24 December 2015

🪙Business Intelligence: Data Marts (Just the Quotes)

"There are four levels of data in the architected environment - the operational level, the atomic (or the data warehouse) level, the departmental (or the data mart) level, and the individual level. These different levels of data are the basis of a larger architecture called the corporate information factory (CIF). The operational level of data holds application-oriented primitive data only and primarily serves the high-performance transaction-processing community. The data-warehouse level of data holds integrated, historical primitive data that cannot be updated. In addition, some derived data is found there. The departmental or data mart level of data contains derived data almost exclusively. The departmental or data mart level of data is shaped by end-user requirements into a form specifically suited to the needs of the department. And the individual level of data is where much heuristic analysis is done." (William H Inmon, "Building the Data Warehouse" 4th Ed., 2005)

"If you think of a Data Mart as a store of bottled water, cleansed and packaged and structured for easy consumption, the Data Lake is a large body of water in a more natural state. The contents of the Data Lake stream in from a source to fill the lake, and various users of the lake can come to examine, dive in, or take samples." (James Dixon 2010)

"Many organizations need to create data warehouses—massive data stores of timeseries data for decision support. Data are imported from various external and internal resources and are cleansed and organized in a manner consistent with the organization’s needs. After the data are populated in the data warehouse, data marts can be loaded for a specific area or department. Alternatively, data marts can be created first, as needed, and then integrated into an EDW." (Ramesh Sharda et al, "Business Intelligence: A Managerial Perspective on Analytics" 3rd Ed., 2014)

"Whereas a data warehouse combines databases across an entire enterprise, a data mart is usually smaller and focuses on a particular subject or department. A data mart is a subset of a data warehouse, typically consisting of a single subject area (e.g., marketing, operations). A data mart can be either dependent or independent. A dependent data mart is a subset that is created directly from the data warehouse. It has the advantages of using a consistent data model and providing quality data. [...] An independent data mart is a small warehouse designed for a strategic business unit (SBU) or a department, but its source is not an EDW." (Ramesh Sharda et al, "Business Intelligence: A Managerial Perspective on Analytics" 3rd Ed., 2014)

"If you think of a Data Mart as a store of bottled water, cleansed and packaged and structured for easy consumption, the Data Lake is a large body of water in a more natural state. [...] The contents of the Data Lake stream in from a source to fill the lake, and various users of the lake can come to examine, dive in, or take samples." (James Dixon, "Pentaho, Hadoop, and Data Lakes", 2010) [sorce] [first known usage]

"Data mart: A subset of a data warehouse that’s usually oriented to a business group or process rather than enterprise-wide views. They have value as part of the overall enterprise data architecture, but can cause problems when they sprout uncontrolled as data silos with their own data definitions, creating data shadow systems." (Rick Sherman, "Business Intelligence Guidebook: From Data Integration to Analytics, 2015)

"Data marts promised to be quicker and cheaper to build, and provided many more benefits—including the benefit of actually being able to finish building them! The data mart was primarily a backlash to the big, cumbersome CDW projects, with the key difference being that its scope was limited to a single business group rather than the entire enterprise. Of course, that shortcut did speed things up, but at the expense of obtaining agreement on consistent data definitions, thereby guaranteeing data silos." (Rick Sherman, "Business Intelligence Guidebook: From Data Integration to Analytics, 2015)

"There are, however, many problems with independent data marts. Independent data marts: (1) Do not have data that can be reconciled with other data marts (2) Require their own independent integration of raw data (3) Do not provide a foundation that can be built on whenever there are future analytical needs." (William H Inmon & Daniel Linstedt, "Data Architecture: A Primer for the Data Scientist: Big Data, Data Warehouse and Data Vault", 2015)

"The data warehouse approach is also referred to as data marts with the usual distinction that a data mart serves a single department in an organization, while a data warehouse serves the larger organization integrating across multiple departments. Regardless of their scope, from the architectural modeling perspective they both have similar characteristics." (Zhamak Dehghani,"Data Mesh: Delivering Data-Driven Value at Scale", 2021) 

"Data marts are subject-oriented databases typically aligned with a particular business unit like sales, finance, or marketing. These are some-times called 'functional data marts' since they support specific business functions. Data marts accelerate business processes by allowing access to relevant information in a more timely nature since they are not aggregating the volume and variety (many data sources) that an EDW does. However, they are more transformed or normalized than an ODS." (Scott Burk et al, It’s All Analytics - Part II: Designing an Integrated AI, Analytics, and Data Science Architecture for Your Organization, 2022)

"Some sources try to distinguish the differences of data marts and EDWs by size. Size is a consequence and not a determinant. While EDWs are normally much larger, they are larger due to the fact they are pulling data from many sources and across business functions." (Scott Burk et al, It’s All Analytics - Part II: Designing an Integrated AI, Analytics, and Data Science Architecture for Your Organization, 2022)

"Traditional data stores used for analytics, such as data marts and data ware-houses, followed an ETL process, extract first by making a copy from the source, then transformations are made upon this copy, and then the data is loaded into the target system. ETL tools require processing engines for running transformations prior to loading data into a destination. Running these engines performing transformations before the load phase results in a more complex data replication process." (Scott Burk et al, It’s All Analytics - Part II: Designing an Integrated AI, Analytics, and Data Science Architecture for Your Organization, 2022)

"Data marts are used in most data warehouse approaches and focus on the data of a specific area, department, or domain of the business. A data warehouse focuses on building an SSOT for all data. A data warehouse can be made up of data marts (bottom-up approach), or data marts can be created from the data warehouse (top-down approach). In either case, data marts are smaller and less complicated than the data warehouse. As they only contain a subset of the data, data marts are often easier and quicker to establish. They are often managed by the departments the data mart focuses on." (Olivier Mertens & Breght Van Baelen, "Azure Data and AI Architect Handbook", 2023)

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