--- title: Hash Group Size (Model Object) description: Hash Group Size (HashGroupSize) splits the row hash of an Oracle model object into group hashes, so that each hash input stays below the Oracle limit. --- [Skip to content](https://knowledge.bigenius-x.com/hash-group-size-model-object#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. [Properties](https://knowledge.bigenius-x.com/generators?hsLang=en#properties) # Hash Group Size (Model Object) **Applies to** Platform: Oracle Architecture: Data Store · Data Vault · Data Mart Hash Group Size (`HashGroupSize`) splits the row hash of an Oracle model object into group hashes, so that each hash input stays below the Oracle limit. Use it on wide objects whose load fails with ORA-01489. ### Supported objects Set it in Edit Model Object, Hashing group, on these model object types: - Data Vault: Satellite, Link Satellite, Multi-Active Satellite, Business Satellite, Business Link Satellite, Reference Table - Data Store: Store Entity - Data Mart: Mart Dimension ### Values and default - Empty (default): no grouping. - A whole number from 1: the terms per group. Other values stop the generation of the object with the validation error `Model object has non numeric hash group size configured.` or `Model object has hash group size smaller than 1 configured.` ### Effect on generated output - Only the row hashes [BG\_RowHash](https://knowledge.bigenius-x.com/bg_rowhash?hsLang=en), [BG\_RowHashScd1](https://knowledge.bigenius-x.com/bg_rowhashscd1?hsLang=en) and [BG\_RowHashScd2](https://knowledge.bigenius-x.com/bg_rowhashscd2?hsLang=en) are grouped. Key hashes such as Hub\_HK are never grouped. - The terms are split in term order into groups of the given size; the last group holds the rest. - The row hash is `STANDARD_HASH` over the group hashes, joined with the Hash Concatenation Separator. All hashes use the project [Hash Algorithm](https://knowledge.bigenius-x.com/hash-algorithm-project?hsLang=en). - A hash with no more terms than the group size has no groups. BG\_RowHashScd1 and BG\_RowHashScd2 are decided separately. Term values are prepared as in [How biGENIUS-X builds hash values](https://knowledge.bigenius-x.com/how-bigenius-x-builds-hash-values?hsLang=en). ### Choose the group size Oracle stops a hash with `ORA-01489: result of string concatenation is too long` when its input exceeds the maximum string length: 4,000 bytes with `MAX_STRING_SIZE = STANDARD`. A character of two bytes counts twice. - The longest values of one group, with the separators, must fit. - The group hashes must fit as well: each SHA1 group adds 40 characters plus the separator, so at most 97 groups fit. ### Example A Satellite with the terms `CUSTOMER`, `CUSTOMER_TYPE` and `CUSTOMER_SINCE` has Hash Group Size `2`. Its Hashing view calculates two groups: ``` STANDARD_HASH( STANDARD_HASH(NVL(CUSTOMER, '_NULL_') || '_' || NVL(CUSTOMER_TYPE, '_NULL_'), 'SHA1') || '_' || STANDARD_HASH( NVL(TO_CHAR(CUSTOMER_SINCE, 'YYYYMMDDHH24MISS'), '_NULL_'), 'SHA1') , 'SHA1') AS BG_ROWHASH ``` The row `Contoso Ltd`, `Business`, 2019-03-01 gives: ``` Hash Group Size BG_ROWHASH 2 BD00B21F51F3F506ADBF37B39F165EB1B906F8D2 empty B0F8890E411EF2C10CE48AB58D83605D21DA83F7 ``` ### Changing the value on loaded objects Changing Hash Group Size on a model object that already holds data changes its row hash when the object has more hashed terms than the old or the new value. The next load treats these rows as changed and writes a new version for each affected key. Set the value before the first load, or plan for these additional versions. Available since Generator 2.3. ### Related articles - Reference: [Hash Algorithm (Project)](https://knowledge.bigenius-x.com/hash-algorithm-project?hsLang=en), [BG\_RowHash](https://knowledge.bigenius-x.com/bg_rowhash?hsLang=en), [BG\_RowHashScd1](https://knowledge.bigenius-x.com/bg_rowhashscd1?hsLang=en), [BG\_RowHashScd2](https://knowledge.bigenius-x.com/bg_rowhashscd2?hsLang=en) - See also: [How biGENIUS-X builds hash values](https://knowledge.bigenius-x.com/how-bigenius-x-builds-hash-values?hsLang=en), [Generators Release - 2.3.0](https://knowledge.bigenius-x.com/generators-release-2.3.0?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) - 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