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SOLR-11985: ref guide

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SOLR-12511: ref guide

SOLR-12517: ref guide
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Noble Paul 2018-06-27 12:58:08 +10:00
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solr/solr-ref-guide/src/solrcloud-autoscaling-policy-preferences.adoc
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@ -102,7 +102,12 @@ The name of the shard to which the policy rule should apply. If omitted, the rul
The type of the replica to which the policy rule should apply. If omitted, the rule is applied for all replica types of this collection/shard. The allowed values are `NRT`, `TLOG` and `PULL`
`replica`::
The number of replicas that must exist to satisfy the rule. This must be a positive integer. This is a required attribute.
This is a required attribute. The number of replicas that must exist to satisfy the rule. This must be one of
* a positive integer . e.g : "`3`"
* an integer with a decimal value . e.g: "`1.66`" . This means both 1 and 2 are acceptable values but the system would prefer `2`
* a number range. Such as `"3-5"` . This means `3,4,5` are acceptable values
* a percentage value . e.g: `33%` . This is computed to a decimal value at runtime
`strict`::
An optional boolean value. The default is `true`. If true, the rule must be satisfied. If false, Solr tries to satisfy the rule on a best effort basis but if no node can satisfy the rule then any node may be chosen.
@ -151,8 +156,16 @@ Each attribute in the policy may specify one of the following operators along wi
* `<`: Less than
* `>`: Greater than
* `!`: Not
* Range operator `(-)` : a value such as `"3-5"` means a value between 3 to 5 (inclusive). This is only supported in the following attributes
** `replica`
* None means equal
==== Special functions
This supports values calculated at the time of execution.
* `%` : A certain percentage of the value. This is supported by the following attributes
** `replica`
=== Examples of Policy Rules
==== Limit Replica Placement
@ -179,6 +192,35 @@ Place all replicas on a node with system property `availability_zone=us-east-1a`
[source,json]
{"replica": 0, "sysprop.availability_zone": "!us-east-1a"}
===== Use Percentage
====== example 1
Place roughly a maximum of a 3rd of the replicas of a shard in a node. In the following example, the value of replica is computed in real time.
[source,json]
{"replica": "33%", "shard": "#EACH", "node": "#ANY"}
If the no:of of replicas in a shard is `2` , `33% of 2 = 0.66` . This means a node may have a maximum of `1` and a minimum of `0` replicas of each shard.
It is possible to get the same effect by hard coding the value of replica as follows
[source,json]
{"replica": 0.66, "shard": "#EACH", "node": "#ANY"}
or using the range operator
[source,json]
{"replica": "0-1", "shard": "#EACH", "node": "#ANY"}
====== example 2
Distribute replicas across datacenters east and west at a `1:2` ratio
[source,json]
{"replica": "33%", "shard": "#EACH", "sysprop.zone": "east"}
{"replica": "66%", "shard": "#EACH", "sysprop.zone": "west"}
For the above rule to work, all nodes must the started with a system property called `"zone"`
==== Place Replicas Based on Node Role
Do not place any replica on a node which has the overseer role. Note that the role is added by the `addRole` collection API. It is *not* automatically the node which is currently the overseer.