[IMPALA-5211] Simplify remaining constant conditionals

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 2.10.0
• Fix Version/s: Impala 2.11.0
• Component/s: Frontend
• Labels: newbie performance
• Epic Color: ghx-label-3
• Assignee: Philip Martin
• Reporter: Thomas Tauber-Marshall
• Created: 17/Apr/17 15:26
• Updated: 18/Sep/17 22:31
• Resolved: 18/Sep/17 22:31

Description

A recent change (IMPALA-1861) added SimplifyConditionalsRule which simplifies some conditional functions with constant conditions (e.g. if (true, 0, 1) -> 0).

This rule currently only covers IF, OR, AND, CASE, and DECODE. We should extend it to cover further conditionals, such as COALESCE, IFNULL, IS(TRUE/FALSE), etc.