Flux: Check string within stored set/array

InfluxDB 2
,
1

I’m wondering if there’s any way to filter an input string based on a set stored in influxdb2.
e.g: here’s the (Java) entity that is being stored in influxdb2

@Measurement(name = "blah_blah")
public class EntityName {
    ...
    @Column(timestamp = true)
    private Instant time;
    @Column(tag = true)
    private Set<String> tags;
}

The goal here is to filter based on tags, say if any stored record contains a tag: “tag1”. Based on my limited knowledge of flux, I was thinking of using contains but seems that it’s not working:

|> filter(fn: (r) => contains(value: "tag1", set: r["tags"]))

error:

 runtime error @8:6-8:64: filter: type conflict: [string] != string

I guess the reason is that r[“tags”] is being treated as a string, thus I tried to pass it to array function, but it also doesn’t work.

Thanks in advance.

2

Hi @nima,

thanks for using our client.

As you said, this configuration causes that the tags are saved as a string. The corresponding LineProtocol looks like: blah_blah,tags=[tag1\,\ tag2] value=6i 1643897137.

You have to separate your tags to string fields:

    @Measurement(name = "blah_blah")
    public class EntityName {
        @Column(timestamp = true)
        private Instant time;
        @Column(tag = true)
        private String tagA;
        @Column(tag = true)
        private String tagB;
        @Column
        private long value;
    }

and then your Flux queries will looks like:

|> filter(fn: (r) => contains(value: "tag1", set: [r["tagA"], r["tagB"]]))

Regards

3

Hi @bednar
Thanks for the quick reply.

I think it’s not possible, since field: tags here will have variable length & might accept different values, say, an entity might have 2 tags & another one might contain 10 tags. Is there any way to search for array fields in influxdb2 ?

4

What do you think by tag? Is it a structure corresponding to the definition of InfluxDB’s tag: key-value - location=north,type=production,state=ready? Or is it just values like - north, production, ready?

5

Sorry, I should have thought that the name could be misleading. It’s definitely not the influxdb tag, but just random set of string values as you mentioned (second option) received by user

6

So, I’m guessing there’s no way to achieve this (searching for a term within a saved array of values) in InfluxDB (since the array itself is being stored as string?). If I"m mistaken, please let me know.
Regards.

7

What about encode the tags to something like: ##tag1##tag2##tag3## and then use |> filter(fn: (r) => contains(value: "##tag2##", set: r["tags"]))?