Hi Kyle,
On 20/6/10, Kyle Sluder wrote:
to temporarily hide sales that are in progress on other machines.
I currently do that but in a more awkward way,
Might you instead want to make a sale an atomic thing? Perform the
sale on a scratch MOC, and then when the sale is complete (or voided),
merge the scratch MOC into the main MOC.
That's a good idea. I do that to a small degree when the sale is
first created, so I can "micro-save" it. After that there are
so many relationships from the other MOC: products, bikes,
customer, employee... that I had felt it might be troublesome.
I'm rethinking that.
But that aside, I do actually save in-progress sales during idle
time to update the inventory levels so, for example, a bike
doesn't get sold twice. Once saved, I need to 'hide' the Sale
from other machines.
Also, this seems to imply that you're sharing the same persistent
store amongst all your clients. This way lies madness.
The madness had its four-year anniversary this very day :)
Each machine runs idle-time code which ensures it has recent
data from the shared store. It was hard to get right but after
a year of tweaking, it works well. SQLite has just enough
locking capability to make it work.
The shared store is on a Synology NAS that claims to be able to
saturate gigabit ethernet. Its really fast. It has a 128-meg
cache and our database is only 30 meg. Flies. Does complex
queries and returns the results often in under 5 msec. I've
seen 1 msec.
Others have described theoretical alternatives but they don't
sound inviting at all and I haven't seen any sample code. A
friend gave me a book with a complex alternative which looks
complete, at least. Some day, maybe,
I have an irrational hope that Apple will, one day, add another
back-end option to Core Data.
All that said, I'm all ears to simple, practical, proven,
scalable alternatives with sample code.
Cheers,
Steve
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