Comment by danneu

The downside is that OFFSET is slow if you have a lot of items, like on a forum.

At which point you could assign each post in a topic an indexed `position` column that always increases from 0 within that topic, which lets you jump to arbitrary pages and parameterize perPage.

    fromPos = (page - 1) * perPage
    
    SELECT *
    FROM posts
    WHERE topic_id = $1
      AND position >= fromPos
      AND position < fromPos + perPage
    ORDER BY id

For simpler needs, your "Next" button could load items that come after the last ID on the current page but with a LIMIT.

    <ul>
      {% for item in items %}
        <li>{{ item }}</li>
      {% endfor %}
    </ul>

    <a href="/items?afterId={{ items[items.length - 1].id }}">Next</a>

    SELECT *
    FROM items
    WHERE id > $afterId
    LIMIT $perPage

That's fast and really easy.