[CALCITE-55] Don't create sets that are just a column-permutation of an existing set

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Labels: github-import
• Assignee: Unassigned
• Reporter: GitHub Import
• Created: 18/Jun/14 07:56
• Updated: 09/Mar/21 22:16

Description

Don't create sets that are just a column-permutation of an existing set. For example, if setX has columns [c0, c1, c2, c3] and the the expression 'Project(setX, c2, c3, c1, c0)' is registered, don't create a new setY.

This change would reduce the number of almost-identical sets and reduce the number of rules that need to fire.

I'm not sure whether it's possible to put 'Project(setX, c0, c1)', which has a subset of columns, in setX.

---------------- Imported from GitHub ----------------
Url: https://github.com/julianhyde/optiq/issues/55
Created by: julianhyde
Labels:
Created at: Fri Sep 27 01:14:50 CEST 2013
State: open

Issue Links

• relates to: CALCITE-62 Allow a RelNode in a RelSet to return columns in permuted order