Search non existent field values

#1

I see influxdb does not store null values , but is there any way to search out these non existent fields/null values

Example: we have a measurement m1 having fields f1,f2,f3

Data inserted will have some of these field values “null” at different times.

So how to find out the timestamps where f2 is null or non existent!

select * only shows blank in the proper fields, how to delete the rows with f2 as non-existent values aka null.

Any help appreciated.

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#2

To find the “null” values you can simply use the “fill” option available with group by time(5m) fill null. Here you can use the time internal as the interval between f1,f2,f3 data inserts.

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#3

Can you please give an example of your query with GROUP BY time(...) to find NULL fields?

I’m looking to find individual points that did not have a particular field set when they were inserted, and I haven’t found any way to do this since it was first suggested in April 2014 to allow checking for undefined fields.

#4

I’m not sure if it can be extracted but you can try a nested query e.g.

select bottom(sum,20) from (select sum(field) from measurement where tagvalue=“tag” group by time(5m) fill(0))