IBM Operations Analytics - Log Analysis, Version 1.3.2

Percentile statistical functions

You can use the statistical function to return values for specified percentiles.

You can use the Search REST API or the user interface to create percentile statistical functions.

For example, to query the maximum and minimum results for the 50th, 95th, and 99th percentiles with the Search REST API, you enter "stats": ["min", "max", "percentile,50,95,99"]. The facet response is:

  {
     "min": 10,
     "max", 1000,
     "percentile":
     {
         "50": 100,
         "95": 200,
         "99": 225
     }
}

Percentile queries are not calculated incrementally, unlike the other queries that are used in Log Analysis. This fact means that the query needs to run over the entire time range before it can return any results.Log Analysis limits the number of asynchronous windows that can run simultaneously for this function. This property is set in the MAX_NON_INCREMENTAL_WINDOWS property in theunitysetup.properties. The default value is 2.

For example, if you specify a percentile query based on a time range from August 1 2015 to August 10 2015 and MAX_NON_INCREMENTAL_WINDOWS=5 and COLLECTION_ASYNC_WINDOW=1d, only the most recent 5 days of data that is returned by the query are considered for percentile evaluation.

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