[CALCITE-2838] Simplification: Remove redundant IS TRUE checks

• Type: Improvement
• Status: Closed
• Priority: Blocker
• Resolution: Fixed
• Fix Version/s: 1.19.0
• Labels: pull-request-available
• Assignee: Zoltan Haindrich
• Reporter: Zoltan Haindrich
• Created: 11/Feb/19 07:32
• Updated: 25/Mar/19 00:11
• Resolved: 23/Feb/19 16:22

Description

In case simplifcation is already processing in unknownAsFalse mode, expr IS TRUE is redundant - and may just prevent further optimizations from happening:

  @Test public void testRedundantIsTrue() {
    // in case of unknownAsFalse
    // x is TRUE <=> x
    checkSimplify3(isTrue(vBool(1)),
        "IS TRUE(?0.bool1)",
        "?0.bool1",
        "IS TRUE(?0.bool1)");
  }

there are some further possibilities

(unknownAsTrue) x is NOT FALSE <=> x
(unknownAsTrue) x is FALSE <=> not x

Issue Links

• relates to: CALCITE-2932 DruidAdapterIT regression after 1.17 release
• links to: GitHub Pull Request #1044