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:
- Default fields, which Splunk automatically adds to each event. See "About default fields" in this chapter.
- Custom fields, which you specify. See "Create custom fields at index time" in this manual.
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.
Tune timestamp recognition for better indexing performance
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