Lazy loading and handling soft deletes in SQL.

21 Sep 2023

In any software application, the efficient utilization of database resources is crucial for optimal performance. Lazy loading and handling soft deletes are two techniques that can help in achieving this goal.

Lazy Loading

Lazy loading is a technique where data is loaded only when it is actually needed, rather than loading all the data at once. This can greatly improve performance, especially when dealing with large datasets.

In SQL, lazy loading can be implemented using pagination. Rather than fetching all the data in a single query, we can retrieve a specific number of rows per query based on the requested page size. This can be accomplished using the LIMIT and OFFSET clauses in SQL queries.

For example, let’s say we have a table called users with millions of records. Instead of fetching all the records at once, we can use pagination to retrieve, let’s say, 100 records per query using the following query:

SELECT * FROM users LIMIT 100 OFFSET 0;

By keeping track of the offset value, we can load subsequent pages lazily as needed. This ensures that only the necessary amount of data is fetched, resulting in better performance.

Handling Soft Deletes

Soft deletes are a way to logically delete records from a database without permanently removing them. This is often achieved by adding a flag column to the table, such as is_deleted, which is set to true for deleted records.

When handling soft deletes in SQL, it is important to consider them in queries to ensure that deleted records are not included in the results. This can be done by adding a condition to exclude the deleted records.

For example, let’s say we have a table called orders, and we want to retrieve all active orders:

SELECT * FROM orders WHERE is_deleted = false;

By adding the condition WHERE is_deleted = false, we can ensure that only non-deleted records are returned in the result.

It is also a good practice to include an indexed column, such as deleted_at, to keep track of when a record was soft deleted. This can be useful for auditing purposes or to retrieve deleted records if needed.

#SQL #LazyLoading #SoftDeletes