Limiting Results of a Splunk Subsearch
A Splunk subsearch is a sub-section of a main search. The sub-section enables you to narrow your results by time and date. For example, you can limit the results to matches within 30 days of the main search. Or, you can limit it to matches that are earlier or later than the main search results.
Limiting subsearch results to matches that are earlier or later than the main search results
To limit the results of a subsearch to matches that are earlier or later than the results of the main search, use the usetime option. The usetime argument specifies the number of minutes that a particular result must have existed. It can be used either explicitly or implicitly. If used in a subsearch, usetime=true will eliminate results that are earlier or later than the main search results. By default, subsearches return a maximum of 10,000 results, but every command has the ability to change that maximum.
The append command merges the results of a secondary search with the results of the main search. The results of a secondary search are usually added to the bottom of the main search results. The append command only works on historical data, not real-time. However, it can be used to group events using the stats command.
Limiting the results of a subsearch to matches that are earlier or later than the results of the main search is useful for obtaining more information on a particular timeframe. For example, you might want to search for the most active host within the last hour. You can then use the result of the subsearch as the criteria for the main search. In addition, you can use the join command to incorporate the processing of the subsearch into the main search. This helps to reduce the processing time of the main search and preview results.
Limiting subsearch results to matches that are later than the main search results allows you to narrow down your results by looking at a particular field. For example, if you’re interested in products that were purchased in the past month, you can limit subsearch results to matches that are later than those from the main search.
In addition to using the lookup command to group events, you can also use the stats command to perform statistical functions on the events. You can also view the raw event data using the transaction command. By using this command, you can also filter the events by date or field.
To limit the results of a subsearch, you can specify the maximum number of matches for the subsearch. This option is usually used in simple subsearches and requires a smaller dataset. This command is ideal for small subsearches.
However, there are some drawbacks to using a subquery. It can be a performance hog, depending on the number of distinct IP addresses it has to process. Because the top command must keep track of all distinct IP addresses and return only the top result, it can cause a subquery to run slowly.
Limiting subsearch results to matches that are distinct IP addresses match
In some scenarios, limiting the results of a subsearch to matches that are distinct IP addresses can help you get the results you need quickly. However, it can be a performance drain, especially when you’re working with a large number of IP addresses. Depending on how big the IP address database is, a subsearch can return up to 10,000 matches and take up to 60 seconds to run. To avoid this, limit the number of matches you process with each subsearch.
Limiting subsearch results to matches that are in the past 30 days
For small subsearches, it is best to use the join command to group the results based on product_id. Otherwise, Splunk software imposes default limits. Limiting results to matches from the past 30 days is useful when you want to find a specific subset of data.
Limiting results to the last 30 days can be done in two ways. One is by using the usetime parameter and the other is by using the earlier value. The earlier value excludes results that are more than 30 days old. The latter value also omits matches that occurred in the same day as the current date.