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From Jeff Jirsa <jji...@gmail.com>
Subject Re: Dynamo autoscaling: does it beat cassandra?
Date Mon, 09 Dec 2019 21:02:00 GMT
Expansion probably much faster in 4.0 with complete sstable streaming
(skips ser/deser), though that may have diminishing returns with vnodes
unless you're using LCS.

Dynamo on demand / autoscaling isn't magic - they're overprovisioning to
give you the burst, then expanding on demand. That overprovisioning comes
with a cost. Unless you're actively and regularly scaling, you're probably
going to pay more for it.

It'd be cool if someone focused on this - I think the faster streaming goes
a long way. The way vnodes work today make it difficult to add more than
one at a time without violating consistency, and thats unlikely to change,
but if each individual node is much faster, that may mask it a bit.



On Mon, Dec 9, 2019 at 12:35 PM Carl Mueller
<carl.mueller@smartthings.com.invalid> wrote:

> Dynamo salespeople have been pushing autoscaling abilities that have been
> one of the key temptations to our management to switch off of cassandra.
>
> Has anyone done any numbers on how well dynamo will autoscale demand
> spikes, and how we could architect cassandra to compete with such abilities?
>
> We probably could overprovision and with the presumably higher cost of
> dynamo beat it, although the sales engineers claim they are closing the
> cost factor too. We could vertically scale to some degree, but node
> expansion seems close.
>
> VNode expansion is still limited to one at a time?
>
> We use VNodes so we can't do netflix's cluster doubling, correct? With
> cass 4.0's alleged segregation of the data by token we could though and
> possibly also "prep" the node by having the necessary sstables already
> present ahead of time?
>
> There's always "caching" too, but there isn't a lot of data on general
> fronting of cassandra with caches, and the row cache continues to be mostly
> useless?
>

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