i have an issue with influxdb query.
when I query normally:
SELECT "distance" FROM "testdb"."autogen"."laserdistance" WHERE time > timeA AND time < timeB
I will get back all the data without error.
if I query with either mean() or median():
SELECT mean("distance") AS "mean_distance" FROM "testdb"."autogen"."laserdistance" WHERE time > timeA AND time < timeB GROUP BY time(some_interval) FILL(null)
I will sure get back some null value in a very inconsistent pattern(sometime a lot, sometime not so much).
I understand that FILL(null) is the one responsible for the null issue to fill in the interval that don't have value.
is there a way to get the nearest value instead of fill it with null?
Use FILL(linear):
linear - Reports the results of linear interpolation for time intervals with no data.
Doc: https://docs.influxdata.com/influxdb/v1.7/query_language/data_exploration/#group-by-time-intervals-and-fill
Related
I am trying to find the timestamp of the first occurrence of max value(the cursor point in below image)
I wrote query
min(timestamp(max(jmeter_count_total{label="GET - Company Updates - ua_users_company-updates"})))
But it's returning the max timestamp of the max value
I am not able to grab the value highlighted by cursor in below image(minimum value). Instead I am getting highest value when I use above query.
I've played with this for a bit and I think this may work (take it with a grain of salt, due to limited testing).
TLDR - the query (using only foo for brevity):
min_over_time((timestamp(foo) and (foo == scalar(max_over_time(foo[2h]))))[1h:])
This portion of the query:
foo == scalar(max_over_time(foo[2h]))
returns only values where foo matches the max value of foo in the last 2h interval. For retrieving the timestamp of those cases we use the timestamp function and use these previous clause as a conditional:
timestamp(foo) and (foo == scalar(max_over_time(foo[2h])))
Finally we only want to get the first/lowest timestamp value over the time window, which is what the outer min_over_time with the nested subquery should do.
I fiddled with the online Prometheus demo using one of the metrics present there. You can check the queries here.
Let me know how can I solve or write query in influx for this scenario ( flux or influx query will work for me )
I have a field called x and m. There is a function in influx called difference which takes the difference between the first and the next field value.
I would like to take the difference between x and next x value and also would like to have the next m value as the row
so this is what I require as a single row
(x_next - x), m_next
.....
How can I do that in influx of flux queries. I can have x_next-x using difference but how to get m_next in this.
select difference(x), moving_average(m)+0.5*difference(m) from mydata
is the closest solution you can use without group by time.
I'd like to calculate the delta values for a series of measurements stored in an InfluxDB. The values are readings from an electricity meter taken every 5 minutes. The values increase over time. Here is subset of the data to give you an idea (commands shown below are executed in the InfluxDB CLI):
> SELECT "Haushaltstromzaehler - cnt" FROM "myhome_measurements" WHERE time >= '2018-02-02T10:00:00Z' AND time < '2018-02-02T11:00:00Z'
name: myhome_measurements
time Haushaltstromzaehler - cnt
---- --------------------------
2018-02-02T10:00:12.610811904Z 11725.638
2018-02-02T10:05:11.242021888Z 11725.673
2018-02-02T10:10:10.689827072Z 11725.707
2018-02-02T10:15:12.143326976Z 11725.736
2018-02-02T10:20:10.753357056Z 11725.768
2018-02-02T10:25:11.18448512Z 11725.803
2018-02-02T10:30:12.922032896Z 11725.837
2018-02-02T10:35:10.618788096Z 11725.867
2018-02-02T10:40:11.820355072Z 11725.9
2018-02-02T10:45:11.634203904Z 11725.928
2018-02-02T10:50:11.10436096Z 11725.95
2018-02-02T10:55:10.753853952Z 11725.973
Calculating the differences in the InfluxDB CLI is pretty straightforward with the difference() function. This gives me the electricity consumed within the 5 minutes intervals:
> SELECT difference("Haushaltstromzaehler - cnt") FROM "myhome_measurements" WHERE time >= '2018-02-02T10:00:00Z' AND time < '2018-02-02T11:00:00Z'
name: myhome_measurements
time difference
---- ----------
2018-02-02T10:05:11.242021888Z 0.03499999999985448
2018-02-02T10:10:10.689827072Z 0.033999999999650754
2018-02-02T10:15:12.143326976Z 0.02900000000045111
2018-02-02T10:20:10.753357056Z 0.0319999999992433
2018-02-02T10:25:11.18448512Z 0.03499999999985448
2018-02-02T10:30:12.922032896Z 0.033999999999650754
2018-02-02T10:35:10.618788096Z 0.030000000000654836
2018-02-02T10:40:11.820355072Z 0.03299999999944703
2018-02-02T10:45:11.634203904Z 0.028000000000247383
2018-02-02T10:50:11.10436096Z 0.02200000000084401
2018-02-02T10:55:10.753853952Z 0.02299999999922875
Where I struggle is getting this to work in a continuous query. Here is the command I used to setup the continuous query:
CREATE CONTINUOUS QUERY cq_Haushaltstromzaehler_cnt ON myhomedb
BEGIN
SELECT difference(sum("Haushaltstromzaehler - cnt")) AS "delta" INTO "Haushaltstromzaehler_delta" FROM "myhome_measurements" GROUP BY time(1h)
END
Looking in the InfluxDB log file I see that no data is written in the new 'delta' measurement from the continuous query execution:
...finished continuous query cq_Haushaltstromzaehler_cnt, 0 points(s) written...
After much troubleshooting and experimenting I now understand why no data is generated. Setting up a continuous query requires to use the GROUP BY time() statement. This in turn requires to use an aggregate function within the differences() function. The problem now is that the aggregate function returns only one value for the time period specified by GROUP BY time(). Obviously, the differences() function cannot calculate a difference from just one value. Essentially, continuous query executes a command like this:
> SELECT difference(sum("Haushaltstromzaehler - cnt")) FROM "myhome_measurements" WHERE time >= '2018-02-02T10:00:00Z' AND time < '2018-02-02T11:00:00Z' GROUP BY time(1h)
>
I'm now somewhat clueless as to how to make this work and appreciate any advice you might have.
Does it help using the last aggregate function? Not tested this as a cq yet.
Select difference(last(T1_Consumed)) AS T1_Delta, difference(last(T2_Consumed)) AS T2_Delta
from P1Data
where time >= 1551648871000000000 group by time(1h)
DIFFERENCE() would calculate delta from the "aggregated" value taken from previous group, not within current group.
So fill free to use selector function there - since your counters seemed to be cumulative, LAST() should be working well.
I have a following issue:
I need to calculate difference between consecutive points where some arbitrary ID is equal. The following:
SELECT difference(value_field) FROM mesurementName WHERE "IdField" = '10'
Works, returns difference between each consecutive point with IdField BUT IdField is lost (only time is propagated to query result). In my case time is not unique (i.e. measurement may contain many points with same timestamp, but different IdField). So I tried:
SELECT difference(value_field), IdField FROM mesurementName WHERE "IdField" = '10'
which yields:
error parsing query: mixing aggregate and non-aggregate queries is not supported!!
My next attempt was using sub-query:
SELECT IdField, diff
FROM (
SELECT
difference(flow_val) as diff
FROM
mesurementA
WHERE "IdField" = '10'
)
Which resulted in always null value in IdField.
I'd like to ask you for help or suggestion how to solve issue. By the way, we are using InfluxDB 1.3, which is not supporting JOIN anymore
If anyone would stuck as I was, then solution is following:
SELECT difference(value_field) FROM mesurementName GROUP BY "IdField"
Above somehow implicitly add "IdField" to result series and is propagated to resulting measurements with INTO clause
I have a slightly complex time arithmetic problem.
I have a reminder system where the user can set "how many x before event" duration. For example: If I set '5 minutes' - I need to get reminder before 5 minutes of the event schedule.
In my reminder system, I have a cron which runs every minute and sends reminder mails. So far so good. I want to find all calendar events which are eligible for reminder (calendar entry whose scheduled time is between "5.minutes.from_now and 6.minutes.from_now"
I am trying the write the following where clause :
conds = "'when' >= '#{eval("#{cal.remind_before.to_s}.#{cal.remind_before_what.downcase}.from_now").to_s(:db)}' AND 'when' < '#{eval("#{cal.remind_before.to_s}.#{cal.remind_before_what.downcase}.from_now + 1.minutes").to_s(:db)}'"
#mail_calendar_for_reminder= Calendar.find(:all, :conditions=> conds)
Here cal.reminder_before = '5', cal.remind_before_what.downcase='minutes'
so the eval would be evaluating (5.minutes.from_now) and (6.minutes.from_now)
The resulting SQL statement is :
SELECT "calendars".* FROM "calendars" WHERE ('when' >= '2011-01-11 14:44:54' AND 'when' < '2011-01-11 14:45:54')
This SQL is syntactically and logically correct because it gets a time range of 5.minutes.from_now and 6.minutes.from_now. But it is not selecting eligible records. I suspect two things:
1. The SQL above is doing string comparisons rather than time comparisons.
2. The database entry for calendar's scheduled time has the following format :
2011-01-11 14:45:09.000000 --the 0's the end might be messing teh date comparisons.
I tried almost all sorts of date range arithmetic but could not get the eligible records in this query.
Depending on your server and its load, a one-minute window for cron might be a little optimistic.
What happens if you login to the dbms server and execute that SQL statement? Any rows returned? Any error messages?
You can try an explicit type cast. So
'when' >= CAST('2011-01-11 14:44:54' AS DATETIME) ...
Your dbms might require a different syntax for type casting and conversion. Search your docs.
Are your column names case sensitive? Is the column 'when' or 'When'? (Or wHen?)
This query returns your test event. Note the double quotes around the column name.
SELECT "calendars".*
FROM "calendars"
WHERE ("when" >= '2011-01-10 15:56'
AND "when" < '2011-01-10 15:57')