get_relation_stats_hook

中文定义与说明

供插件在请求统计信息时接管处理的钩子。

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 bool (*get_relation_stats_hook_type) (PlannerInfo *root, RangeTblEntry *rte, AttrNumber attnum, VariableStatData *vardata);
extern PGDLLIMPORT get_relation_stats_hook_type get_relation_stats_hook;

调用位置

• src/backend/utils/adt/selfuncs.c:5717
• src/backend/utils/adt/selfuncs.c:6198
• src/backend/utils/adt/selfuncs.c:8752

核心调用上下文：src/backend/utils/adt/selfuncs.c:5711–5725

{
	RangeTblEntry *rte = root->simple_rte_array[var->varno];

	Assert(IsA(rte, RangeTblEntry));

	if (get_relation_stats_hook &&
		(*get_relation_stats_hook) (root, rte, var->varattno, vardata))
	{
		/*
		 * The hook took control of acquiring a stats tuple.  If it did supply
		 * a tuple, it'd better have supplied a freefunc.
		 */
		if (HeapTupleIsValid(vardata->statsTuple) &&
			!vardata->freefunc)
			elog(ERROR, "no function provided to release variable stats with");

核心调用上下文：src/backend/utils/adt/selfuncs.c:6192–6206

		relid = rte->relid;
		Assert(relid != InvalidOid);
		colnum = index->indexkeys[indexcol];
		vardata->rel = index->rel;

		if (get_relation_stats_hook &&
			(*get_relation_stats_hook) (root, rte, colnum, vardata))
		{
			/*
			 * The hook took control of acquiring a stats tuple.  If it did
			 * supply a tuple, it'd better have supplied a freefunc.
			 */
			if (HeapTupleIsValid(vardata->statsTuple) &&
				!vardata->freefunc)
				elog(ERROR, "no function provided to release variable stats with");

核心调用上下文：src/backend/utils/adt/selfuncs.c:8746–8760

		/* attempt to lookup stats in relation for this index column */
		if (attnum != 0)
		{
			/* Simple variable -- look to stats for the underlying table */
			if (get_relation_stats_hook &&
				(*get_relation_stats_hook) (root, rte, attnum, &vardata))
			{
				/*
				 * The hook took control of acquiring a stats tuple.  If it
				 * did supply a tuple, it'd better have supplied a freefunc.
				 */
				if (HeapTupleIsValid(vardata.statsTuple) && !vardata.freefunc)
					elog(ERROR,
						 "no function provided to release variable stats with");