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From Amit Shah <amits...@gmail.com>
Subject Re: Disabling HBase Block Cache
Date Fri, 25 Mar 2016 13:39:47 GMT
I noticed that the charts <http://i.imgur.com/ZEJTHWt.png>on cloudera
indicate no block usage when the group by query is executed. This probably
means that the block cache is disabled. The only strange fact is that the
hbase shell describe command gave BLOCKCACHE => 'true'. It would be great
if someone could throw some light on this.

P.S - Though disabling the block cache didn't speed up the group by query
but that seems like a separate topic of discussion.

Thanks!

On Fri, Mar 25, 2016 at 1:34 PM, Amit Shah <amits.84@gmail.com> wrote:

> Hi,
>
> I am using apache hbase (version 1.0.0) and phoenix (version 4.6) deployed
> through cloudera. Since my aggregations with group by query is slow, I want
> to try out disabling the block cache for a particular hbase table. I tried
> a couple of approaches but couldn't succeed. I am verifying if the block
> cache is enabled/disabled through the hbase shell - describe 'my_table'
> command.
>
> 1. Set 'hfile.block.cache.size' property from cloudera console to 0
>
> 2. alter 'myTable', CONFIGURATION => {NAME => 'myColumnFamily', BLOCKCACHE
> => 'false'}
>
> Even after the above two steps, I get BLOCKCACHE => 'true' in the describe
> command output
>
> COLUMN FAMILIES DESCRIPTION {NAME => '0', DATA_BLOCK_ENCODING =>
> 'FAST_DIFF', BLOOMFILTER => 'ROW', REPLICATION_SCOPE => '0', COMPRESSION =>
> 'NONE', VERSIONS => '1', MIN_VERSIONS => '0', TTL => 'FOREVER',
> KEEP_DELETED_CELLS => 'FALSE', BLOCKSIZE => '65536', IN_MEMORY => 'false',
> BLOCKCACHE => 'true'}
>
> What could be going wrong? Any suggestions?
>
> Thank you.
>
>
>

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