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From Artur Siekielski <>
Subject Re: Performance penalty of multiple UPDATEs of non-pk columns
Date Fri, 22 May 2015 13:30:42 GMT
Thanks, I wasn't sure if memtables and sstables contain only the newest 
values (I though replication might require storing old values).

So the number of lookups for a newest value should be bound by 
max_compaction_threshold setting. Looks to me it's safe to perform many 
UPDATEs of non-pk columns.

On 05/21/2015 11:48 AM, Jens Rantil wrote:
> Artur,
> That's not entirely true. Writes to Cassandra are first written to a
> memtable (in-memory table) which is periodically flushed to disk. If
> multiple writes are coming in before the flush, then only a single
> record will be written to the disk/sstable. If your have writes that
> aren't coming within the same flush, they will get removed when you are
> compacting just like you say.
> Unfortunately I can't answer this regarding Counters as I haven't worked
> with them.
> Hope this helped at least.
> Cheers,
> Jens

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