[drupal-support] How to use MySQL last_insert_id function with locking?

[Chris Johnson]

KZ Mai wrote:
> Hi,
> I am developing my own module which uses tables that have auto-increment fields.
> 
> As far as I can tell, drupal uses a single connection for my default
> configuration.
> 
> I don't think i think use last_insert_id without locking because the
> MySQL DB connection is shared accross requests.
> 
> so what should I lock in order to get the correct result from last_insert_id?

I'm not positive I understand what you are asking, but Drupal's use of a 
single database connection does not preclude you from using last_insert_id(). 
  Each thread or process of your web server will have its own copy of the 
database connection used by Drupal, and MySQL will properly keep track of the 
last ID used in an auto_increment field for each connection.  Even if the 
thread running your code is interrupted by the operating system between the 
insert and your call to last_insert_id(), no other thread will use that 
connection and that information in last_insert_id() will remain valid when 
your thread is resumed.

--
Chris Johnson