The LogReduce button in the Messages tab allows you to apply the logreduce operator automatically to the results of a non-aggregated search.
The LogReduce algorithm uses fuzzy logic to cluster messages together based on string and pattern similarity. You can use the logreduce operator to quickly assess activity patterns for things like a range of devices or traffic on a website. Focus the LogReduce algorithm on an area of interest by defining that area in the keyword expression.
For information on how to interpret and influence the outcome of LogReduce results, see Detecting Patterns with LogReduce and Influencing the LogReduce Outcome.