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Heba Allah Hashim
Heba Allah Hashim

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Data Warehouse

Definition

  • A central repository of information that can be analyzed to make more informed decisions.

  • A data warehouse is specially designed for data analytics, which involves reading large amounts of data to understand relationships and trends across the data.

  • A data warehouse requires that the data be organized in a tabular format.


Architectures

  • Data Source Layer: Operational systems, CRM, ERP, and external files (Excel, JSON, SQL) that provide raw data.

  • Data Staging Area: A temporary storage area where data is cleaned, transformed, and integrated before loading into the main warehouse.

  • Storage Layer (Warehouse/Data Marts): The central database (RDBMS or Cloud) holding historical and structured data. It may use a Star or Snowflake Schema for organizing data.

  • Data Access/Analytics Layer: Front-end tools for reporting, dashboards, and BI (e.g., SQL tools, Tableau).

  • Metadata Layer: Data that describes the structure, relationships, and context of the stored data.


Benefits

  • Informed decision making
  • Consolidated data from many sources
  • Historical data analysis
  • Data quality, consistency, and accuracy
  • Separation of analytics processing from transactional databases, which improves the performance of both systems

ETL (Extract Transform Load)

Definition:
is the process of combining data from multiple sources into a large, central repository called a data warehouse, By applying the process of extract, transform, and load (ETL).


OLAP (Online analytical processing)

Definition:
is a technology used to analyze data stored in a data warehouse by organizing it into multiple dimensions, enabling fast queries and meaningful business insights.


Data modeling

Data modeling: is the representation of data in data warehouses or online analytical processing (OLAP) databases as a star or snowflake schema.


Operations

  • Roll up
  • Drill down
  • Slice
  • Dice
  • Pivot

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