I am trying to get the latest timestamp in the index, and then searching for that time. I constructed a search to accomplish this:
* | head 1 | fields _time
However, putting this into a subsearch, does not return any events.
* [SEARCH * | head 1 | fields _time ]
_time seems to be filtered out of the subsearch results. How do I avoid this?
subsearch results always ignore internal fields (those that start with _) when constructing the outer query.
What you have to do is to set the value of a special field 'search' to contain the exact outer query string you want, i.e.
* [search * | head 1 | eval search = "_time=" . _time | fields search]
Really you could do this:
* [ search * | head 1 | eval earliest=_time | eval latest=_time | return earliest,latest ]