Function FetchPreparedStatement

src/backend/commands/prepare.c:490–514

* Lookup an existing query in the hash table. If the query does not * actually exist, throw ereport(ERROR) or return NULL per second parameter. * * Note: this does not force the referenced plancache entry to be valid, * since not all callers care. */

 * since not all callers care.
 */
PreparedStatement *
FetchPreparedStatement(const char *stmt_name, bool throwError)
{
	PreparedStatement *entry;

	/*
	 * If the hash table hasn't been initialized, it can't be storing
	 * anything, therefore it couldn't possibly store our plan.
	 */
	if (prepared_queries)
		entry = (PreparedStatement *) hash_search(prepared_queries,
												  stmt_name,
												  HASH_FIND,
												  NULL);
	else
		entry = NULL;

	if (!entry && throwError)
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_PSTATEMENT),
				 errmsg("prepared statement \"%s\" does not exist",
						stmt_name)));

	return entry;
}

/*
 * Given a prepared statement, determine the result tupledesc it will