Periodic Fact Tables

Periodic Fact Tables: A Detailed Explanation

Periodic fact tables are a type of fact table that aggregates data over specific time periods, such as daily, weekly, monthly, or quarterly. They provide a summarized view of business activities, making it easier to analyze trends and patterns over time. 

Key Characteristics:

• Aggregated Data: Store aggregated data for specific time periods.

• Reduced Detail: Provide a less granular view of data compared to transactional fact tables.

• Periodic Updates: Updated less frequently than transactional fact tables, typically at the end of each period.

Examples:

• Monthly Sales Summary: Aggregates sales data for each month, providing total sales, average order value, and other key metrics.

• Quarterly Profitability Report: Summarizes profitability data for each quarter, including revenue, costs, and net profit.

• Daily Inventory Snapshot: Captures the inventory levels for each product on a daily basis.

Benefits of Periodic Fact Tables:

• Improved Performance: Can improve query performance for analytical reports that require aggregated data.

• Reduced Storage Requirements: Store less data compared to transactional fact tables.

• Simplified Analysis: Easier to analyze trends and patterns over time.

Challenges:

• Loss of Detail: May lose some level of detail compared to transactional fact tables.

• Update Frequency: Need to be updated periodically to ensure data accuracy.

When to Use Periodic Fact Tables:

• Trend Analysis: When you want to analyze trends and patterns over time.

• High-Level Reporting: When you need to generate summary reports at a periodic level.

• Performance Optimization: To improve query performance for analytical workloads.

By understanding the characteristics and benefits of periodic fact tables, you can effectively design and use them to meet your data warehousing and reporting needs.

Example: Monthly Sales Summary

Periodic Fact Table: MonthlySales

Year	Month	ProductID	TotalSales	AverageOrderValue	UnitsSold
2023	10	101	10000.00	200.00	50
2023	10	102	8000.00	160.00	40
2023	11	101	12000.00	240.00	60
2023	11	102	9000.00	180.00	45
...	...	...	...	...	...

Explanation:

• This periodic fact table summarizes sales data for each month.

• The Year and Month dimensions provide the time period for the aggregation.

• The ProductID dimension identifies the product.

• The TotalSales, AverageOrderValue, and UnitsSold measures are aggregated values for the month.

Key Points:

• Periodic fact tables provide a summarized view of data, making it easier to analyze trends and patterns over time.

• They are typically updated less frequently than transactional fact tables, as they aggregate data for specific periods.

• Periodic fact tables can be used for various reporting and analysis purposes, such as sales performance analysis, customer segmentation, and financial reporting.

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