Functions are ways to transform one set of data into another. They are defined in modules and are part of the database schema.
For example, consider the function
len()
used to transform a set of str
into a set
of int64
:
db>
SELECT len({'hello', 'world'});
{5, 5}
Compare that with the aggregate
function count()
that transforms a set of str
into a single int64
value, representing the set
cardinality:
db>
SELECT count({'hello', 'world'});
{2}
Function SDL, DDL, and introspection.