[sr-dev] git:master: acc: extended documentation for db_insert_mode parameter

[Juha Heinanen]

Daniel-Constantin Mierla writes:

> >>      Default value is 0 (no INSERT DELAYED).
> > daniel,
> >
> > just to clarity, is there some relationship between INSERT DELAYED and
> > async insert?
> No.

good.  so perhaps the comment on default value could be (no INSERT
DELAYED nor async insert is used).

> The mechanism behind async insert is as follow:
> - the INSERT query is printed by the process that does the db operation
> - the mysql module instead of sending the query to mysql server, clones 
> it in shared memory and sends it to the group of async workers
> - one of the workers reads the task and sends the query to the database 
> server

does there need to be a free async worker to serve the request or are
the requests buffered so that the sender of the request is always
immediately free to go on with other business?

> To have the above working, the db_url is also cloned and sent to async 
> workers in order to identify the right connection to use. The first idle 
> async worker is receiving the task (it is kernel based, the same 
> mechanism used for many processes reading on the same UDP socket). You 
> have to specify the number of async workers via global parameter 
> async_workers:
> 
> - http://www.kamailio.org/wiki/cookbooks/devel/core#async_workers

that would have been my next question.  if someone only reads
acc/README, it does not mention a need set async_workers > 0 in order to
benefit from db_insert_mode=2.

-- juha