Calcite - Join

About

Relational Operator - Join in Calcite.

Join is a calcite relational operator (RelNode)

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Field Addressing

Example field addressing in a join between the input EMP and DEPT

join       
  /   \      
EMP   DEPT

The ordinal referencing is:

• 0=EMP
  • 0=EMPNO,
  • 1=ENAME,
  • 2=JOB,
  • 3=MGR,
  • 4=HIREDATE,
  • 5=SAL,
  • 6=COMM,
  • 7=DEPTNO]
• 1=DEPT
  • 0=DEPTNO,
  • 1=DNAME,
  • 2=LOC

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:

• 2 means that there are two inputs (How deep to search in the stack)
• 0 or EMP design the input
• 5 or SAL design the field