《Valid OUTER JOIN OptimizationsOUTER JOIN 优化手段 The planner’s treatment of outer join reordering is based on the followingidentities:规划器基于以下恒等式处理外连接: 1. (A leftjoin B on (Pab)) innerjoin C on (Pac) 》>>>PostgreSQL 源码解读（208）- 查询#121(Valid OUTER JOIN Optimizations)