Joins two LogScale searches. When joining two searches, you need to define the keys/fields that are used to match up results. This is done using the field=name or field=[name,name,...] parameter. If you want to join on a single field name, you can use the syntax

logscale
fieldName =~ join(...)

to specify the field.

If the subquery has a different field that you want to match against, then use the parameter key=[name1,name2,...] to designate the names of keys inside the subquery. The value of keys defaults to the value of field.

join() is a filter function which in the default mode=inner lets the events through that match on the join keys. If you specify mode=left then events that do not match the join key(s) will also be let through.

If you specify include=[field, field, ...] then those fields are extracted from the result of the subquery, and added to matching events. For events in the subquery that do not have one or more of the named include fields, the output will be the empty string.

Using the parameter max=N (which defaults to max=1) you can specify how many rows/events are picked up in the subquery. If a subquery has multiple events with the same join key, then up to max rows are emitted.

You can use the parameters start and end to specify an alternative time interval for the query. The parameter view can be used to direct the subquery to run in a different repository or view, and the live=true|false parameter can be used to control if the subquery runs as a live query. The defaults for all these parameters are inherited from the main query containing the join(...) usage.

The join() function also has a concept of a maximum size of the resultset of the inner query specified with the limit=100000 parameter.

Warning

The join() function does two passes over the data and can therefore not run truly live.

When used in a live query, the query will be run in a repeated mode instead, in which the server chooses the repetition interval based on the resources used by the function.

This can impact the liveness of the query, in that long-running repeated queries can be throttled, and thus be less live than expected.

Function Traits: Negatable, Transformation

ParameterTypeRequiredDefaultDescription
endstringoptionalEnd of main query End of time interval of subquery (milliseconds since UTC or 2d, 24h, 10sec, etc).
fieldArray of stringsrequired  Specifies which field in the event (log line) must match the given column value.
includeArray of stringsoptionalnone Specifies columns to include from the subquery.
keyArray of stringsoptional  Specifies which fields of the subquery to join on. Defaults to the value of the field parameter.
limitnumberoptional100000 Specifies the maximum number of rows in the subquery.
  Minimum1 
  Maximum200000 
livebooleanoptionalSame as main query Control if the subquery runs as live or static query.
maxnumberoptional1 Maximum number of events found in subquery if several share join key.
modestringoptionalinner Specifies the mode (inner or left) of the join.
  Valid Valuesinner
   left
query[a]Functionoptional  The subquery to execute producing the values to join with.
repostringoptionalRepo of main query Specify which view/repo in which to perform the subquery.
startstringoptionalStart of main query Start of time interval of subquery (milliseconds since UTC or 2d, 24h, 10sec, etc).
viewstringoptionalView of main query Specify which view/repo in which to perform the subquery.

[a] The argument name query can be omitted.

The parameter name for query can be omitted; the following forms are equivalent:

logscale
join("value")

and:

logscale
join(query="value")

Find some examples at Query Joins section.