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Accumulo, mail # user - number of query threads for batch scanner


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Re: number of query threads for batch scanner
ameet kini 2012-09-25, 18:45
Probably worth adding that the table mentioned below has a bunch of tablets
on other tablet servers as well, which is why I'm using BatchScanner. I'm
just not sure how the numQueryThreads relates to the number of a concurrent
scans on a given tablet server.

Thanks

On Tue, Sep 25, 2012 at 2:22 PM, ameet kini <[EMAIL PROTECTED]> wrote:

>
> I have a table with 4 tablets on a given tablet server. Depending on the
> numQueryThreads parameter below, I see a varying number of maximum
> concurrent scans on that table. This maximum number varies from 1 to 3
> (i.e., some values for numQueryThreads result in maximum concurrent scan of
> 1, some values result in 2 concurrent scans, etc.). Can someone shed light
> on what is the relationship between numQueryThreads and number of
> concurrent scans?
>
> public BatchScanner createBatchScanner(String tableName,
>                                        Authorizations authorizations,
>                                        int numQueryThreads)
>
> A follow-on question would be what is general rule of thumb for setting
> numQueryThreads? Should it be set to the  # of hosted tablets expected to
> be consumed by that BatchScanner? Should it be the # of tablet servers
> expected to be hit by that BatchScanner? Something else?
>
> Thanks,
> Ameet
>
>
>