anchor.diff:  = SolrCloud Autoscaling Triggers
  +:page-tocclass: right
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positive.code: Additionally, monitoring can be restricted to a list of collections; by default
  all collections are monitored.
  
  This trigger supports the following configuration parameters (all thresholds are exclusive):
  
  `aboveBytes`:: upper threshold in bytes. This value is compared to the `INDEX.sizeInBytes` metric.
  
  `belowBytes`:: lower threshold in bytes. Note that this value should be at least 2x smaller than
  `aboveBytes`
  
  `aboveDocs`:: upper threshold expressed as the number of documents. This value is compared with `SEARCHER.searcher.numDocs` metric.
  +
  NOTE: Due to the way Lucene indexes work, a shard may exceed the `aboveBytes` threshold
  even if the number of documents is relatively small, because replaced and deleted documents keep
  occupying disk space until they are actually removed during Lucene index merging.
  
  `belowDocs`:: lower threshold expressed as the number of documents.
  
  `aboveOp`:: operation to request when an upper threshold is exceeded. If not specified the
  default value is `SPLITSHARD`.
  
  `belowOp`:: operation to request when a lower threshold is exceeded. If not specified
  the default value is `MERGESHARDS` (but see the note above).
  
  `collections`:: comma-separated list of collection names that this trigger should monitor. If not
  specified or empty all collections are monitored.
  
  Events generated by this trigger contain additional details about the shards
  that exceeded thresholds and the types of violations (upper / lower bounds, bytes / docs metrics).
  
  .Example:
  This configuration specifies an index size trigger that monitors collections "test1" and "test2",
  with both bytes (1GB) and number of docs (1 million) upper limits, and a custom `belowOp`
  operation `NONE` (which still can be monitored and acted upon by an appropriate trigger listener):
  
negative.code: for over 20 minutes. If the rate falls below 0.01 and persists for 20 min the trigger will
  request not only replica deletions (leaving at most 1 replica per shard) but also it may
  request node deletion.
  
  [source,json]
  ----
  {
  