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Accumulo, mail # user - 0% Data Cache Hit Rate


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Re: 0% Data Cache Hit Rate
Keith Turner 2013-03-11, 19:02
You may need to set the following property to true for the table.
This enables caching data for a table.  It defaults to false.

table.cache.block.enable

Also take a look at the following props.  These determine how much
memory a tserver uses for caching.

tserver.cache.data.size
tserver.cache.index.size

The following props enables caching rfile indexes for a table, it
defaults to true.

table.cache.index.enable

Keith
On Mon, Mar 11, 2013 at 2:48 PM, Slater, David M.
<[EMAIL PROTECTED]> wrote:
> Hi,
>
>
>
> I have a four-node setup, and I’m running some intensive query operations
> that need to go through all of the rows (though only one or two column
> families). While I don’t expect this to be fast by any means, I wanted to
> make sure that I had a decent baseline before comparing this to more indexed
> versions of querying. Here is the problem: Two of my nodes have very low
> data cache hit rates, wand I assume that this would greatly impact the query
> efficiency. Is this correct?
>
>
>
> All four of my nodes have a 99% index cache hit rate, but the data cache hit
> rates are:
>
> Node 1: 96%
>
> Node 2: 95%
>
> Node 3: 67%
>
> Node 4: 0%
>
> (All four are data nodes; the name node is #1)
>
>
>
> I’m not seeing any warnings or errors in the logs, and I couldn’t find much
> online about it, so I thought I would check here. Does anyone have a
> suggestion as for how to fix it? Could this be related to the system
> swappiness at all? (I currently have swappiness set to 0.)
>
>
>
> Thanks for the help,
> David Slater