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From Tomas Fernandez Lobbe <>
Subject Re: Limit search queries only to pull replicas
Date Mon, 08 Jan 2018 19:42:56 GMT
This feature is not currently supported. I was thinking in implementing it by extending the
work done in SOLR-10880. I still didn’t have time to work on it though.  There is a patch
for SOLR-10880 that doesn’t implement support for replica types, but could be used as base.


> On Jan 8, 2018, at 12:04 AM, Ere Maijala <> wrote:
> Server load alone doesn't always indicate the server's ability to serve queries. Memory
and cache state are important too, and they're not as easy to monitor. Additionally, server
load at any single point in time or a short term average is not indicative of the server's
ability to handle search requests if indexing happens in short but intense bursts.
> It can also complicate things if there are more than one Solr instance running on a single
> I'm definitely not against intelligent routing. In many cases it makes perfect sense,
and I'd still like to use it, just limited to the pull replicas.
> --Ere
> Erick Erickson kirjoitti 5.1.2018 klo 19.03:
>> Actually, I think a much better option is to route queries to server load.
>> The theory of preferring pull replicas to leaders would be that the leader
>> will be doing the indexing work and the pull replicas would be doing less
>> work therefore serving queries faster. But that's a fragile assumption.
>> Let's say indexing stops totally. Now your leader is sitting there idle
>> when it could be serving queries.
>> The autoscaling work will allow for more intelligent routing, you can
>> monitor the CPU load on your servers and if the leader has some spare
>> cycles use them .vs. crudely routing all queries to pull replicas (or tlog
>> replicas for that matter). NOTE: I don't know whether this is being
>> actively worked on or not, but seems a logical extension of the increased
>> monitoring capabilities being put in place for autoscaling, but I'd rather
>> see effort put in there than support routing based solely on a node's type.
>> Best,
>> Erick
>> On Fri, Jan 5, 2018 at 7:51 AM, Emir Arnautović <
>>> wrote:
>>> It is interesting that ES had similar feature to prefer primary/replica
>>> but it deprecating that and will remove it - could not find explanation why.
>>> Emir
>>> --
>>> Monitoring - Log Management - Alerting - Anomaly Detection
>>> Solr & Elasticsearch Consulting Support Training -
>>>> On 5 Jan 2018, at 15:22, Ere Maijala <> wrote:
>>>> Hi,
>>>> It would be really nice to have a server-side option, though. Not
>>> everyone uses Solrj, and a typical fairly dummy client just queries the
>>> server without any understanding about shards etc. Solr could be clever
>>> enough to not forward the query to NRT shards when configured to prefer
>>> PULL shards and they're available. Maybe it could be something similar to
>>> the preferLocalShards parameter, like "preferShardTypes=TLOG,PULL".
>>>> --Ere
>>>> Emir Arnautović kirjoitti 14.12.2017 klo 11.41:
>>>>> Hi Stanislav,
>>>>> I don’t think that there is a built in feature to do this, but that
>>> sounds like nice feature of Solrj - maybe you should check if available.
>>> You can implement it outside of Solrj - check cluster state to see which
>>> shards are available and send queries only to pull replicas.
>>>>> HTH,
>>>>> Emir
>>>>> --
>>>>> Monitoring - Log Management - Alerting - Anomaly Detection
>>>>> Solr & Elasticsearch Consulting Support Training -
>>>>>> On 14 Dec 2017, at 09:58, Stanislav Sandalnikov <
>>>> wrote:
>>>>>> Hi,
>>>>>> We have a Solr 7.1 setup with SolrCloud where we have multiple shards
>>> on one server (for indexing) each shard has a pull replica on other servers.
>>>>>> What are the possible ways to limit search request only to pull type
>>> replicase?
>>>>>> At the moment the only solution I found is to append shards parameter
>>> to each query, but if new shards added later it requires to change
>>> solrconfig. Is it the only way to do this?
>>>>>> Thank you
>>>>>> Regards
>>>>>> Stanislav
>>>> --
>>>> Ere Maijala
>>>> Kansalliskirjasto / The National Library of Finland
> -- 
> Ere Maijala
> Kansalliskirjasto / The National Library of Finland

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