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From Gen Liu <ge...@zynga.com>
Subject Re: HBase row level cache for random read
Date Thu, 23 Aug 2012 19:06:00 GMT

On 8/18/12 12:33 PM, "Stack" <stack@duboce.net> wrote:

>On Fri, Aug 17, 2012 at 4:42 PM, Gen Liu <geliu@zynga.com> wrote:
>> I assume block cache store compressed data,
>Generally its not, not unless you use block encoding.
Can you be more specific on this?  Are you talking about
So this is only available in 0.94 then? Thanks.
>> one block can hold 6 rows, but in random read, maybe 1 row is ever
>>accessed, 5/6 of the cache space is wasted.
>> Is there a better way of caching for random read. Lower the block size
>>to 32k or even 16k might be a choice.
>We don't seem to list this as an option in this section,
>http://hbase.apache.org/book.html#perf.reading, but yes, if lots of
>random reads, smaller block cache could make a difference.

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