Keyset Pagination vs. OFFSET in SQL Server: A More Efficient Approach?

A more efficient solution for SQL Server paging: Keyset paging

In SQL Server, paging is usually implemented using OFFSET, but for large tables, Keyset paging is a more efficient method. Unlike rowset pagination, which requires reading all previous rows to reach the desired page, Keyset pagination jumps directly to the correct location in the index, significantly improving performance.

Implementing Keyset paging requires building a unique index on the required key. The key can contain additional columns required by the query. It should be noted that this method cannot directly jump to a specific page number. Instead, you need to locate a specific key first and then move on from there.

One advantage of Keyset paging is that it avoids the "lost row" problem caused by deleting rows in rowset paging. Since paging is based on keys, changes in the order of rows will not affect the paging logic.

The following is an example of using Keyset pagination in SQL Server:

<code class="language-sql">SELECT TOP (@numRows)
  *
FROM TableName
ORDER BY Id DESC;</code>

This query retrieves the first page of data in descending order by the Id column. To paginate further, you can use the last received Id value like this:

<code class="language-sql">SELECT TOP (@numRows)
  *
FROM TableName
WHERE Id < @lastId
ORDER BY Id DESC;</code>

To support paging by non-unique columns, additional columns must be included in both the ORDER BY and WHERE clauses. Appropriate indexes need to be built on selected columns to ensure efficient execution.

Keyset paging provides a more efficient alternative to OFFSET paging for large data sets in SQL Server. It avoids unnecessary row reads and ensures consistent paginated results even when data is modified.

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