I think you must have made your modifications on an older version of SQLite. The btree "moveto" routines have now been split up into separate procedures for table-btrees and index-btrees (for better performance) and the index-btree version does not have an append-bias flag. See [check-in 3b0d34e5e5f9a16c][1] for the details of the change. [1]: https://www.sqlite.org/src/info/3b0d34e5e5f9a16c