On Sat, 26 Dec 2009 10:43:55 +0800 Eva said:
> 2009-12-26 2:36, Don Read :
>
> >
> > Change noticed to enum('new', 'scan', 'done') not null default 'new';
> >
> > When proc two runs, it should
> > "UPDATE noticed='scan' WHERE noticed='new'"
> > Then repeat the scan with "SELECT ... WHERE noticed='scan'"
> > ...
> > and finally it should "UPDATE domain=whatever, ... noticed='done'"
> >
>
> Thanks Don.
> That means, when process one want to update "ip" but it see
> noticed="scan", it will block until the status become "done", is it?
>
> Eva
Depends on how closely coupled the two processes are.
a. proc #1 can only insert new ip's (INSERT IGNORE)
b. proc #1 could ignore/refuse to update any ip not 'new'
c. proc #1 could leave the noticed field alone.
d. proc #1 could set noticed to 'new' (and let proc #2 scan it again)
Which alternative works best for your application?
Regards,
--
Don Read don_r...@att.net
It's always darkest before the dawn. So if you are going to
steal the neighbor's newspaper, that's the time to do it.
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