Splunk® Enterprise

Getting Data In

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About indexed field extraction

When Splunk Enterprise indexes data, it parses the data stream into a series of events. As part of this process, it adds a number of fields to the event data. These fields include default fields that it adds automatically and any custom fields that you specify.

The process of adding fields to events is known as field extraction. There are two types of field extraction:

  • Indexed field extraction, which was described briefly at the start of this topic and which forms the basis for this chapter. Splunk Enterprise stores these fields in the index, and the fields become part of the event data.
  • Search-time field extraction, which takes place when you search through data. Splunk Enterprise creates those fields on the fly and does not store them in the index. See "About fields" in the Knowledge Manager Manual for information about this type of field extraction.

There are two types of indexed fields:

Note: When working with fields, consider that most machine data either does not have structure or has structure that changes constantly. For this type of data, Splunk Enterprise recommends using search-time field extraction for the purposes of flexibility. Search-time field extraction is trivial to modify within Splunk Enterprise once you set it.

Other types of data might exhibit a more fixed structure, or the structure might already be defined within the data or events in the file. Splunk Enterprise provides the option to read the structure of these kinds of files (such as comma-separated value files (CSV), tab-separated value files (TSV), pipe-separated value files, and JavaScript Object Notation (JSON) data sources) and perform field mapping at index time. To read about how this works, read "Extract data from files with headers" in this manual.

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About default fields (host, source, sourcetype, and more)

This documentation applies to the following versions of Splunk® Enterprise: 6.2.0, 6.2.1, 6.2.2, 6.2.3, 6.2.4, 6.2.5, 6.2.6, 6.2.7, 6.2.8, 6.2.9, 6.2.10, 6.2.11, 6.2.12, 6.2.13, 6.2.14, 6.2.15


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