Exploring the Pros and Cons of Using Surrogate Keys
Sep 10, 2023 8:29 PM

Exploring the Pros and Cons of Using Surrogate Keys

by HubSite 365 about Guy in a Cube

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Understand the significance of using surrogate keys in your data warehouse with our Microsoft experts insights!

Video Summary: Understanding Surrogate Key in Data Warehouses

The YouTube video from the author "Guy in a Cube" centers around the use of surrogate keys in data warehouses. It delves into explaining the need, functioning and the impact of Surrogate Keys (SK) in featurizing databases irrespective of the data warehouse tool being used such as Azure Synapse Analytics. In context, the potential benefits and drawbacks of using surrogate keys in this database framework are also highlighted.

Surrogate Key is broadly described as a sequentially generated unique number, which is meaningless, attached with each record in any database table. It plays a substantial role in data management and provides benefits such as saving storage space and improving data retrieval speed, but alongside it carries certain disadvantages like creating additional ETL burden and complicating data integration and migration.

The video emphasizes how surrogate keys are not directly derived from the application data, which results in a level of abstraction. This characteristic is beneficial as even when the underlying data changes, the surrogate key remains unaffected.

Why Surrogate Key?

Surrogate Key is appealing for a data warehouse due to its ability to help facilitate faster data retrieval and lookups. It is an integer attached to a record for joining various tables in database models such as the Star or Snowflake schemas, proving useful when natural keys are too lengthy or are not ideal for indexing. Additionally, these keys play an essential role in minimizing storage space and offering data abstraction.

Ralph Kimball and Thomas Kejser are quoted in the video, stressing the importance of surrogate keys not being derived or composed of natural keys. Moreover, the benefits of a “good key” are mentioned, with a surrogate key fitting this description as it is unique, small, integer-based, does not change once assigned, and is never re-used.

Challenges with Surrogate Key

Despite its advantages, using surrogate keys also present drawbacks including the potential loss of real-world meaning, increased ETL processing burden, and complexity in data integration and migration. Furthermore, a proper surrogate key generating area has to be maintained to ensure their uniqueness. In situations with duplicate records from the source, the risk of duplicates being loaded into the target also exists.

The video from "Guy in a Cube" contributes a nuanced understanding of Surrogate Keys in data warehousing, acknowledging both the significant benefits and potential challenges of the same.

Broader Context of Surrogate Keys

Surrogate keys are fundamental to the management and organization of data in databases, serving as unique identifiers for entities in a database table. They function as substitutes for natural keys, which might not always guarantee uniqueness. Whether generated automatically by the database system or assigned manually, these keys help maintain the integrity and the organization of the data in a database.

SQL  and SQL Server - Exploring the Pros and Cons of Using Surrogate Keys

Learn about To Surrogate Key or Not...

Surrogate Keys(SKs) are sequentially generated numbers in data warehouses, mainly Azure Synapse Analytics. Their primary role involves supporting changes in dimension table attributes. Thus, they function as unique IDs connected to each record in a dimension table.

A SK is unique, meaningless, and sequential. Its uniqueness is because it's a sequentially produced integer for each record inserted in the table. It's meaningless as it carries no business connotation concerning any table record it's linked to. Lastly, it retains a sequential nature as its assignment follows a pattern, starting from one and ascending to the highest number needed.

During a FACT table load, various dimensional properties get looked up in corresponding Dimensions, and SKs get fetched from there. These SKs should ideally be acquired from the most recent versions of these dimension records. Consequently, the FACT table in the data warehouse houses actual data coupled with accompanying SKs from Dimension tables.

Surrogate keys are prevalent as a surrogate for Natural Key(NK) in organizing different tables in a Star or Snowflake schema-based data warehouse. It plays a significant role when having a long NK, or if the NK's datatype is unsuitable for Indexing.

Surrogate keys offer several benefits like saving storage space, improving join performance, upholding data abstraction, and more. That notwithstanding, they also present their drawbacks, including leading to problems of disassociation, creating an unnecessary ETL load, query optimization becomes difficult, and potential risk of duplicates.

To learn more about the topic, your options could include various training courses. Online platforms such as Udacity, Coursera, and LinkedIn Learning offer numerous related courses, mainly dealing with data warehouse management, database systems, and SQL Server operations.

For a practical understanding, consider utilizing Azure Synapse Analytics, where you can comprehensively apply the surrogate key concept. With mapping data flows available in Azure Data Factory and Azure Synapse Pipelines, you can delve deeper into transforming data effectively.

Before deciding to incorporate a surrogate key, consider whether we need an NK to uniquely pinpoint a record or when using an SK looks more practical because the NK doesn't adequately fit as a PK.

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