Clarifying withoutFetch() with LevelDB and

Luke Bakken lbakken at basho.com
Wed May 13 09:46:54 EDT 2015


Hi Daniel,

What version of the Java client are you using?

Any reason you're on such an old version of Riak?

What is the size of each object written?
--
Luke Bakken
Engineer
lbakken at basho.com


On Wed, May 13, 2015 at 4:48 AM, Daniel Iwan <iwan.daniel at gmail.com> wrote:
> Hi
>
> I'm using 4 node Riak cluster v1.3.1
>
> I wanted to know a little bit more about using withoutFetch() option when
> used with levelDB.
> I'm trying to write to a single key as fast as I can with n=3.
> I deliberately create siblings by writing with stale vclock. I'm limiting
> number of writes to 1000 per key to keep size of Riak object under control
> and then I switch to another key. Siblings will probably never be resolved
> (or resolved in realtime during sporadic reads)
>
> Single write operation is about 250 bytes, rate 10-80 events per sec which
> gives 3-20kB per second per node. So roughly 100kB / s for the cluster.
>
> During the test I see activity on the on disk via iostat and it's between
> 20-30 MB/s on each node.
> Even taking into account multiple copies and overhead of Riak (vclocks etc)
> this seems to be pretty high rate.
> I don't see any read activity which suggest withoutFetch() works as
> expected.
> After 2 mins of tests leveldb on each node is 250MB is size, before test
> (11MB)
>
> Am I using it incorrectly?
> Is writing in this way to a single key a good idea or will I be bitten by
> something?
> How to explain high number of MB written to disks?
>
> Regards
> Daniel
>
>
>
>
>
>
>
>
> --
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>
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