A group, cumulative, or moving computation.
For Window Aggregate Function syntax, see Window Aggregate Functions.
In presence of ties in the sort key of the Window Aggregate Function syntax, FIRST_VALUE and LAST_VALUE are non-deterministic. They return value_expression from any one of the rows with tied order by value.
If the ROWS phrase is omitted and there is no ORDER BY phrase, the default ROWS is UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING.