Pagination is one of the hardest problems for web applications supporting access-control lists (ACLs). Drupal and Pressflow support ACLs through the node access system.
Problems with traditional pagination
- Because pagination uses row offsets into the results, browsing listings where newly published items get added to the beginning of the results creates “page drift.” Page drift is where a user already browsing through paginated results sees, for example, items E, D, and C on page one, waits awhile, clicks to the next page, and sees items C, B, and A. Going back to page one again shows F (newly published), E, and D. Item C “drifted” to page two while the user was reading page one. If new items are published frequently enough, pagination can become unusable due to this drifting effect.
- Even if content and ordering are fully indexed, jumping n rows into the results remains inefficient; it scales linearly with depth into pagination.
- Paginating sets where the content and ordering are not fully indexed is even worse, often to the point of being unusable.
- The design is optimized around visiting arbitrary page offsets, which does not reflect user needs. Users only need to make relative jumps in pagination of up to 10 pages (or so) in either direction or to start from the end of the results. (If users are navigating results by hopping to arbitrary pages to drill down to what they need, there are other flaws in the system.)
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