Query regarding Solr Caches

[Suresh Pendap <SP...@walmartlabs.com>]

Hi,
This question might have been asked on the solr user mailing list earlier. Solr has four different types of Cache DocumentCache, QueryResultCache, FieldValueCache and FilterQueryCache
I would like to know which of these Caches are off heap cache?  Which Caches have the maximum impact on the query latency and it is recommended to configure that Cache?

I also would like to know if there is any document which provides guidelines on performing Capacity planning for a Solr cluster.

Regards
Suresh

Re: Query regarding Solr Caches

[Shawn Heisey <ap...@elyograg.org>]

On 5/11/2017 4:58 PM, Suresh Pendap wrote:
> This question might have been asked on the solr user mailing list earlier. Solr has four different types of Cache DocumentCache, QueryResultCache, FieldValueCache and FilterQueryCache
> I would like to know which of these Caches are off heap cache?

None of them are off-heap.  For a while, there was a forked project
called Heliosearch that did have a bunch of off-heap memory structures,
but it is my understanding that Heliosearch is effectively dead now.

There are at least three issues for bringing this capability to Solr,
but none of them have been added yet.

https://issues.apache.org/jira/browse/SOLR-6638
https://issues.apache.org/jira/browse/SOLR-7211
https://issues.apache.org/jira/browse/SOLR-7210

> Which Caches have the maximum impact on the query latency and it is recommended to configure that Cache?

This is so dependent on your exact index and your exact queries that
nobody can give you a reliable answer to that question.

The filterCache is pretty good at speeding things up when you have
filter queries that get reused frequently, but depending on how your
setup works, it might not provide the most impact.

> I also would like to know if there is any document which provides guidelines on performing Capacity planning for a Solr cluster.

No.  It's not possible to provide general information.  See this:

https://lucidworks.com/sizing-hardware-in-the-abstract-why-we-dont-have-a-definitive-answer/

Thanks,
Shawn