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Cursor-Based Pagination

Cursor-based pagination, also known as keyset pagination, is a technique used to manage large datasets by navigating through records using a continuously updating pointer or "cursor."

This method is different from traditional offset pagination, as it does not rely on skipping a specified number of records but rather on continuing from the exact location where the last query stopped.

How Does Cursor-Based Pagination Work​

Cursor-based pagination requires a unique identifier (often a timestamp or an auto-incrementing ID) to determine the position in the dataset. Each page request fetches records sequentially from the last retrieved cursor, effectively creating a moving window of data.

SELECT * FROM Orders WHERE order_id > last_seen_order_id ORDER BY order_id ASC LIMIT 10;

In this example, last_seen_order_id represents the cursor, which is the ID of the last order fetched in the previous page request. This query ensures that the next set of results starts right after the last record of the previous set, providing a seamless transition through data.

Advantages of Cursor-Based Pagination​

  1. Performance Stability: Cursor-based pagination provides consistent load times regardless of the dataset's size. It eliminates the performance degradation associated with offset pagination, which increases as the offset value grows.
  2. Data Integrity: Since pagination is based on record values (e.g., ID or timestamp), adding or removing records doesn't affect the integrity of the paginated list. Users won't see duplicates or miss records as they navigate through pages.
  3. Efficient for Real-Time Data: This method is particularly effective for real-time data feeds, such as social media timelines or live transaction logs, where new data is continually added.

Platforms like Twitter and Facebook use cursor-based pagination to handle real-time updates in user feeds efficiently.

Disadvantages of Cursor-Based Pagination​

  1. Limited Navigation Flexibility: Unlike offset pagination, cursor-based pagination does not allow users to jump to a specific page since the cursor requires a sequential path through the dataset.
  2. Complexity in Implementation: Implementing cursor-based pagination can be more complex, particularly when dealing with multiple sorting orders or when the cursor column does not have a straightforward ordering.

Conclusion​

Cursor-based pagination offers a robust solution for managing large datasets, particularly where data integrity and performance consistency are crucial. While it lacks the direct page access provided by offset pagination, its advantages make it ideal for applications that require efficient and reliable data traversal. By understanding the strengths and limitations of cursor-based pagination, developers can better design systems that handle data-intensive operations effectively.