InfluxDB: Flux - String comparison

In this example I show you how to compare a tag [string] against another tag [string] in Flux.

Example:

• We have to tags (VMName, vNICName)
• We want to compare theses tags -> strings.compare(v: r.<tag1>, t: r.<tag2>)
• And show only rows that these tags not matched

import "strings"

from(bucket: "<YOUR_BUCKET>")
  |> range(start: v.timeRangeStart, stop: v.timeRangeStop)
  |> filter(fn: (r) => 
    r._measurement == "hyperv_vmnet" and
    r._field == "Bytes_Received_persec" and 
    exists r.VMName //Exclude Hyper-V NICs 
  )
  |> last()
  |> group() //group to one table because "strings.compare" does not support multiple series
  |> unique(column: "VMName")
  // compare VMName and vNICName
  |> map(fn: (r) => ({r with 
      comparison: strings.compare(v: strings.toUpper(v: r.VMName), t: strings.toUpper(v: r.vNICName))
  }))
  |> map(fn: (r) => ({r with 
      IsCloned: 
        if r.comparison == 0 then "not cloned"
        else "yes"
  }))
  |> filter(fn: (r) => r.comparison != 0) // filter only cloned VMs
  |> keep(columns: ["_time", "VMName", "vNICName", "IsCloned"])

-> The second map() is not needed. I only use the second map to create a new field named "IsCloned".

More information's about the compare function: https://docs.influxdata.com/flux/v0.x/stdlib/strings/compare/