[CALCITE-4383] In RelBuilder, optimize Union(all, Values, Values) to Values

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.27.0
• Assignee: Julian Hyde
• Reporter: Julian Hyde
• Created: 07/Nov/20 07:26
• Updated: 03/Jun/21 22:32
• Resolved: 13/Nov/20 05:57

Description

In RelBuilder, optimize Union(all, Values, Values) to Values. Similarly optimize Project(Values) to Values if the projected expressions are all literals.

This pattern occurs frequently, if someone writes SELECT 1, 'a' UNION ALL SELECT 2, 'b' for instance.

Enable this rewrite with a new property boolean RelBuilder.Config.simplifyValues(), default true.