create_upper_paths_hook

中文定义与说明

供插件在 grouping_planner() 规划上层关系时接管处理的钩子。

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 (*create_upper_paths_hook_type) (PlannerInfo *root, UpperRelationKind stage, RelOptInfo *input_rel, RelOptInfo *output_rel, void *extra);
extern PGDLLIMPORT create_upper_paths_hook_type create_upper_paths_hook;

源码说明

允许扩展添加更多路径。

允许扩展添加更多部分路径。

调用位置

• src/backend/optimizer/plan/planner.c:2386
• src/backend/optimizer/plan/planner.c:4379
• src/backend/optimizer/plan/planner.c:4819
• src/backend/optimizer/plan/planner.c:5062
• src/backend/optimizer/plan/planner.c:5237
• src/backend/optimizer/plan/planner.c:5707

核心调用上下文：src/backend/optimizer/plan/planner.c:2380–2394

		final_rel->fdwroutine->GetForeignUpperPaths(root, UPPERREL_FINAL,
													current_rel, final_rel,
													&extra);

	/* Let extensions possibly add some more paths */
	if (create_upper_paths_hook)
		(*create_upper_paths_hook) (root, UPPERREL_FINAL,
									current_rel, final_rel, &extra);

	/* Note: currently, we leave it to callers to do set_cheapest() */
}

/*
 * Do preprocessing for groupingSets clause and related data.
 *

核心调用上下文：src/backend/optimizer/plan/planner.c:4373–4387

		grouped_rel->fdwroutine->GetForeignUpperPaths(root, UPPERREL_GROUP_AGG,
													  input_rel, grouped_rel,
													  extra);

	/* Let extensions possibly add some more paths */
	if (create_upper_paths_hook)
		(*create_upper_paths_hook) (root, UPPERREL_GROUP_AGG,
									input_rel, grouped_rel,
									extra);
}

/*
 * For a given input path, consider the possible ways of doing grouping sets on
 * it, by combinations of hashing and sorting.  This can be called multiple
 * times, so it's important that it not scribble on input.  No result is

核心调用上下文：src/backend/optimizer/plan/planner.c:4813–4827

		window_rel->fdwroutine->GetForeignUpperPaths(root, UPPERREL_WINDOW,
													 input_rel, window_rel,
													 NULL);

	/* Let extensions possibly add some more paths */
	if (create_upper_paths_hook)
		(*create_upper_paths_hook) (root, UPPERREL_WINDOW,
									input_rel, window_rel, NULL);

	/* Now choose the best path(s) */
	set_cheapest(window_rel);

	return window_rel;
}