btree-put-is-upsert

Status: IN

`BTree.put()` on an existing key updates the value in-place without incrementing `len(tree)` — it is an upsert, not a blind insert.

Source: entries/2026/05/28/b-tree-storage-engine-tester_test_btree.md

Example

# _insert into leaf: if key exists, update value; else insert new
idx = bisect_left(keys, key)
if idx < len(keys) and keys[idx] == key:
    values[idx] = value  # update
else:
    keys.insert(idx, key); values.insert(idx, value)  # insert

JSON