[CALCITE-1883] HepPlanner should force garbage collect whenever a root registered

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.14.0
• Assignee: Julian Hyde
• Reporter: Ted Xu
• Created: 10/Jul/17 12:44
• Updated: 02/Oct/17 14:31
• Resolved: 18/Jul/17 17:59

Description

Currently HepPlanner#collectGarbage() will skip if there is no new transform since last GC. If HepPlanner is reused, it is common case that no transform is applied after last cheapest plan is built while before next round of optimize is kicked off.

This may break HepPlanner because the garbage is probably not a graph after HepPlanner#buildFinalPlan .

I'll try if I can create a reproduce case.