Solr cloud optimizer

[ca...@libero.it]

Hi  all,
I use SolrCloud with  some collections with 3  shards each. 
Every day I insert and remove documents from collections. I  know that solr starts optimizer in background to optimize indexes. 
Which  is the policy that solr applies in order  to start optimizer automatically ? Number of deleted documents? Number of segments? 
Thanks.

Re: Solr cloud optimizer

[Tomas Fernandez Lobbe <tf...@apple.com>]

By default Solr uses the “TieredMergePolicy”[1], but it can be configured in solrconfig, see [2].  Merges can be triggered for different reasons, but most commonly by segment flushes (commits) or other merges finishing.

Here is a nice visual demo of segment merging (a bit old but still mostly applies AFAIK): [3]

[1] https://lucene.apache.org/core/6_6_0/core/org/apache/lucene/index/TieredMergePolicy.html
[2] https://lucene.apache.org/solr/guide/6_6/indexconfig-in-solrconfig.html
[3] http://blog.mikemccandless.com/2011/02/visualizing-lucenes-segment-merges.html

Tomas

> On Sep 7, 2017, at 10:00 AM, calamita.agostino@libero.it wrote:
> 
> 
> Hi  all,
> I use SolrCloud with  some collections with 3  shards each. 
> Every day I insert and remove documents from collections. I  know that solr starts optimizer in background to optimize indexes. 
> Which  is the policy that solr applies in order  to start optimizer automatically ? Number of deleted documents? Number of segments? 
> Thanks.