[CALCITE-1977] Use Cosette to check whether planner rules are valid

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Assignee: Unassigned
• Reporter: Julian Hyde
• Created: 08/Sep/17 21:25
• Updated: 30/Jul/21 03:51

Description

Use Cosette, an automated SQL solver from University of Washington, to check whether planner rules are valid.

I don't know whether Cosette is written in Java, so the simplest approach might be to instrument the planner to generate a script. Suppose FilterProjectTransposeRule has just fired successfully. Then RelOptRuleCall#transformTo would generate the line

  assertEquivalent(
    "select * from (select empno from emp) where empno > 10",
    "select empno from (select * from emp where empno > 10)")

(Those SQL statements are the result of converting the before and after RelNode instances to SQL.)

We could run the Calcite test suite to produce a large script with probably thousands of those statements. Then the Cosette researchers can take that script and run it through Cosette (using whatever language they develop in). It would find bugs in Cosette (at first mostly deficiencies in Cosette's SQL parser, I fear) but also would find bugs in Calcite if the transformation is not valid. (Not too many, I hope!)