健哥的数据花园

摘要： 继续分析 query_planner：/* * query_planner * Generate a path (that is, a simplified plan) for a basic query, * which may involve joins but not any fancier features. * * Since query_planner does not handle the toplevel processing (grouping, * sorting, etc) it cannot select the best path by itsel... 阅读全文

摘要： 接前面： Query *parse = root->parse; List *tlist = parse->targetList; int64 offset_est = 0; int64 count_est = 0; double limit_tuples = -1.0; Plan *result_plan; List *current_pathkeys; double dNumGroups = 0; bool use_ha... 阅读全文

摘要： 接前面，继续对 subquery_planner来分析：下面这一段都是对 表达式进行处理的，对我的简单查询，可以忽略。 /* * Do expression preprocessing on targetlist and quals, as well as other * random expressions in the querytree. Note that we do not need to * handle sort/group expressions explicitly, because they are actually * part o... 阅读全文