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Data warehousingIn addition to designing and implementing HCL OneDB™ dimensional databases, you can use tools to create data warehouse applications and optimize your data warehouse queries.
Dimensional databasesThe HCL OneDB™ Data Warehouse Guide provides information to help you design, implement, and manage dimensional databases, and describes the tools that you can use to create data warehouses and optimize your data warehouse queries.
Design a dimensional data modelTo build a dimensional database, you start by designing a dimensional data model for your business.
Building a dimensional data model
Determine the granularity of the fact tableAfter you gather all the relevant information about the subject area, the next step in the design process is to determine the granularity of the fact table.
How granularity affects the size of the databaseThe granularity of the fact table also determines how much storage space the database requires.

How granularity affects the size of the database

The granularity of the fact table also determines how much storage space the database requires.

For example, consider the following possible granularities for a fact table:

Product by day by region
Product by month by region

The size of a database that has a granularity of product by day by region would be much greater than a database with a granularity of product by month by region. The database contains records for every transaction made each day as opposed to a monthly summation of the transactions. You must carefully determine the granularity of your fact table because too fine a granularity could result in an astronomically large database. Conversely, too coarse a granularity could mean the data is not detailed enough for users to perform meaningful queries against the database.

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