[CALCITE-1058] Add method RelBuilder.empty, and rewrite LIMIT 0 to it

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.6.0
• Assignee: Julian Hyde
• Reporter: Julian Hyde
• Created: 14/Jan/16 05:37
• Updated: 02/Feb/16 19:08
• Resolved: 14/Jan/16 23:21

Description

Add a method RelBuilder.empty(), a new method that returns an empty relation. The default implementation returns a Values with no rows, but schema-on-query systems such as Drill might override the empty method to read schema from an input at query time.

RelBuilder.filter(false) and RelBuilder.limit(0, 0) should simplify to empty().

Issue Links

• relates to: HIVE-12839 Upgrade Hive to Calcite 1.6