Skip to main content
Sumo Logic

LogReduce Operator

The LogReduce algorithm uses fuzzy logic to group 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.

There are two ways to use the operator.

  • Use the LogReduce button displayed on the results table after running a search.
  • Manually add the operator to your query following its syntax.

LogReduce button

When you've already run a search query with non-aggregate results, you can use the LogReduce button in the Messages tab to automatically apply the LogReduce operator to the current results.

  1. Run a search query with non-aggregate results.
  2. In the Messages tab, the LogReduce button displays. Click it to automatically apply the LogReduce operator to your results.

  3. The Signatures tab is displayed with your results. 



  • ... | logreduce [field=<field>] [by <byField>] [limit=<limit>] [, criteria=<criteria>]
Parameter Description
field The field to group by similarity. If no field is provided the raw message is used.
byField Field to group signatures by. Results are returned aggregated.
limit Limits the number of signatures returned. The total number of signatures involved in a search query can be overwhelming, making final results hard to digest and comprehend. Use this parameter to limit the number of returned signatures.
criteria By default, LogReduce tries to find the most anomalous signatures. The criteria parameter can override the default criteria to either of the following values:
  - mostcommon : Signatures that appear most frequently, having the highest counts.
  - leastcommon : Signatures that appear least frequently, having the lowest counts.

Details option

Using the details option launches a new query adding a unique signature ID that allows you to view the logs grouped under that signature. The signature ID is not available to run this manually, you'll need to use the web interface.

After running a LogReduce operation, from the Signatures tab, you can view logs grouped together in a signature. To see the raw log data from signatures the operator provides the details option. You can view details in two ways:

  • Click the number in the Count column for a signature.
  • Check the checkboxes in the Select column for any number of signatures and click the View Details button on the top right of the table.

logreduce details option.png

Details option syntax:

... | logreduce | details <signatureId>

Optimize option

LogReduce Optimize is a scaled-out version of LogReduce that groups logs by existing signatures. You need to prerun LogReduce on new data sources to create its signatures. In many cases, the optimized version provides up to 10x speedup over classic LogReduce on datasets with hundreds of thousands of logs. The only caveat with the optimized version is that some LogReduce classic features are not supported. The table below compares classic LogReduce with its optimized version based on available features and performance:

Features LogReduce LogReduce Optimize
Throughput   ~10x logreduce
Groups logs by existing signatures Yes Yes
Creates new signatures at runtime Yes No
Displays signature relevance Yes No
Allows interactive feedback (favoriting, disliking, editing, splitting, merging) Yes No
Supports details investigation Yes Yes

Optimize option syntax:

... | logreduce [field=<field>] optimize

For example,

  • _sourceCategory=cloudtrail
    | logreduce optimize
  • _sourceCategory=kubernetes-audit
    | json auto
    | logreduce field=object optimize


  1. _sourcecategory = "Labs/AWS/GuardDuty_V8"
    | json keys "resource", "partition", "region"
    | logreduce
  2. _sourcecategory = "Labs/AWS/GuardDuty_V8"
    | json keys "resource", "partition", "region"
    | logreduce(partition) by region limit=5,criteria=mostcommon
  3. The LogReduce operator can act as an aggregate operator, supporting grouping by _timeslice as well as by other dimensions, such as _sourcehost.

    | logreduce by _sourcehost

    By grouping by timeslice, you can determine how signature counts change over a period of time. 

    | timeslice 1m  
    | logreduce by _timeslice

  4. _sourceCategory=MyApp
    | timeslice 1m
    | logreduce by _timeslice limit=5,criteria=mostcommon
    | transpose row _timeslice column signature
  5. _sourceCategory=MyApp
    | logreduce by _sourceHost limit=5,criteria=mostcommon
    | transpose row _sourcehost column signature