set_join_pathlist_hook

中文定义与说明

供插件在 add_paths_to_joinrel() 中接管处理的钩子。

以下中文为本站依据所列 PostgreSQL 源码注释编译的说明。

接口声明

typedef void (*set_join_pathlist_hook_type) (PlannerInfo *root, RelOptInfo *joinrel, RelOptInfo *outerrel, RelOptInfo *innerrel, JoinType jointype, JoinPathExtraData *extra);
extern PGDLLIMPORT set_join_pathlist_hook_type set_join_pathlist_hook;

源码说明

6. 最后，允许扩展调整路径列表。扩展可调用 add_path() 添加新路径（例如 CustomPaths）；若支持并行，则可调用 add_partial_path()。也可以删除或修改核心代码添加的路径。

调用位置

• src/backend/optimizer/path/joinpath.c:343

核心调用上下文：src/backend/optimizer/path/joinpath.c:337–351

	 * 6. Finally, give extensions a chance to manipulate the path list.  They
	 * could add new paths (such as CustomPaths) by calling add_path(), or
	 * add_partial_path() if parallel aware.  They could also delete or modify
	 * paths added by the core code.
	 */
	if (set_join_pathlist_hook)
		set_join_pathlist_hook(root, joinrel, outerrel, innerrel,
							   jointype, &extra);
}

/*
 * We override the param_source_rels heuristic to accept nestloop paths in
 * which the outer rel satisfies some but not all of the inner path's
 * parameterization.  This is necessary to get good plans for star-schema
 * scenarios, in which a parameterized path for a large table may require