get_attavgwidth_hook

中文定义与说明

供插件在 get_attavgwidth() 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 int32 (*get_attavgwidth_hook_type) (Oid relid, AttrNumber attnum);
extern PGDLLIMPORT get_attavgwidth_hook_type get_attavgwidth_hook;

调用位置

• src/backend/utils/cache/lsyscache.c:3467

核心调用上下文：src/backend/utils/cache/lsyscache.c:3461–3475

{
	HeapTuple	tp;
	int32		stawidth;

	if (get_attavgwidth_hook)
	{
		stawidth = (*get_attavgwidth_hook) (relid, attnum);
		if (stawidth > 0)
			return stawidth;
	}
	tp = SearchSysCache3(STATRELATTINH,
						 ObjectIdGetDatum(relid),
						 Int16GetDatum(attnum),
						 BoolGetDatum(false));
	if (HeapTupleIsValid(tp))