[CALCITE-3049] When simplifying expressions, revisit "IS NULL" if its argument has been simplified

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.20.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Danny Chen
• Reporter: Julian Hyde
• Created: 04/May/19 22:21
• Updated: 24/Jun/19 15:02
• Resolved: 06/May/19 18:53

Description

When simplifying expressions, revisit "IS NULL" if its argument has been simplified. For example, we currently simplify

(CASE WHEN FALSE THEN +(v0) ELSE -1 END) IS UNKNOWN

to

-1 IS UNKNOWN

but we should further simplify that to FALSE.

I have a preliminary dev branch, but it needs a little more debugging. I'd be grateful if someone could finish it.

Issue Links

• links to: GitHub Pull Request #1198