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  1. ZABBIX FEATURE REQUESTS
  2. ZBXNEXT-1083

New type of parameter for trigger functions - %num for N-th previous value.

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    Description

      Goals:
      1. Divide a different meaning of #num parameter for different trigger functions.
      2. Add new required feature. For instance - a regexp function for previous or N-th value (single value !).

      Explanation:
      1. Currently without an experience and without looking to documentation its not clear (IMO) what parameter #num means: number of values or N-th previous value.
      For some trigger functions it's intuitively not hard to understand which is the meaning of #num.
      For instance for the "max()" it's of course number of values, and for the "last()" it's of course N-th previous value.
      But try to guess the meaning of the "#num" for the function regexp() or str() WITHOT looking to documentation. Not easy? Yes?

      2. I would like to use regexp() function for for previous or Nth value (single value !) as I said at the start. How I can do that? Yes, at the moment - is no way.
      Additional point of view - at the moment in the trigger expression we can "compare" with N-th historical value of NUMERICAL data using the last(#num) function but we cannot do the same for TEXT data. The function regexp(search,%2) would help to do that.

      Resume:
      I would suggest leave to use hash mark # for the number of values.
      And use new symbol % for N-th previous value.

      In this case less count of functions will change type of used parameter, other functions will add support of "%num". For instance regexp() will support both #num and %num.
      Functions which should use new parameter type %: last, strlen.
      Functions which should additionally support new parameter type %: logeventid, logseverity, logsource, iregexp, regexp, str.

      The mark:
      Currently: # - used, @ - global regexp, $ - macros. So it seems the mark % is free and could be suitable, but another ones could be used too (like ! or & or ^)

      Linked issue ZBX-4541

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            Unassigned Unassigned
            zalex_ua Oleksii Zagorskyi
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