[CALCITE-41] Add rule to propagate constraints onto aliased columns

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Duplicate
• Fix Version/s: 0.9.0-incubating
• Labels: github-import
• Assignee: Julian Hyde
• Reporter: GitHub Import
• Created: 18/Jun/14 07:52
• Updated: 19/Dec/14 18:35
• Resolved: 19/Dec/14 18:27

Description

Consider:

SELECT *
FROM emp JOIN dept ON emp.deptno = dept.deptno
WHERE emp.deptno = 10

Clearly we can push down "emp.deptno = 10" through the join. But we can also generate a constraint "dept.deptno = 10" on the other input to the join. This task is to add a rule to achieve that.

The rule would propagate the constraints on column "a" onto column "b" when "a" and "b" are compared using "=" or other relational operator (e.g. ">") in a filter or join condition.

The planner state should reflect the fact that such constraints are optional – i.e. the query produces the same result if the constraints are omitted – and therefore the constraints can be omitted if they turn out to be expensive to implement.

---------------- Imported from GitHub ----------------
Url: https://github.com/julianhyde/optiq/issues/41
Created by: julianhyde
Labels:
Created at: Fri May 17 01:13:26 CEST 2013
State: open

Issue Links

• duplicates: CALCITE-360 Introduce a Rule to infer predicates from equi join conditions.