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From Narendra Sharma <narendra.sha...@gmail.com>
Subject Re: Cassandra 0.7 - Impact of row size and columns on compaction
Date Mon, 06 Dec 2010 05:27:43 GMT
This is very useful. Thanks Aaron!

-Naren

On Sun, Dec 5, 2010 at 12:35 PM, Aaron Morton <aaron@thelastpickle.com>wrote:

> AFAIK if the entire row can be read into memory the compaction will be
> faster. The in_memory_compaction_limit_in_mb setting is used to decide how
> big the row can be before it has to use a slower two pass process.
>
> Also my understanding is that one of the main factors for compaction is the
> number of over-writes for rows / columns. e.g if the data for a row is
> spread over a lot of ss tables (for new columns and/or updates and/or
> deletes) it will take longer to compact that row.
>
> Hope that helps.
> Aaron
>
>
> On 04 Dec, 2010,at 09:23 AM, Narendra Sharma <narendra.sharma@gmail.com>
> wrote:
>
> What is the impact (performance and I/O) of row size (in bytes) on
> compaction?
> What is the impact (performance and I/O) of number of super columns and
> columns on compaction?
>
> Does anyone has any details and data to share?
>
> Thanks,
> Naren
>
>

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