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From Anuj Wadehra <anujw_2...@yahoo.co.in>
Subject Scenarios which need Repair
Date Mon, 08 Feb 2016 18:14:10 GMT
Hi,

Setup:
--------
We are on 2.0.14. We have some deployments with just one DC(RF:3) while others with two DCs
(RF:3,RF:3).
We ALWAYS use LOCAL_QUORUM for both Reads and Writes. 

Scenario:
---------
We used to run nodetool repair on all tables every gc_grace_seconds. Recently, we decided
to identify tables which really need repair and only run repair on those tables.

We have identified basically two kinds of tables which don't need repair:
TYPE-1 Tables which have only inserts, no upserts and delete by TTL.
TYPE-2 Tables with a counter column. I don't have much experience with counters but I can
explain the use case.
We use a counter column to keep check on our traffic rate.Values are usually updated numerous
times in a minute and we need not be ACCURATE with the value-few values here and there are
OK.

Questions:
--------------
Can we COMPLETELY avoid maintenance repair on TYPE-1 and TYPE-2 tables? If yes, will there
be any side effect of not repairing such data often in case of dropped mutations, failure
scenarios etc.?
What will be the scenarios when repair would be needed on such tables?
   
  
Thanks
Anuj   
   
    

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