Description
This operation returns all the values of a historical lookup row into a JSON field upon successful key correlation.
How does it work in the search window?
Select Create field in the search window toolbar, then select the Lookups category, and choose the Historical Lookup: retrieve json (hlurjson) operation from the dropdown (more info here). You need to specify three arguments:
Argument | Description | Data type |
|---|---|---|
Lookup name mandatory | Choose the lookup you want to use to enrich your table. | string |
Key mandatory | Choose the table field you want to use to correlate with the lookup key field. | same as lookup key field |
Time | Choose the table timestamp you want to use to correlate with the lookup timestamp. It identifies the row with the highest timestamp in the lookup that is before the timestamp in your table. | timestamp |
Existing lookups required To perform these operations, it is necessary to have existing lookups ready for use (visit this article to get help uploading lookups and this article to get help creating query lookups). | ||
Once you specify the adequate arguments and click the Create field button, the new field is added to your table.
The timestamp in your table will be matched with the closest previous lookup timestamp to correlate key values. When the values of the lookup key field match the values of the Key argument, the new field displays all the values of the corresponding lookup row. If there is no match, it displays null. Your new table field will display ranges of recurring values according to the time slot they belong to, which corresponds to the intervals between the lookup timestamps.
The data type of the values in the new column will be JSON. You can then split the resulting JSON objects into their different key/value pairs and transform them into different data types using the operations in the JSON group.
How does it work in LINQ?
Use the create field operator select... as new_field and add the operation syntax to create the new column. This is the syntax for the Historical lookup:retrieve json (hlurjson) operation:
hlurjson("Lookup_name", Key, Time)
The complete syntax with both the create field operator and the operation syntax is:
select hlurjson("Lookup_name", Key, Time) as new_field
Existing lookups required
To perform these operations, it is necessary to have existing lookups ready for use (visit this article to get help uploading lookups and this article to get help creating query lookups).
Syntax special considerations
"LOOKUP_NAME" → This must be the name of lookup that contains the data you want to use to enrich your data. The name of an inexistent lookup will return an error when running the query.
KEY_FIELD → This must be the table field that will be used to correlate with the lookup key. The name can be different than the lookup key field as long as the data type coincide and the values it contains are potential matches (username-user). The absence of matches will return null and a different data type will return an error when running the query .
TIMESTAMP FIELD → This must be the table timestamp that will be used to correlate with the lookup timestamp. A data type other than timestamp will return an error when running the query.
Example
We want to enrich the siem.logtrust.web.activity table with all the information about the working model in each city. If we want to work more comfortably, we can isolate the data we’re interested in by using filter and grouping operations. Then, we will use this upload lookup that contains info about company offices and the Historical lookup: retrieve json (hlurjson) operation.
These are the arguments needed when using the interface :
Lookup name: Historical_company_offices
Key: city
Time: eventdate
Complete example with screenshot of the arguments when development is in a more mature stage.
This is the syntax needed when using LINQ free-text query:
from siem.logtrust.web.activity
where isnotnull(city)
where not isempty(city)
where result = "OK"
group every 1h by city, result, region
select hlurjson("Historical_company_offices", city, eventdate)
The table timestamp will be matched with the closest previous lookup timestamp and the values in the entire lookup row will be brought into our table when the values in the city field and those in the lookup key field match. When they do not match, null will be returned.
Complete example with screenshot of the result when development is in a more mature stage.