John:
> master-master replication has all kinds of inherent issues if you're
> concerned with data and transactional integrity.
We have evaluated the problems and think we have found adequate
workarounds for them. The sites we deploy are e-commerce sites so:
1. There are a lot more reads than writes.
2. When we need to write to the database, it is saving
info for an order. All orders are independent
of each other so there is no conflict for those.
3. Product updates, fulfillments, etc. happen once
daily at night when the traffic is almost nonexistant.
The updates are sent to only one server so there is no
conflict there.
The only potential place a conflict may occur is in
the qty available for a specific product. The inventory
system updates the inventory regularly so even if the number
is wrong, it gets refreshed shortly thereafter.
We even built an application layer on top of master-master
replication to handle cases where a transaction fails.
We are using this system for several large clients
and it is working well. Being able to have geographical
redundancy at a reasonable cost (A true cluster would
be very high cost) outweighs the limitations.
Thanks,
Neil
--
Neil Aggarwal, (281)846-8957
MySQL pre-installed on a virtual private server for $25/mo
Unmetered bandwidth = no overage charges, 7 day free trial
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