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From Jay Potharaju <jspothar...@gmail.com>
Subject Re: solrcloud load balancing
Date Sun, 23 Oct 2016 01:48:25 GMT
Thanks Erick for the response
I am currently using a load balancer for my solrcloud, but was particularly
interested to know if solrcloud is doing load balancing internally in the
case of a single shard.
All the documentation that I have seen assumes multi-shard scenarios but
not for a single shard. Can you please point me to some code/documenation
that can help me understand this better.

Thanks
Jay

On Sat, Oct 22, 2016 at 6:00 PM, Erick Erickson <erickerickson@gmail.com>
wrote:

> 1) Single shards have some short circuiting in them. And anyway it's
> best to have some kind of load balancer in front or use SolrJ with
> CloudSolrClient. If you just use an HTTP end-point, you have a single
> point of failure if that node goes down.
>
> 2) yes. What it does _not_ include is the time taken to assemble the
> final document list, i.e. get the "fl" parameters. And also note that
> there's "the laggard problem" here. The time will be something close
> to the _longest_ time it takes any replica to respond. Say you have 4
> shards and the replica for one of them happens to hit a 5 second
> stop-the-world GC collection. Your QTime will be 5 seconds+. I really
> have no idea whether the QTime includes the decision process for
> selecting nodes, but I've also never heard of it being significant.
>
> 3) I guess, although I'm not quite sure I understand the question.
> Slow queries will include (roughly) the max of the sub-request QTimes.
>
> Best,
> Erick
>
> On Sat, Oct 22, 2016 at 5:19 PM, Jay Potharaju <jspotharaju@gmail.com>
> wrote:
> > Hi,
> > I am trying to understand how load balancing works in solrcloud.
> >
> > As per my understanding solrcloud provides load balancing when querying
> > using an http endpoint.  When a query is sent to any of the nodes , solr
> > will intelligently decide which server can fulfill the request and will
> be
> > processed by one of the nodes in the cluster.
> >
> > 1) Does the logic change when there is only 1 shard vs multiple shards?
> >
> > 2) Does the QTime displayed is sum of processing time for the query
> request
> > + latency(if processed by another node) + time to decide which node will
> > process the request(which i am guessing is minimal and can be ignored)
> >
> > 3) In my solr logs i display the "slow" queries, is the qtime displayed
> > takes all of the above and shows the correct time taken.
> >
> > Solr version: 5.5.0
> >
> >
> > --
> > Thanks
> > Jay
>



-- 
Thanks
Jay Potharaju

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