degree of Statistics Calculation also apply. ### Limitations - A Hub has at least one business key, no relationships and no terms other than business keys and Default Terms. - A dataflow that delivers the same business key twice in one load makes the loader fail. On Microsoft SQL Server the message is `Violation of PRIMARY KEY constraint 'PK_RDV_HUB_'`. Deduplication Method `Distinct` or `Partition` removes such duplicates before hashing. - A Hub keeps no history. Satellites store the descriptive data of its keys. ### Related articles - Previous: [Stage](https://knowledge.bigenius-x.com/create-a-stage?hsLang=en), [RawVault Composite](https://knowledge.bigenius-x.com/create-a-raw-vault-composite?hsLang=en), [Store Entity](https://knowledge.bigenius-x.com/create-a-store-entity?hsLang=en) - Next: [Link](https://knowledge.bigenius-x.com/create-a-link?hsLang=en), [Satellite](https://knowledge.bigenius-x.com/create-a-satellite?hsLang=en) - Reference: [Hub\_HK](https://knowledge.bigenius-x.com/hub_hk?hsLang=en), [Implementation Type (Model Object)](https://knowledge.bigenius-x.com/implementation-type-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), [Deduplication Method (Dataflow)](https://knowledge.bigenius-x.com/deduplication-method-model-object?hsLang=en), [Sort Order within Partition (Dataflow)](https://knowledge.bigenius-x.com/deduplication-partition-model-object?hsLang=en), [Create Result Views (Project)](https://knowledge.bigenius-x.com/create-result-views-project?hsLang=en) - 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