tursodatabase/turso · error

OpenRead on sorter cursor

Error message

OpenRead on sorter cursor

What it means

Insn::OpenRead executed on a cursor whose type is CursorType::Sorter. Sorter cursors are ephemeral row stores filled by SorterInsert for ORDER BY / GROUP BY / DISTINCT processing and are never backed by a database B-tree, so OpenRead is meaningless on them. The bytecode program used a sorter cursor id where a B-tree cursor was intended — a codegen inconsistency, panicked inside op_open_read.

Source

Thrown at core/vdbe/execute.rs:1451

                num_columns,
            )?;
            let index_info = Arc::new(if let Some(mv_store) = mv_store.as_ref() {
                IndexInfo::new_from_index_in(index, mv_store.allocator())?
            } else {
                IndexInfo::new_from_index(index)?
            });
            let cursor =
                maybe_promote_to_mvcc_cursor(btree_cursor, MvccCursorType::Index(index_info))?;
            cursors
                .get_mut(*cursor_id)
                .expect("cursor_id should be valid")
                .replace(cursor.into_cursor());
        }
        CursorType::Pseudo(_) => {
            panic!("OpenRead on pseudo cursor");
        }
        CursorType::Sorter => {
            panic!("OpenRead on sorter cursor");
        }
        CursorType::IndexMethod(..) => {
            unreachable!("IndexMethod handled above")
        }
        CursorType::VirtualTable(_) => {
            panic!("OpenRead on virtual table cursor, use Insn:VOpen instead");
        }
    }
    state.pc += 1;
    Ok(InsnFunctionStepResult::Step)
}

pub fn op_vopen(
    program: &Program,
    state: &mut ProgramState,
    insn: &Insn,
    _pager: &Arc<Pager>,
) -> InsnResult {

View on GitHub (pinned to 492c4a71cd)

Solutions

1. Report the SQL — the sorter cursor id must not flow into an OpenRead emission
2. Confirm the trigger by removing ORDER BY / DISTINCT and re-running; then attach both plans to the bug
3. Rewrite the query to sort in an outer query level so sorter and table cursors do not mix
4. Upgrade

// reuse the program audit: flag OpenRead against sorter cursors before execution
for insn in &program.insns {
    if let Insn::OpenRead { cursor_id, .. } = insn {
        if matches!(program.cursor_ref.get(*cursor_id).map(|(_, t)| t), Some(CursorType::Sorter)) {
            crate::bail_parse_error!("OpenRead targets sorter cursor");
        }
    }
}

When it happens

Trigger: ORDER BY / GROUP BY / DISTINCT queries whose sorter cursor id is reused or mis-resolved by a later OpenRead emission; cursor renumbering changes; scalar subqueries inside sorted outer queries where sorter and table cursor ids cross.

Common situations: Queries combining ORDER BY or DISTINCT with joins/subqueries; engine upgrades or planner changes that reallocated sorter cursor ids.

Related errors

• OpenRead on pseudo cursor
• Rewind on non-btree/materialized-view cursor
• unexpected cursor type
• Next on non-btree/materialized-view cursor
• {} on unexpected cursor

AI-assisted analysis of tursodatabase/turso@492c4a71cd (2026-08-20). Data as JSON: /api/errors/66fe727752415292. Report an issue: GitHub.