Lead/Lag function does not return default value for out of range offset

[xumingming]

// Trino TestLeadFunction.java
assertWindowQuery("lead(orderkey, null, -1) OVER (PARTITION BY orderstatus ORDER BY orderkey)",
        resultBuilder(TEST_SESSION, INTEGER, VARCHAR, INTEGER)
                .row(3, "F", null)
                .row(5, "F", null)
                .row(6, "F", null)
                .row(33, "F", null)
                .row(1, "O", null)
                .row(2, "O", null)
                .row(4, "O", null)
                .row(7, "O", null)
                .row(32, "O", null)
                .row(34, "O", null)
                .build());

In this test case, the offset is null, default value is specified as -1, but the expected value is null rather than -1, while in the doc([1]), it says that default value should be returned:

If the offset is null or larger than the window, the default_value is returned, or if it is not specified null is returned.

Lag function has similar issue.

[1]. https://trino.io/docs/current/functions/window.html

[xumingming]

Related discussion in Velox: facebookincubator/velox#6413

[martint]

The proper behavior is to raise an error if the offset is null, per the SQL specification.