Right-link (B-tree)
Also called: right sibling pointer, btpo_next, B-link pointer
Each B-tree page stores a pointer to its right sibling at the same level (the btpo_next field). These pointers chain every page on a level into a left-to-right list. A search that discovers its key has moved (via the high key) follows the right-link to find it, rather than going back up to the root.
What this means
Each B-tree page holds a pointer to its right-hand neighbor on the same level, chaining every page on that level into a left-to-right list. If a search finds its key has slid onto the next page (via the high key), it just follows this link sideways instead of climbing back up to the root.
Why it matters operationally
The right-link is the heart of the Lehman-Yao "B-link" design. Because a split links the new page into the sibling chain before it updates the parent, readers can always reach a freshly split page through the right-link, which is why index reads almost never block on concurrent inserts.