Summary

Currently functionality of trigger expressions is not sufficient for all use cases, we must extend it.

Acceptance

1. Functionality of trigger expressions and trigger functions must be extended to support:

1. 1. Operators
      1. IN
      2. BETWEEN
      3. Modulo or Reminder (%)
   2. Aggregate functions
      1. COUNT(DISTINCT)
      2. FIRST
      3. KURTOSIS
      4. MAD
      5. SKEWNESS
      6. STDDEV_POP
      7. STDDEV_SAMP
      8. SUM_OF_SQUARES
      9. VAR_POP
      10. VAR_SAMP
   3. Mathematical functions
      1. ABS
      2. CBRT
      3. CEIL/CEILING
      4. E
      5. EXP
      6. EXPM1
      7. FLOOR
      8. LOG
      9. LOG10
      10. PI
      11. POWER
      12. RANDOM/RAND
      13. ROUND
      14. SIGN/SIGNUM
      15. SQRT
      16. TRUNCATE/TRUNC
      17. ACOS
      18. ASIN
      19. ATAN
      20. ATAN2
      21. COS
      22. COSH
      23. COT
      24. DEGREES
      25. RADIANS
      26. SIN
      27. SINH
      28. TAN
   4. String functions
      1. ASCII
      2. BIT_LENGTH
      3. CHAR
      4. CHAR_LENGTH
      5. CONCAT
      6. INSERT
      7. LCASE
      8. LEFT
      9. LENGTH
      10. LOCATE
      11. LTRIM
      12. OCTET_LENGTH
      13. POSITION
      14. REPEAT
      15. REPLACE
      16. RIGHT
      17. RTRIM
      18. SPACE
      19. SUBSTRING
      20. TRIM
      21. UCASE
   5. Bit functions and/or operators
2. The list above must be reviewed to exclude functionality we already support and obsolete functionality

1. 1. Duplicate functions that may perform same operations should be excluded in order to minimize number of supported functions (and thus complexity)
2. A better naming must be proposed to match Zabbix naming convention