Getting count to work with Grafana - influxdb

I have an InfluxDB query that works:
select count("cars") from "bridge_activity" where time > now() - 1m group by count
When I enter this query into Grafana on a dashboard, nothing shows up. I've been sure to zoom out enough that the time period in question is visible.
What I'm trying to do is, keep track of the number of cars that have gone over the bridge, over the past minute. I'd like to use this as a measurement of relative activity for the bridge.
What am I doing wrong on the Grafana dashboard?

Remove the group by count if you just want a value for a singlestat panel.
If you're looking to graph the number of cars over time, then you need a query like SELECT count("cars") from "bridge_activity" GROUP BY time(1m)
https://docs.influxdata.com/influxdb/v1.0/query_language/data_exploration/#group-by-time-intervals

Related

How to measure throughput with dynamic interval in Grafana

We are measuring throughput using Grafana and Influx. Of course, we would like to measure throughput in terms how many requests, approximately, happens every single second (rps).
The typical request is:
SELECT sum("count") / 10 FROM "http_requests" GROUP BY time(10s)
But we are loosing possibility to use astonishing dynamic $__interval that very useful when graph scope is large, like a day of week. When we are changing interval we should change divider into SELECT expression.
SELECT sum("count") / $__interval FROM "http_requests" GROUP BY time($__interval)
But this approach does not work, because of empty result returns.
How to create request using dynamic $__interval for throughput measuring?
The reason you get no results is that $__interval is not a number but a string such as 10s, 1m, etc. that is understood by influxdb as a time range. So it is not possible to use it the way you are trying.
However, what you want to calculate is the mean which is available as a function in InfluxQL. The way to get the behavior that you want is with something like this.
SELECT mean("count") FROM "http_requests" GROUP BY time($__interval)
EDIT: On a second thought that is not quite what you want.
You'd probably need to use derivative. I'll come back to you on that one later.
Edit2: Do you think this answers the question that you have Calculating request per second using InfluxDB on Grafana
Edit3: Third edit's a charm.
We use your starting query and wrap it in another one as such:
SELECT sum("rps") from (SELECT sum("count") / 10 as rps FROM "http_requests" GROUP BY time(10s)) GROUP BY time($__interval)

Offsetting a graph by the first value of the shown time span

I have a graph of an energy meter in Grafana which shows the value of the consumed active energy over the selected time span.
This is a relatively new meter, a few months old, so the highest value it is currently showing is around 1570.3 kWh.
The interval shown in the image above is over the course of 24h, so it starts at 1568.1 kWh.
I want to offset the entire graph by 1568.1 kWh, so that the beginning of the graph is at 0 kWh and the end at 2200 Wh (~ 91 Wh per hour in average over 24 h).
It should always adjust when I change the selected time span, so that I can get a good overview of the daily, weekly or monthly consumption.
How do I archive this?
I read that using something like SELECT integral(derivative(max("in-value"))) ... would do the job, but I didn't get it to work. Also, I believe that just adding a SELECT max("in-value") - first_value_of_timespan("in-value") ... would be more precise and efficient, but such a method first_value_of_timespan does not exist.
The solution is to take the difference between the current interval and the next one (there are many small intervals in the shown time span), and then to do a cumulative_sum over all the differences of the time range.
In the specific case shown in the question the solution would be
SELECT cumulative_sum(difference(max("in-total"))) FROM "le.e6.haus.strom.zähler.hausstrom-solar" WHERE $timeFilter GROUP BY time($__interval) fill(previous)

influxdb group by from most recent time

Using "group by" to bin 5m intervals. The way it works now it will group from 15min to just under 20min and this will be give a 15 timestamp.
Is it possible to group from 20 to just above 15 and give it a 20 min timestamp.
thank you
Unfortunately, no: the time would always be the beginning of each time group.
I mean, you can group like that with ORDER BY time DESC - for some functions (like DIFFERENCE()) that does matter - but the timestamp still be the beginning.
That seems to be a feature of InfluxDB (although I haven't found mention of that in InfluxDB docs).
PS In Kapacitor, you can use the time of the selected point instead of the time group interval beginning - but only for selector functions, not aggregates

InfluxDB - Query milliseconds since last data point in a time series

Is it possible to write a InfluxDB query that will give me the number of milliseconds since the last entry in a time series? I'd like to add a single-stat panel in Grafana displaying how old the data is.
I don't think it is possible since you are not able to query the time alone. A influxdb query needs at least one non-time field in a query. You could workaround that by double saving the time in a extra field which you are able to query alone.
But you still want to use now() - "the extra time field". But as far as I found out you also can't use now() inside grafana.
Update: there is a [Feature-Request] now on grafanas github. Make sure to vote it up so it gets implemented one day: https://github.com/grafana/grafana/issues/6710
Update 2: The feature got finaly implemented -> See my answer here: How to show "33 minutes ago" on Grafana dashboard with InfluxDB?

InfluxDB and Grafana graph using midnight as 0 on Y-axis derivative

I am graphing with Grafana (2.6.0) and I have an InfluxDB (0.10.2) database with the following data in it:
> select * from "WattmeterMainskwh" where time > now() - 5m
name: WattmeterMainskwh
-----------------------
time value
1457579891000000000 15529.322
1457579956000000000 15529.411
1457580011000000000 15529.425
1457580072000000000 15529.460
1457580135000000000 15529.476
...etc...
This data collects my household kilowatt usage as measured by a kWH gauge that steadily increments the usage value across months or years. I cannot easily reset the counter, nor do I wish to do so.
My goal is to create a graph that shows my daily kWH use over 24 hour periods starting at midnight, or at a minimum showing relative kWH over the interval displayed. This type of graph would be useful in many other circumstances as well where I could imagine "errors across the day" or "visitors since opening time" or "BGP resets per calendar week" were useful but the collection counter was not reset to zero upon the reset or turn-over of the time interval. This kind of counting is actually quite common in my experience.
This graph works, but doesn't show me what I'm looking for:
SELECT derivative(mean("value")) FROM "WattmeterMainskwh" WHERE $timeFilter GROUP BY time($interval) fill(null)
That graph just shows the difference between one sample and the previous sample. What I want is a steadily increasing line starting from the left side of the graph and increasing towards the right side of the graph, with zero as the bottom of the Y axis, and the graph starting at zero at the farthest left X value.
This graph works too and shows me the correct curve, but it's off by fifteen thousand or so. So far, it's the closest to what I want but since this is an ever-increasing counter that can't be reset I need to subtract some from the Y axis. Ideally, I'd like to subtract whatever the value was at the previous midnight from each sample to get a relative number based on a day instead of an absolute based on all time.
SELECT sum("value") FROM "WattmeterMainskwh" WHERE $timeFilter GROUP BY time($interval) fill(null)
And here's the graph from that previous statement:
Graph that is off by 15k
This attempt didn't work - I apparently can't take a sum of a derivative group:
SELECT sum(derivative(mean("value"))) FROM "WattmeterMainskwh" WHERE $timeFilter GROUP BY time($interval) fill(null)
This doesn't work, either - I can't perform functions within "derivative":
SELECT derivative(sum("value")-first("value")) FROM "WattmeterMainskwh" WHERE $timeFilter GROUP BY time($interval) fill(null)
Of course, I could just create a new value that had calculations applied to it before I wrote it into InfluxDB, but that seems to me to be a data-redundant and sloppy way to solve this problem, as well as being quite inflexible if I want to look at other intervals on a whim. I'm hoping that there is some way to do this more elegantly within the combination of InfluxDB & Grafana, but I'm just not able to find it with the search terms I've used or the thinking I've put towards interpreting the documentation.
Is this type of graph even possible with InfluxDB/Grafana? As far as I can tell a continuous query is not a solution, and the lack of nested SELECTs makes even the hackish ways of doing this not obvious to me.
BONUS: It would be really great to have the graph show midnight every night as a "zero" location, instead of "zero" being the first point in the displayed interval, so looking at five days of normal data would show five distinct "waves" of increasing daily aggregate energy usage, with the wave Y value going back down to zero at 12:00:01 on each day. But I'll take whatever I can get.
Nested functions have only partial support. However, you can effectively nest functions by chaining Continuous Queries.
Use a CQ to calculate the derivative(mean(value)) and store that in a new measurement foo. Then for your graph you can query select sum(value) from foo.
(I know this answer is quite late, but it might help others. Oh, and please excuse me for all the Dutch in my graphs; I had to keep it in dutch for the highest possible WAF)
You could do what I do for my kWh calculations:
Which results in a simple query like this:
SELECT distinct("kwh_combined") FROM "smartmeter" WHERE $timeFilter GROUP BY time($__interval) fill(linear)
In order to get your total count.. or if you want it in a nice graph like this which shows the number of kWh's used per hour in the bars and the yellow line (I normally run in dark mode, excuse the yellow) which is my current WATT power draw:
This data (or at least your hourly usage in bars) can be retrieved by a query like this:
Which is this exact query (for B):
SELECT spread("kwh_combined") FROM "smartmeter" WHERE $timeFilter GROUP BY time(1h) fill(null)
... where the 'kwh_combined' is (still) my counter just counting up and up.
All this results in me being able to 'query' the InfluxDB for a certain time period, like "last 24 hours" to come up with a nice panel like this: (ignore the encircled prices, that was for a question I posted I just made 10 minutes ago, check my PS)
I hope this helps you or anyone else; it took me some figuring out, but I'm happy to give something back to the community :)
PS: Don't be as stupid as I was and hardcode your electrical and gas prices into your dashboard but store them with your measurements as they could change over time.
I had the same problem (same application even) and solved it here. In your case, the query should be roughly:
SELECT value-value_fill FROM
(SELECT first(value) as value_fill FROM WattmeterMainskwh WHERE time>now()-7d GROUP BY time(1d)),
(SELECT first(value) as value FROM WattmeterMainskwh WHERE time>now()-7d GROUP BY time(1h))
fill(previous)

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