Check the top_hits aggregation results to see if every top hit has a field with a specific value

Elastic Stack Elasticsearch
1

I am trying to accomplish what seems like it should be super easy and obviously possible but hitting a hard brick wall instead.

  1. aggregate all elastic documents in a specific index from the last 60 days into buckets by a field within the document (not a problem).

GET /slot10info-*/_search
{
"query": {
"bool": {
"filter": [
{
"range": {
"@timestamp": {
"gt": "now-60d"
}
}
}
]
}
},
"size": 0,
"aggs" : {
"all_locos" : {
"terms" : {
"field" : "Vehicle.keyword",
"size" : 500
},
.
.
.

  1. get the top 5 hits WRT time in descending order and only keep two fields from each document. (not a problem).

.
.
.
"aggs": {
"top_date_hit": {
"top_hits": {
"sort": [
{
"Vehicle.Time": {
"order": "desc"
}
}
],
"_source": {
"includes": [ "ATT.PPP Status", "VZW.PPP Status" ]
},
"size" : 5
}
},
}
}
}
}

  1. I want to look at the "ATT.PPP Status" and "VZW.PPP Status" fields respective values OF THESE 5 TOP HITS ONLY, and see if they match, "PPP Link is down".

NOTE:
elasticsearch version: 5.6.9
I have tried for days to figure out how to simply give me a list of "Vehicle" bucket whose last 5 documents have the value in "PPP link is down" in either of the fields listed above. Please let me know if I left off anything important.

2

In short, it's not possible because top_hits are a last-minute enrichment of the results. E.g. they are collected at the very end after everything else is done, and they are collecting the raw _source JSON data not the internal indexed data. So the values being returned are essentially a string blob to Elasticsearch and there's no way to process it at the moment.

top_hits are mainly for enriching search results in the UI, not for actual logic or processing.

Is there a reason you can't put the "PPP Link is down" criteria in the query itself, using a term or match query?

3

@polyfractal That's what I was afraid of and kind of read similar things in other places but I was thinking maybe there was a way around it.. maybe with a painless script or similar.

I dont filter on "PPP Link is down" because I then I want to pick out the vehicle whose modem has been offline (PPP link down) 5 times in a row.

Do you know of a different approach to aggregate an index by "Vehicle.keyword", over the last x amount of time, and finally create a list of Vehicle's whose last 5 messages have the value "PPP link is down" for either the "ATT.PPP Status" OR "VZW.PPP Status" fields?

4

This seems like one of those "last known status" type questions with the added wrinkle of state being determined by the last 5 statuses.

It's another of the behavioural-analysis questions that benefits from using an entity-centric index rather than a log-centric index (the entity in question being a vehicle).

You can build these from your log data using the new dataframes API but the tricky bit of keeping the last 5 statuses will likely require the use of custom script.

5

@Mark_Harwood, I'm guessing dataframes requires an update to a later version of either Kibana or Elasticsearch? I'm confined to 5.6 on both Elastic and Kibana. I was really hoping to do my analysis with Watcher sending off Notifications based on results to Slack... all from the handy-dandy Kibana UI :disappointed: Really don't want to spin up something on some machine to query, analyze, alert but It's starting to appear like that's my only option.

6

Here’s the old way of doing it https://twitter.com/elasticmark/status/1009380268409610240?s=21

7

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