Events

The data stored in Humio are called events. An event is a piece of data and an associated timestamp.

Examples of events include:

  • Log Lines
  • Metric Data
  • Analytics Data

but ANY piece of data with an associated timestamp can be thought of as an event.

Example
When data is sent to Humio - in this example a log line - the associated parser converts the data into an event. If Humio received:

[2018-10-11 22:00:10] INFO - User Logged In. userId=97110

This might be turned into an event data containing the following fields:

Field Value
@rawstring [2018-10-11 22:00:10] INFO - User Logged In. userId=97110
@id 3gqidgqi_uwgdwqu121duqgdw2iqwud_721gqwdugqdwu1
@timestamp 2018-10-11 22:00:10
@timezone Z
#repo server-logs
#type my-parser
loglevel INFO
message User Logged In.
userId 97110

Field Types

There are three types of fields:

Metadata Fields

Each event has some metadata attached to it on ingestion, e.g. all events will have an @id, @timestamp, @timezone, @display and @rawstring field.

Notice that metadata fields start with all @ to make them easy to identity.

The three most important are @timestamp, @rawstring, and @display and will be described in detail below.

Tag Fields

Tags fields define how events are physically stored and indexed. They are also used for speeding up queries.

Users can associate custom tags as part of the parsing and ingestion process but their use is usually very limited. The only built-in tags are #repo and #type and both are described in detail below.

Usually the client sending data to Humio will be configured to include #host and #source tags that contain the hostname and file that the event was read from.

User Fields

Any field that is not a tag or metadata is a user field. They are extracted at ingest by a parser or at query time by a regular expression. User fields are usually the interesting part of an event, containing application specific information.

Field: @rawstring

Humio represents the original text of the event in the @rawstring attribute.

One of the greatest strengths of Humio is that it keeps the original data and nothing is thrown away at ingest. This allows you to do free-text searching across all logs and to extract virtual fields at query time for parts of the data you did not even know would be important.

You can read more about free-text search and extracting fields in the search documentation.

Field: @timestamp

The timestamp of an event is represented in the @timestamp field. This field defines where the event is stored in Humio’s database and is what defines wether an event is included in search results when searching a time range.

The timestamp needs special treatment when parsing incoming data during ingestion.

Field: @display

By default Humio will display the content of the @rawstring field in the Event List. Sometimes this is not what you want, e.g the message could be very long and the relevant information be at the end of @rawstring, or you might want to be able to see a single field contained in the message.

You can fix this by assigning a value to the @display field. For example you might only want to see the method and url fields from your event data. To achieve this you can use Humio’s format function combined with the @display field to achieve this.

The following query extracts the method and url fields from the event data and sets the @display field using the format function:

@display := format("%s %s", field=[method, url])

and outputs the results as demonstrated in the example below:

GET /path/to/page
POST /path/to/other/page

As you can see Humio uses a printf-like syntx to format the resulting message.

Field: #repo

All events have a special #repo tag that denotes the repository that the event is stored in. This is useful in cross-repository searches when using views.

Field #type

The type field is the name of the parser used to ingest the data.