Evaluate and manipulate fields with multiple values
About multivalue fields
Multivalue fields are parsed at search time, which enables you to process the values in the search pipeline. Search commands that work with multivalue fields include makemv, mvcombine, mvexpand, and nomv. The eval and where commands support functions, such as
mvcount(), mvfilter(), mvindex(), and mvjoin() that you can use with multivalue fields. See Evaluation functions in the Search Reference and the examples in this topic.
If you are using Splunk Enterprise, you can configure multivalue fields in the
fields.conf file to specify how Splunk software detects more than one field value in a single extracted field value. Edit the
$SPLUNK_HOME/etc/system/local/, or your own custom application directory in
$SPLUNK_HOME/etc/apps/. For more information on how to do this, see Configure extractions of multivalue fields with fields.conf in the Knowledge Manager Manual.
If you are using Splunk Cloud and want to configure multivalue fields, file a Support ticket.
If your search produces results, such as a table, the results get written to the
results.csv.gz file. The contents of the
results.csv.gz file include fields that begin with "__mv_". These fields are for internal use only and are used to encode multivalue fields.
Evaluate multivalue fields
One of the more common examples of multivalue fields is email address fields, which typically appear two or three times in a single sendmail event--one time for the sender, another time for the list of recipients, and possibly a third time for the list of Cc addresses.
Count the number of values in a field
mvcount() function to count the number of values in a single value or multivalue field.
In this example, mvcount() returns the number of email addresses in the To, From, and Cc fields and saves the addresses in the specified "_count" fields.
eventtype="sendmail" | eval To_count=mvcount(split(To,"@"))-1 | eval From_count=mvcount(From) | eval Cc_count= mvcount(split(Cc,"@"))-1
This search takes the values in the
To field and uses the
split function to separate the email address on the @ symbol. The
split function is also used on the
Cc field for the same purpose.
If only a single email address exists in the
From field, as you would expect,
mvcount(From) returns 1. If there is no Cc address, the Cc field might not exist for the event. In that situation
mvcount(cc) returns NULL.
Filter values from a multivalue field
mvfilter() function to filter a multivalue field using an arbitrary Boolean expression. The
mvfilter function works with only one field at a time.
In this example, mvfilter() keeps all of the values for the field
eventtype="sendmail" | eval email=mvfilter(match(email, "\.net$") OR match(email, "\.org$"))
Note: This example also uses the
match() function to compare the pattern defined in quotes to the value of
Return a subset of values from a multivalue field
mvindex() function to reference a specific value or a subset of values in a multivalue field. Since the index numbering starts at 0, if you want to reference the 3rd value of a field, you would specify it as 2.
In this example, mvindex() returns the first email address in the "To" field for every email sent by Sender:
eventtype="sendmail" from=Sender@* | eval to_first=mvindex(to,0)
If you want to see the top 3 email addresses that Sender writes to, use the following search.
eventtype="sendmail" from=Sender@* | eval top_three=mvindex(to,0,2)
In this example,
top_three is, itself, a multivalue field.
Manipulate multivalue fields
Use nomv to convert a multivalue field into a single value
You can use the
nomv command to convert values of the specified multivalue field into one single value. The
nomv command overrides the multivalue field configurations that are set in
In this example for sendmail events, you want to combine the values of the senders field into a single value.
eventtype="sendmail" | nomv senders
Use makemv to separate a multivalue field
You can use the
makemv command to separate multivalue fields into multiple single value fields. In this example for sendmail search results, you want to separate the values of the senders field into multiple field values.
eventtype="sendmail" | makemv delim="," senders
After you separate the field values, you can pipe it through other commands. For example, you can display the top senders.
eventtype="sendmail" | makemv delim="," senders | top senders
Use mvexpand to create multiple events based on a multivalue field
You can use the
mvexpand command to expand the values of a multivalue field into separate events for each value of the multivalue field. In this example, new events are created for each value in the multivalue field, "foo".
... | mvexpand foo
Use mvcombine to create a multivalue field from similar events
Combine the values of "foo" with ":" delimiter.
... | mvcombine delim=":" foo
Configure extractions of multivalue fields with fields.conf in the Knowledge Manager Manual.
Extract fields with search commands
About calculating statistics
This documentation applies to the following versions of Splunk® Enterprise: 7.1.0, 7.1.1, 7.1.2, 7.1.3, 7.1.4, 7.1.5, 7.1.6, 7.1.7, 7.2.0, 7.2.1, 7.2.2, 7.2.3, 7.2.4, 7.2.5, 7.2.6