News for hackers. Stuff that matters.

A comment on NewSQL databases fail to guarantee consistency and I blame Spanner. Parent comment

Re:NewSQL databases fail to guarantee consistency and I blam... by oconnor663 on Friday September 21, 2018 @03:22PM (#18042005)
Does running on 3-5 machines give you the advantage of being able to apply kernel patches and restart machines without bringing down the whole system? That might matter to people with paying customers, even if in theory they could've replaced their 3 machines with one bigger one.
[ Parent | on HN ]
Re:NewSQL databases fail to guarantee consistency and I blam... by Quekid5 on Friday September 21, 2018 @04:38PM (#18042494)
It may, but if your customer can't tolerate/afford 5-10 minutes of downtime you're already into "big league" territory. I could see a case if you're rolling out gradually, but with only 3-5 machines you're not really going to notice any subtle problems in a 1-vs-2 or 2-vs-3 situation.
[ Parent | on HN ]
Re:NewSQL databases fail to guarantee consistency and I blam... by mmt on Friday September 21, 2018 @08:35PM (#18043774)
I'm not sure anyone would ever actually have only one machine, without a failover option, and failing over had better not bring down the whole system.
[ Parent | on HN ]
Re:NewSQL databases fail to guarantee consistency and I blam... by yjftsjthsd-h on Friday September 21, 2018 @10:32PM (#18044137)
But now we're back to a distributed system
[ Parent | on HN ]
Re:NewSQL databases fail to guarantee consistency and I blam... by mmt on Saturday September 22, 2018 @01:16AM (#18044583)
I don't think that's true, in the usual sense of the term.

When a replica is used as a read slave, that introduces problems with (strong) consistency, that definitely starts to resemble any other distributed system.

Adding automated failover adds the need for some kind of consensus algorithm, another feature of distributed systems.

However, if failover is manual, for example, then 2 nodes can be nearly indistinguishable from 1 node, if no failover occurs.

It also strains the definition of "distributed" if both nodes are adjacent, possibly even with direct network and/or storage connections to each other.

[ Parent | on HN ]