Function SaveCachedPlan

src/backend/utils/cache/plancache.c:461–495

* SaveCachedPlan: save a cached plan permanently * * This function moves the cached plan underneath CacheMemoryContext (making * it live for the life of the backend, unless explicitly dropped), and adds * it to the list of cached plans that are checked for invalidation when an * sinval event occurs. * * This is guaranteed not to throw error, except for the caller-error case * of trying to

 * automatically on transaction abort.
 */
void
SaveCachedPlan(CachedPlanSource *plansource)
{
	/* Assert caller is doing things in a sane order */
	Assert(plansource->magic == CACHEDPLANSOURCE_MAGIC);
	Assert(plansource->is_complete);
	Assert(!plansource->is_saved);

	/* This seems worth a real test, though */
	if (plansource->is_oneshot)
		elog(ERROR, "cannot save one-shot cached plan");

	/*
	 * In typical use, this function would be called before generating any
	 * plans from the CachedPlanSource.  If there is a generic plan, moving it
	 * into CacheMemoryContext would be pretty risky since it's unclear
	 * whether the caller has taken suitable care with making references
	 * long-lived.  Best thing to do seems to be to discard the plan.
	 */
	ReleaseGenericPlan(plansource);

	/*
	 * Reparent the source memory context under CacheMemoryContext so that it
	 * will live indefinitely.  The query_context follows along since it's
	 * already a child of the other one.
	 */
	MemoryContextSetParent(plansource->context, CacheMemoryContext);

	/*
	 * Add the entry to the global list of cached plans.
	 */
	dlist_push_tail(&saved_plan_list, &plansource->node);

	plansource->is_saved = true;
}

/*
 * DropCachedPlan: destroy a cached plan.