摘要：
对Join的成本计算的调用路径：make_one_rel ->make_rel_from_joinlist ->standard_join_search -> join_search_one_level -> make_join_rel -> add_paths_to_joinrel ->hash_inner_and_outer ->try_hashjoin_path ->initial_cost_hashjoin在make_join_rel函... 阅读全文
摘要：
开始用 explain来看hash join:postgres=# explain select dept.no_emps,emp.age from dept,emp where emp.name = dept.mgr and dept.dept_name = 'shoe'; QUERY PLAN ------------------------------------------------------------------ Hash Join (cost=19.30..45.07... 阅读全文