{"id":"btree-leaf-sibling-chain-forward-only","text":"Leaf pages store a `next_sibling` forward pointer (`NO_SIBLING = 0xFFFFFFFF` sentinel) but no backward pointer, so unlinking a leaf from the sibling chain requires locating the predecessor via parent traversal rather than direct backlink.","truth_value":"IN","source":"entries/2026/05/29/topic-postgres-nbtree-vacuum.md","source_url":"","source_hash":"","justifications":[],"dependents":["btree-traversal-is-forward-only"],"metadata":{},"created_at":"","updated_at":"","reviewed_at":"","verified_at":"","retracted_at":"","explanation":{"steps":[{"node":"btree-leaf-sibling-chain-forward-only","truth_value":"IN","reason":"premise"}]}}