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From Ryan Svihla <rsvi...@datastax.com>
Subject Re: batch_size_warn_threshold_in_kb
Date Thu, 11 Dec 2014 20:56:02 GMT
Nothing magic, just put in there based on experience. You can find the
story behind the original recommendation here

https://issues.apache.org/jira/browse/CASSANDRA-6487

Key reasoning for the desire comes from Patrick McFadden:

"Yes that was in bytes. Just in my own experience, I don't recommend more
than ~100 mutations per batch. Doing some quick math I came up with 5k as
100 x 50 byte mutations.

Totally up for debate."

It's totally changeable, however, it's there in no small part because so
many people confuse the BATCH keyword as a performance optimization, this
helps flag those cases of misuse.

On Thu, Dec 11, 2014 at 2:43 PM, Mohammed Guller <mohammed@glassbeam.com>
wrote:
>
>   Hi –
>
> The cassandra.yaml file has property called *batch_size_warn_threshold_in_kb.
> *
>
> The default size is 5kb and according to the comments in the yaml file, it
> is used to log WARN on any batch size exceeding this value in kilobytes. It
> says caution should be taken on increasing the size of this threshold as it
> can lead to node instability.
>
>
>
> Does anybody know the significance of this magic number 5kb? Why would a
> higher number (say 10kb) lead to node instability?
>
>
>
> Mohammed
>


-- 

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Ryan Svihla

Solution Architect

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