Hi Community, Module `shardingsphere-query-optimizer` is designed to process SQL Query Optimizer. I prefer use Apache Calcite to recognize SQL like subquery, join query cross actual databases, etc. which couldn't execute to databases directly. Common optimization rules include Predicate Pushdown, Constant Folding, and Column Pruning etc. which have implementation in HepPlanner and VolcanoPlanner of Calcite. In my opinion, `shardingsphere-query-optimizer` module could be one of task topics for 'Open Source Promotion Plan - Summer 2020', which includes tasks for reuse optimization rules of HepPlanner and VolcanoPlanner to optimize partial SQL in ShardingSphere for performance improvement. Through previous experience using Calcite with Flink SQL, I'd like to support `shardingsphere-query-optimizer` module, welcome anyone to work on this module together.
Thanks, Nicholas Jiang
