Re: fq in SolrCloud

[Keith L]

Caches are stored on the Java heap for each instance of a searcher. The
filter cache would be different per replica, same for the doc cache, and
query cache

On Fri, Feb 5, 2016 at 8:47 AM Tom Evans  wrote:

> I have a small question about fq in cloud mode that I couldn't find an
> explanation for in confluence. If I specify a query with an fq, where
> is that cached, is it just on the nodes/replicas that process that
> specific query, or will it exist on all replicas?
>
> We have a sub type of queries that specify an expensive join condition
> that we specify in the fq, so that subsequent requests with the same
> fq won't have to do the same expensive query, and was wondering
> whether we needed to ensure that the query goes to the same node when
> we move to cloud.
>
> Cheers
>
> Tom
>

Re: fq in SolrCloud

[Shawn Heisey]

On 2/5/2016 8:56 AM, Keith L wrote:
> Caches are stored on the Java heap for each instance of a searcher. The
> filter cache would be different per replica, same for the doc cache, and
> query cache
>
> On Fri, Feb 5, 2016 at 8:47 AM Tom Evans  wrote:
>
>> I have a small question about fq in cloud mode that I couldn't find an
>> explanation for in confluence. If I specify a query with an fq, where
>> is that cached, is it just on the nodes/replicas that process that
>> specific query, or will it exist on all replicas?

Keith already answered this.  Cache entries will only exist on the node
where the query was handled.

>> We have a sub type of queries that specify an expensive join condition
>> that we specify in the fq, so that subsequent requests with the same
>> fq won't have to do the same expensive query, and was wondering
>> whether we needed to ensure that the query goes to the same node when
>> we move to cloud.

SolrCloud will normally load balance queries across the entire cluster,
even if you send every query to the same node.  This is inherent in the
design of SolrCloud.  That behavior can be overridden with the
"preferLocalShards" option.  This option *might* help performance in a
very lightly used cluster, but is NOT recommended for a busy cluster.

See the end of this page (before the comments):

https://cwiki.apache.org/confluence/display/solr/Distributed+Requests

Here's the issue where the option was added to version 5.1:

https://issues.apache.org/jira/browse/SOLR-6832

Thanks,
Shawn

fq in SolrCloud

[Tom Evans]

I have a small question about fq in cloud mode that I couldn't find an
explanation for in confluence. If I specify a query with an fq, where
is that cached, is it just on the nodes/replicas that process that
specific query, or will it exist on all replicas?

We have a sub type of queries that specify an expensive join condition
that we specify in the fq, so that subsequent requests with the same
fq won't have to do the same expensive query, and was wondering
whether we needed to ensure that the query goes to the same node when
we move to cloud.

Cheers

Tom