What are the benefits and drawbacks of using identity columns as surrogate keys in SQL?

I think an interesting point to highlight about the identity column is that it's a practical conceptual to generate value on the column that you maybe replicate it: the most popular database have triggers feature to change value, if the function associated with tiggrer allows to use external libreries on the code; you can generate interesanting values based on your custom business requirements. If well it reduces the compabitility between databases; you must evaluate if you can replicate it with theirs components.

Using identity columns as surrogate keys in SQL has its benefits and drawbacks. Benefits: 1. Automatically generated, ensuring uniqueness without manual effort. 2. Independent of business logic, making them stable even if natural keys change. 3. Improve performance in indexing and joins due to consistent format. Drawbacks: 1. Lack of inherent meaning, making data less intuitive. 2. Can lead to fragmentation if not managed well. 3. Reliance solely on identity columns can overlook the importance of meaningful natural keys.

Using identity columns as surrogate keys in SQL provides several advantages; They automatically generate unique identifiers for each row, ensuring efficient data management without the need for manual input. Since these keys are not tied to any business logic, they offer greater flexibility, allowing changes in business rules without affecting data integrity. Additionally, identity columns improve performance by simplifying indexing and speeding up queries and joins. Their independence also facilitates easier replication and migration across systems, making database management smoother and more scalable.

As an intro, identity columns are columns that automatically generate a unique value each time a new row is inserted. The values are typically numeric.

Using identity columns as unique IDs in databases has its pros and cons. They’re simple, automatically generated, and great for managing large amounts of data efficiently. These IDs don’t change when data changes, making relationships easier to handle. However, they lack meaning for users, can create gaps if data is deleted, and may depend on specific database features. While ideal for complex systems, they might not suit cases where IDs need to be meaningful or easily portable. Choosing them depends on balancing simplicity and the specific needs of your data.

One of the serious and perhaps most significant drawback of using identity columns as auto incremented SK is fragmentation and possible missing or duplicate records during broken ETL upserts. To mitigate this, we need to take a hash function (like MD5) of the natural keys or composite key combinations and retain them in the DWH, and can also be converted to a base 16 int to support faster joins while ensuring referential integrity.

Lack of semantic meaning: Identity columns don't provide any meaningful information about the record they represent. Difficulty with updates: If the original data used to generate the identity column changes, it becomes difficult to update the corresponding record. Potential for gaps: If identity columns are deleted or reused, gaps may appear in the sequence. ? Performance concerns: While identity columns can improve performance in some cases, they can also introduce additional overhead, especially in large databases. Identity columns are generated automatically, limiting flexibility in assigning unique identifiers.? Dependency on database engine: The behavior of identity columns can vary between different database engines.

Drawbacks: No Meaning: The numbers don't represent anything useful about the data. Migration Issues: Moving data across systems can lead to duplicate key problems. Extra Joins: You may need more table joins to get meaningful information. Data Integrity: Focusing only on surrogate keys may ignore important business rules that natural keys could help enforce.

Alternatives to identity columns that can act as surrogate keys in SQL include: Sequences: Generate unique numbers using a sequence object, providing more control over the starting value, increment, and maximum value. GUIDs (Globally Unique Identifiers): Create unique identifiers that are guaranteed to be unique across all systems and databases. ? Custom-generated keys: Develop your own algorithm to generate unique keys based on specific requirements, such as combining timestamps, random numbers, or other data. Hash functions: Apply hash functions to data to create unique hash values that can be used as surrogate keys. ? Trigger-based approaches: Use triggers to automatically generate unique keys when new rows are inserted into a table.

Some alternatives to using identity columns in SQL: UUIDs (Universally Unique Identifiers): These provide unique values across different systems, useful for distributed databases. However, they are longer and can slow down performance. Natural Keys: Use real data, like emails or product codes, as the key. This makes sense for certain datasets but can cause issues if the data changes. Composite Keys: Combine multiple columns to create a unique key. It's helpful for capturing relationships, but managing multiple columns can be tricky. Sequence Objects: Some databases allow you to use sequences that generate unique numbers independently, offering flexibility without needing identity columns.

Consider data characteristics: Assess whether your data has a natural key or needs a surrogate key. Choose a suitable data type: Select a data type that can accommodate the expected range of values and aligns with your database's capabilities. Implement error handling: Include mechanisms to handle errors or conflicts that may arise during surrogate key generation. Test and optimize: Thoroughly test your chosen surrogate key implementation to ensure it meets your requirements and optimize performance if necessary. Consider future scalability: Evaluate how your chosen surrogate key approach will handle future growth and changes in your data. Strike a balance between a simple implementation and optimal performance.