Relational Operator - Join in Calcite.
Join is a calcite relational operator (RelNode)
Example field addressing in a join between the input EMP and DEPT
join
/ \
EMP DEPT
The ordinal referencing is:
To reference the field/column SAL (the field 5 of input 0)
builder.field(2, 0, "SAL")
// or
builder.field(2, "EMP", "SAL")
// or
builder.field(2, 0, 5)
where: