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.
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.
I was trying to write a simple FluxQL Query in Grafana Dashboard that uses a variable
m1(of type constant)(which contains the name of the measurement)
I created the variable m1 in grafana dashboard variables
m1 = my-measurement
and tried to run the following queries but non of them worked and they either say expression request error or No Data)
i.e
SELECT count("fails") FROM "/^${m1:raw}$/"
SELECT count("fails") FROM "/^${m1}$/"
SELECT count("fails") FROM $m1" (expression request error)
SELECT count("fails") FROM "$m1"
SELECT count("fails") FROM "${m1}"
The only query worked was without dashboard variables
SELECT count("fails") FROM "my-measurement"
How can I use the variables to work for that query.
On the similar ground I tried to make a custom variable(myVar) for which we take integer input values from user and on that basis where clause should work, but same error occurs either no data or expression request error
What I tried was
SELECT count(*) from "my-measurement-2" WHERE ("value" > $myVar)
How should I solve these issues?Please help
You may have a problem with
1.) syntax
SELECT count("fails")
FROM "${m1:raw}"
2.) data
You may correct query syntax, but query can be very inefficient. Query execution may need a lot of time - so it's better to have timefilter, which will use selected dashboard time range (make sure you have some data in that time range)
SELECT count("fails")
FROM "${m1:raw}"
WHERE $timeFilter
3.) Grafana panel configuration
Make sure you are using suitable panel - for query above Stat panel is a good option (that query returns only single value, not timeseries, so time series panel types may have a problem with that).
Generally, use query inspector to see how are variables interpolated - there can be "magic", which is not obvious - e.g. quotes which are added around numeric variables, so then it is string filtering and not numeric filtering on the InfluxDB level.
I've a query that uses difference function and I can't understand why it returns no data.
The query is:
SELECT
difference(FIRST(grid_power_counter)) as grid_power_consumed
FROM homesolar.origin.main GROUP BY time(15m)
If I remove the difference function it returns data:
SELECT
FIRST(grid_power_counter) as grid_power_consumed
FROM homesolar.origin.main GROUP BY time(15m)
Also, I can get results if I add a where time > now()-24h to the select with difference function.
I really can't understand that behavior. Can someone help me?
Q: My query would only work if I add the where filter to it. Why is that so?
Quoted from influxdb's Groupby time doc:
Basic GROUP BY time() queries require an InfluxQL function in the
SELECT clause and a time range in the WHERE clause.
I suspect your first DIFFERENCE query didn't work because it was missing the mandatory WHERE filter for the Groupby time(...) function.
The Group by time() clause could be returning no rows and hence not.
This could potentially be a github issue for the influx team as I think their query parser should be complaining to you about the missing where filter for Group by time.
References:
https://docs.influxdata.com/influxdb/v1.5/query_language/data_exploration/#the-group-by-clause
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
Ruby 1.9.2 / rails 3.1 / deploy onto heroku --> posgresql
Hi, Once a number of rows relating to an object goes over a certain amount, I wish to pull back every nth row instead. It's simply because the rows are used (in part) to display data for graphing, so once the number of rows returned goes above say 20, it's good to return every second one, and so forth.
This question seemed to point in the right direction:
ActiveRecord Find - Skipping Records or Getting Every Nth Record
Doing a mod on row number makes sense, but using basically:
#widgetstats = self.widgetstats.find(:all,:conditions => 'MOD(ROW_NUMBER(),3) = 0 ')
doesn't work, it returns an error:
PGError: ERROR: window function call requires an OVER clause
And any attempt to solve that with e.g. basing my OVER clause syntax on things I see in the answer on this question:
Row numbering in PostgreSQL
ends in syntax errors and I can't get a result.
Am I missing a more obvious way of efficiently returning every nth task or if I'm on the right track any pointers on the way to go? Obviously returning all the data and fixing it in rails afterwards is possible, but terribly inefficient.
Thank you!
I think you are looking for a query like this one:
SELECT * FROM (SELECT widgetstats.*, row_number() OVER () AS rownum FROM widgetstats ORDER BY id) stats WHERE mod(rownum,3) = 0
This is difficult to build using ActiveRecord, so you might be forced to do something like:
#widgetstats = self.widgetstats.find_by_sql(
%{
SELECT * FROM
(
SELECT widgetstats.*, row_number() OVER () AS rownum FROM widgetstats ORDER BY id
) AS stats
WHERE mod(rownum,3) = 0
}
)
You'll obviously want to change the ordering used and add any WHERE clauses or other modifications to suit your needs.
Were I to solve this, I would either just write the SQL myself, like the SQL that you linked to. You can do this with
my_model.connection.execute('...')
or just get the id numbers and find by id
ids = (1..30).step(2)
my_model.where(id => ids)