[CALCITE-2314] Verify RexNode transformations by evaluating before and after expressions against sample values

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.17.0
• Assignee: Julian Hyde
• Reporter: Julian Hyde
• Created: 16/May/18 20:32
• Updated: 20/Jul/18 08:18
• Resolved: 29/May/18 06:46

Description

Verify transformations of RexNode expressions (such as simplification, see class RexSimplify) by evaluating before and after expressions against sample values.

Given an expression, say ($0 < $1) IS NOT NULL we can bind $0 and $1 to values (0, 1, null) and evaluate the 9 combinations. We can also evaluate the simplified expression $0 IS NOT NULL AND $1 IS NOT NULL and see whether it gives the same value for each of the combinations.

We can add this checking to existing tests with little effort. It will improve confidence that we handle 3-valued logic correctly.

As part of this task, we will create an interpreter class RexInterpreter that evaluates RexNode expressions for common operators without generating code. It is not very efficient and does not cover very many types, functions and operators, but should be easy for people to extend to add a few more.

Issue Links

• is related to: CALCITE-2247 Simplify AND and OR conditions using predicates
• relates to: CALCITE-2332 Wrong simplification of FLOOR(CEIL(x)) to FLOOR(x)