RE: Blockcache Eviction on Write?

["Rendon, Carlos (KBB)" <CR...@kbb.com>]

As far as I can tell the cache on write settings are more global than just the table in question.
https://hbase.apache.org/book/config.files.html

Is there a table-level option or API level option I’m not aware of?
-Carlos


From: saint.ack@gmail.com [mailto:saint.ack@gmail.com] On Behalf Of Stack
Sent: Monday, March 31, 2014 2:59 PM
To: Rendon, Carlos (KBB)
Cc: Hbase-User
Subject: Re: Blockcache Eviction on Write?

On Mon, Mar 31, 2014 at 10:37 AM, Rendon, Carlos (KBB) <CR...@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

Re: Blockcache Eviction on Write?

[Stack <st...@duboce.net>]

On Mon, Mar 31, 2014 at 4:06 PM, Rendon, Carlos (KBB) <CR...@kbb.com>wrote:

>  As far as I can tell the cache on write settings are more global than
> just the table in question.
>
> https://hbase.apache.org/book/config.files.html
>
>
>

That is correct.  BlockCache is by the server currently.  There are no
per-table nor per-cf configs though fellas have been asking for them...

St.Ack


>  Is there a table-level option or API level option I’m not aware of?
>