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https://issues.apache.org/jira/browse/SOLR-12495?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16520943#comment-16520943
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Noble Paul commented on SOLR-12495:
-----------------------------------

bq.I see; could {"core": "#MINIMUM", "node": "#ANY"} be included with this 
issue? Along with per-collection balancing, we'll also need cluster-wide 
balancing.

well we already have a global preference which says 
{code}
{"minimize" : "cores"}
{code}

Is there anything that's not already addressed by that? I understand that it 
won't show any violations if you are already in an imbalanced state. 

The problem with implementing a feature like this that  you can clearly have 
conflicts if you create 2 rules as follows. This can always lead to violations 
which are impossible to satisfy
{code}
{"cores" : "#MINIMUM", "node" : "#ANY"}
{"replica" : "#MINIMUM", "shard" : "#EACH", "node" : "#ANY"}
{code}

> Enhance the Autoscaling policy syntax to evenly distribute replicas
> -------------------------------------------------------------------
>
>                 Key: SOLR-12495
>                 URL: https://issues.apache.org/jira/browse/SOLR-12495
>             Project: Solr
>          Issue Type: New Feature
>      Security Level: Public(Default Security Level. Issues are Public) 
>          Components: AutoScaling
>            Reporter: Noble Paul
>            Priority: Major
>
> Support a new function value for {{replica= "#MINIMUM"}}
> {{#MINIMUM}} means the minimum computed value for the given configuration
> the value of replica will be calculated as  {{<= 
> Math.ceil(number_of_replicas/number_of_valid_nodes) }}
> *example 1:*
> {code:java}
> {"replica" : "#MINIMUM" , "shard" : "#EACH" , "node" : "#ANY"}
> {code}
> *case 1* : nodes=3, replicationFactor=4
>  the value of replica will be calculated as {{Math.ceil(4/3) = 2}}
> current state : nodes=3, replicationFactor=2
> this is equivalent to the hard coded rule
> {code:java}
> {"replica" : "<3" , "shard" : "#EACH" , "node" : "#ANY"}
> {code}
> *case 2* : 
> current state : nodes=3, replicationFactor=2
> this is equivalent to the hard coded rule
> {code:java}
> {"replica" : "<3" , "shard" : "#EACH" , "node" : "#ANY"}
> {code}
> *example:2*
> {code}
> {"replica" : "#MINIMUM"  , "node" : "#ANY"}{code}
> case 1: numShards = 2, replicationFactor=3, nodes = 5
> this is equivalent to the hard coded rule
> {code:java}
> {"replica" : "<3" , "node" : "#ANY"}
> {code}
> *example:3*
> {code}
> {"replica" : "<2"  , "shard" : "#EACH" , "port" : "8983"}{code}
> case 1: {{replicationFactor=3, nodes with port 8983 = 2}}
> this is equivalent to the hard coded rule
> {code}
> {"replica" : "<3"  , "shard" : "#EACH" , "port" : "8983"}{code}



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