CTDB API
tridge at samba.org
tridge at samba.org
Mon Oct 30 23:24:45 GMT 2006
Volker,
> This logic (essentially the share_mode_conflict loop) has to
> be coded in the DMASTER, and it needs to be aware about the
> DB semantics. Not nice and clean, but fast :-)
yep. It's not just the round trip saving that is key to this
though. It is the fact that a a record is never locked while waiting
for a network operation. That is really the key!
As soon as you have a record locked 'remotely' then you get all the
worst nasties of cluster computing coming to ensnare you. A delay on a
network link between nodes A and B suddenly becomes a problem for node
C, and you start getting feedback and a catastrophic slow down of the
entire system. You also open up the possibility of deadlocks.
That's why I'm really hoping that we can get rid of
CTDB_REQ_FETCH_LOCKED.
> P.S: We could encode the rules in Javascript in the DB or
> so....
>
> P.P.S: This was a JOKE! :-)
:-)
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