how to use query/expr to diff 2 timeseries groupBy id

[Dieter Cailliau]

I have n x 2 timeseries: per id, i have 2 series: v=one and v=two.
There is 1 point per minute in each of these series (timestamp aligned).

I need a query that shows for each id, the difference (per timestamp) between the v=one and v=two series. It should output n timeseries (1 per id).

Is this the kind of problem that is to be solved with http://opentsdb.net/docs/build/html/api_http/query/exp.html ?

Below is my attempt to code this. Unfortunately this does not give me the right answer.

{
   "time": {
       "start": 1493596800,
       "end": 1493683200,
       "aggregator":"none"
   },
   "filters": [
       {
           "tags": [
               {
                   "type": "literal_or",
                   "tagk": "v",
                   "filter": "one",
                   "groupBy": false
               },
               {
                   "type": "wildcard",
                   "tagk": "id",
                   "filter": "*",
                   "groupBy": true
               }
           ],
           "id": "v1"
       },
       {
           "tags": [
               {
                   "type": "literal_or",
                   "tagk": "v",
                   "filter": "two",
                   "groupBy": false
               },
               {
                   "type": "wildcard",
                   "tagk": "id",
                   "filter": "*",
                   "groupBy": true
               }
           ],
           "id": "v2"
       }
   ],
   "metrics": [
       {
           "id": "v1",
           "metric": "x",
           "filter": "v1"
       },
       {
           "id": "v2",
           "metric": "x",
           "filter": "v2"
       }
   ],
   "expressions": [
       {
           "id": "delta",
           "expr": "v1-v2"
       }
      
    ],
    "outputs":[
      {"id":"delta", "alias":"delta"}
    ]
 }

[ManOLamancha]

On Thursday, September 14, 2017 at 3:41:46 AM UTC-7, Dieter Cailliau wrote:

I have n x 2 timeseries: per id, i have 2 series: v=one and v=two.
There is 1 point per minute in each of these series (timestamp aligned).

I need a query that shows for each id, the difference (per timestamp) between the v=one and v=two series. It should output n timeseries (1 per id).

Is this the kind of problem that is to be solved with http://opentsdb.net/docs/build/html/api_http/query/exp.html ?

Below is my attempt to code this. Unfortunately this does not give me the right answer.

Ah it almost works. The problem is that right now it joins across tags and since you're querying the same metric but with one tag being different, it won't join properly. I've addressed this in version 3 but I need to back-port a fix to 2.5 that will allow for explicit joins to solve your issue. 

[ga...@ridezum.com]

Is there any update to this? Did you mean 2.5? We're just on 2.4 now, any chance there's a back-port for 2.4? If not, I'm willing to do it, with some knowledge transfer.