@terascope/data-mate / teal-frame/order-safety

teal-frame/order-safety

Functions

assertOrderSafe()

assertOrderSafe(operation, ordered): void

Defined in: data-mate/src/teal-frame/order-safety.ts:14

Throws if an operation would silently discard the frame's ordering. Used by TealFrame's join, distinct and aggregating select.

SQL does not guarantee that a subquery's ORDER BY survives the outer query. In DuckDB a projection, WHERE, LIMIT or OFFSET keeps the order, but a hash join or hash aggregate reorders rows. This only shows once the data is large enough to run in parallel (small inputs come out ordered), so it is easy to miss in tests. Sort the result instead.

A global aggregate written directly into select's expressions with no groupBy ({ total: 'sum(x)' }) is not detected, because the expressions are raw SQL. It returns one row, so the ordering does not matter.

Parameters

Parameter	Type
operation	string
ordered	boolean

Returns

void