When is anti-entropy repair required?

[eugene miretsky <eu...@gmail.com>]

Hi,

Trying to get some clarifications on this post: https://docs.datastax.
com/en/cassandra/3.0/cassandra/operations/opsRepairNodesWhen.html

As far as I understand it, repairs to account for the fact that nodes could
go down (for short of long period of time)

The 2 main reasons for repairing are:

   1. To make sure date is consistent
   2. To make sure tombstones don't creep back

If I have a time series data model, with TWCS compaction where I never
update rows and hence don't care about either of the above (the whole
SSTable just expires after a few days ), do I even need to run repairs?

Re: When is anti-entropy repair required?

[Alain RODRIGUEZ <ar...@gmail.com>]

Hi Eugene,


> If I have a time series data model, with TWCS compaction where I never
> update rows and hence don't care about either of the above (the whole
> SSTable just expires after a few days ), do I even need to run repairs?


Probably not. I think you can go without repairs. Using only time series
with TTL is fine as long as you don't delete anything. And TWCS is a very
good fit as it will allow Cassandra to remove some expired SSTable without
compacting the data.

If consistency matters, use CL = LOCAL_QUORUM on Reads & Writes though.

C*heers,
-----------------------
Alain Rodriguez - @arodream - alain@thelastpickle.com
France

The Last Pickle - Apache Cassandra Consulting
http://www.thelastpickle.com

2017-03-28 0:12 GMT+02:00 eugene miretsky <eu...@gmail.com>:

> Hi,
>
> Trying to get some clarifications on this post: https://docs.datastax.co
> m/en/cassandra/3.0/cassandra/operations/opsRepairNodesWhen.html
>
> As far as I understand it, repairs to account for the fact that nodes
> could go down (for short of long period of time)
>
> The 2 main reasons for repairing are:
>
>    1. To make sure date is consistent
>    2. To make sure tombstones don't creep back
>
> If I have a time series data model, with TWCS compaction where I never
> update rows and hence don't care about either of the above (the whole
> SSTable just expires after a few days ), do I even need to run repairs?
>