[FLINK-3944] Add optimization rules to reorder Cartesian products and joins

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Won't Fix
• Affects Version/s: 1.1.0
• Fix Version/s: 1.1.0
• Component/s: Table SQL / API
• Assignee: Fabian Hueske
• Reporter: Fabian Hueske
• Created: 20/May/16 12:59
• Updated: 14/Jun/16 16:27
• Resolved: 14/Jun/16 16:27

Description

Currently, we do not support the execution of Cartesian products.
Because we do not optimize the order of joins (due to missing statistics), joins are executed in the order in which they are specified. This works well for the Table API, however it can be problematic in case of SQL queries where the order of tables in the FROM clause should not matter.

In case of SQL queries, it can happen that the optimized plan contains Cartesian products because joins are not reordered. If we add optimization rules that switch Cartesian products and joins, such situations can be resolved.

Issue Links

• links to: GitHub Pull Request #2044
• links to: GitHub Pull Request #2098