OLAP - online analytical processing
OLAP (online analytical processing) is a computing method that enables users to easily and selectively extract and query data in order to analyze it from different points of view. OLAP business intelligence queries often aid in trends analysis, financial reporting, sales forecasting, budgeting and other planning purposes.
To facilitate this kind of analysis, data is collected from multiple data sources and stored in data warehouses then cleansed and organized into data cubes. Each OLAP cube contains data categorized by dimensions (such as customers, geographic sales region and time period) derived by dimensional tables in the data warehouses. Dimensions are then populated by members (such as customer names, countries and months) that are organized hierarchically.
Analysts can then perform five types of online analytical processing system operations against these multidimensional databases:
- Roll-up. Also known as consolidation, or drill-up, this operation summarizes the data along the dimension.
- Drill-down. This allows analysts to navigate deeper among the dimensions of data, for example drilling down from "time period" to "years" and "months" to chart sales growth for a product.
- Slice. This enables an analyst to take one level of information for display
- Dice. This allows an analyst to select data from multiple dimensions to analyze
- Pivot. Analysts can gain a new view of data by rotating the data axes of the cube.
OLAP software then locates the intersection of dimensions, such as all products sold in the Eastern region above a certain price during a certain time period, and displays them. The result is the "measure"; each OLAP cube has at least one to perhaps hundreds of measures, which are derived from information stored in fact tables in the data warehouse.
Types of OLAP:
- Relational online analytical processing (ROLAP): ROLAP is an extended RDBMS along with multidimensional data mapping to perform the standard relational operation.
- Multidimensional OLAP (MOLAP): MOLAP Implementes operation in multidimensional data.
- Hybrid OnlineAnalytical Processing (HOLAP): In HOLAP approach the aggregated totals are stored in a multidimensional database while the detailed data is stored in the relational database. This offers both data efficiency of the ROLAP model and the performance of the MOLAP model.
- Desktop OLAP (DOLAP): In Desktop OLAP system, a user downloads a part of the data from the database locally, or on their desktop and analyze it. DOLAP is relatively cheaper to deploy as it offers very few functionalities compares to other OLAP tools.
- Web based OLAP (WOLAP): Web OLAP which is OLAP system accessible via the web browser. WOLAP is a three-tiered architecture. It consists of three components: client, middleware, and a database server.
- Mobile OLAP: Mobile OLAP process helps users to access and analyze OLAP data using their mobile devices
- Spatial OLAP: SOLAP is created to facilitate management of both spatial and non-spatial data in a Geographic Information system (GIS)
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F.A.Q. about OLAP - online analytical processing
Implementing an OLAP Solution
Implementation of OLAP depends not only on the type of software, but also on underlying data sources and the intended business objective(s). Each industry or business area is specific and requires some degree of customized modeling to create multidimensional “cubes” for data loading and reporting building, at minimum. An OLAP program might be intended for dynamic reporting for finance professionals, with source data originating in an ERP system. Or a solution might address a medical institution’s activities as concerns patient analysis. All of which is to say that customers need to have clear objectives in mind for an intended solution, and start to consider product selection on that basis. Another factor to consider in an OLAP implementation is the delivery to end users: does the initial user base want to adopt a new front end, or is there a preference for utilizing a dashboard? Or perhaps users are better served by a dynamic spreadsheet “delivery” system to achieve, for example, a collaborative budgeting and forecasting solution.
Advantages and Disadvantages of OLAP
- OLAP is a platform for all type of business includes planning, budgeting, reporting, and analysis.
- Information and calculations are consistent in an OLAP cube. This is a crucial benefit.
- Quickly create and analyze "What if" scenarios
- Easily search OLAP database for broad or specific terms.
- OLAP provides the building blocks for business modeling tools, Data mining tools, performance reporting tools.
- Allows users to do slice and dice cube data all by various dimensions, measures, and filters.
- It is good for analyzing time series.
- Finding some clusters and outliers is easy with OLAP.
- It is a powerful visualization online analytical process system which provides faster response times
- OLAP requires organizing data into a star or snowflake schema. These schemas are complicated to implement and administer.
- You cannot have large number of dimensions in a single OLAP cube.
- Transactional data cannot be accessed with OLAP system.
- Any modification in an OLAP cube needs a full update of the cube. This is a time-consuming process.