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From Stack <st...@duboce.net>
Subject Re: Blockcache Eviction on Write?
Date Mon, 31 Mar 2014 21:59:16 GMT
On Mon, Mar 31, 2014 at 10:37 AM, Rendon, Carlos (KBB) <CRendon@kbb.com>wrote:

> Table does not exist yet. I'm expecting random access across the rowkey
> namespace. I also expect bursts of access to a given row, all of which will
> change its contents and also read it.
>
> My question is from reading here:
> https://hbase.apache.org/book/regionserver.arch.html#block.cache
> that blockcache wastes memory/CPU/GCs if there aren't many hits to it or
> if you have random writes that you typically don't read. So I was wondering
> if writing on every read had the same effect.
>
> After reading the recent thread "Cache invalidation in Blockcache" I can
> see that during bursts the reads would be coming from the memstore and also
> that reads still need to be made to the underlying HFiles because data from
> both sources are merged together to produce a result.
>
> In the scenario I have, it sounds like it is useful to have the HFile
> blocks cached in the blockcache, even if the data ultimately is returned
> from the memstore due to a recent write.
>


And enable cache on write if you are frequently going to be just reading
back what you wrote?

St.Ack

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