Data Warehouse Loads

In a data warehousing environment, data is typically loaded into the data warehouse from various source systems through a process known as ETL (Extract, Transform, Load). The "Load" phase of ETL involves loading the transformed and processed data into the data warehouse for storage and analysis. There are different types of loads used in this process, each serving a specific purpose.

 

Here are the main types of loads in data warehousing:

 

Full Load:

In a full load, all the data from the source system is extracted and loaded into the data warehouse.

This type of load is typically used for the initial population of the data warehouse or when performing periodic full refreshes of data.

Full loads can be time-consuming and resource-intensive, especially for large datasets, but they ensure that the data in the warehouse is complete and up-to-date.

 

Incremental Load:

In an incremental load, only the new or changed data since the last load is extracted and loaded into the data warehouse.

Incremental loads are used to keep the data warehouse up-to-date with changes in the source systems while minimizing the amount of data processed and loaded.

This type of load is often more efficient than full loads, especially for large datasets where only a small portion of the data changes frequently.

 

Delta Load:

A delta load is a variation of an incremental load where only the changed data, or "delta," is extracted and loaded into the data warehouse.

Instead of extracting all the new or changed data since the last load, a delta load only extracts the specific records that have been added, updated, or deleted.

Delta loads are useful for optimizing the ETL process and reducing the processing time and resources required for incremental updates.

 

Initial Load:

An initial load, also known as a baseline load or seed load, is performed during the initial setup of the data warehouse.

It involves loading the entire dataset from the source systems into the data warehouse for the first time.

Initial loads are typically followed by incremental or delta loads to keep the data warehouse synchronized with ongoing changes in the source systems.

 

Historical Load:

A historical load involves loading historical or archival data into the data warehouse.

This type of load is used to populate the data warehouse with historical data that may not have been captured in real-time or may have been stored in separate systems.

Historical loads are often performed as part of the initial setup of the data warehouse or when integrating data from legacy systems or historical records.

 

Real Time Load:

In a real-time load, data is loaded into the data warehouse immediately or shortly after it becomes available in the source systems.

This type of load is used for streaming or near-real-time data integration, where timely analysis of fresh data is critical.

Real-time loads require robust data integration and processing capabilities to handle high volumes of data with low latency.