Cursor-based pagination MySQL
When it comes to pagination, developers often turn to either offset limit or cursor-based pagination. While offset limit can be simple to implement, it has a few drawbacks that make it less than ideal for certain situations. Cursor-based pagination aims to address some of these flaws but comes with its own set of challenges.
Before diving deeper into cursor-based pagination, it's important to note that we're not talking about database cursors. While database cursors are interesting, they're not what we're discussing here. Cursor-based pagination references a method of pagination that is different from offset limit.
In this post, we'll explore the benefits and drawbacks of cursor-based pagination and provide an overview of its implementation.
What is cursor-based pagination?
Cursor-based pagination allows for the ability to efficiently retrieve large datasets from a database by breaking them down into smaller pages. This method is particularly useful when working with large datasets where loading all the data at once would be impractical or slow.
When implementing cursor-based pagination, developers need to keep track of the last record that the user saw. To accomplish this, a "cursor" is sent out to the front-end with each page of results. The cursor then comes back to the database as a token, indicating where the next page of results should start.
Pros and cons of cursor-based pagination
One of the advantages of cursor-based pagination is its resilience to shifting rows. For example, if a record is deleted, the next record that would have followed is still displayed since the query is working off of the cursor rather than a specific offset.
Another benefit of cursor-based pagination is that it can work well with infinite scroll, a design trend that loads content as the user scrolls.
One of the primary downsides of cursor-based pagination is that it's impossible to directly address a specific page. For instance, if the requirement is to jump directly to page five, it's not possible to do so since the pages themselves are not explicitly numbered.
Additionally, cursor-based pagination can be more complicated to implement than offset limit pagination. More thought needs to be put into the structure of the cursor and what criteria should be used to determine it.
How to implement cursor-based pagination
Cursor-based pagination requires maintaining state and intelligently reconstructing that state on demand. To achieve this, developers need to:
- Order the query results for the current page using a unique identifier like an ID or a combination of multiple fields.
- Calculate the "cursor" based on the last record.
- Send the results and the cursor back to the user.
- On the next request, extract the cursor, deconstruct the state from it, and construct the query.
While cursor-based pagination may not be the ideal solution for all situations, it's a powerful tool for managing large datasets that and can address many of the issues that offset limit pagination can't. When comparing offset limit vs. cursor-based pagination, consider the specific requirements of your project and your user expectations. With thoughtful consideration, you can choose the pagination method that best suits your specific needs.