MySQL SELECT ... FOR SHARE 会不会分配事务id ?

[kaiser20106]

已知
A transaction ID is only needed for a transaction that might perform write operations or locking reads such as SELECT ... FOR UPDATE.

START TRANSACTION;

SELECT * FROM table  -- trx_id 283911508463232
SELECT * FROM table  for share -- 283911508463232
SELECT * FROM table  for update -- 93004
-- 查询当前会话是否存在活跃事务
SELECT * FROM information_schema.innodb_trx WHERE trx_mysql_thread_id = CONNECTION_ID();

加了for share 跟普通select trx_id一样，如果说不分配事务id，那上面的mysql原文怎么理解，locking reads包括for share和 FOR UPDATE啊