Zabbix Documentation 4.4

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manual:config:items:itemtypes:calculated

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manual:config:items:itemtypes:calculated [2016/08/29 15:09]
andris [7.2 Configurable fields]
manual:config:items:itemtypes:calculated [2019/04/02 06:04] (current)
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-==== - #7 Calculated items ====+==== 7 Calculated items ====
  
-=== Overview ===+=== Overview ===
  
 With calculated items you can create calculations on the basis of other items. With calculated items you can create calculations on the basis of other items.
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 To use calculated items, choose the item type **Calculated**. ​ To use calculated items, choose the item type **Calculated**. ​
  
-=== Configurable fields ===+=== Configurable fields ===
  
 The **key** is a unique item identifier (per host). You can create any key name using supported symbols. The **key** is a unique item identifier (per host). You can create any key name using supported symbols.
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 |**func** ​        |One of the [[manual:​appendix:​triggers:​functions|functions]] supported in trigger expressions:​ last, min, max, avg, count, etc| |**func** ​        |One of the [[manual:​appendix:​triggers:​functions|functions]] supported in trigger expressions:​ last, min, max, avg, count, etc|
 |**key** ​    |The key of another item whose data you want to use. It may be defined as **key** or **hostname:​key**.\\ //Note:// Putting the whole key in double quotes ("​..."​) is strongly recommended to avoid incorrect parsing because of spaces or commas within the key.\\ If there are also quoted parameters within the key, those double quotes must be escaped by using the backslash (\). See **Example 5** below.| |**key** ​    |The key of another item whose data you want to use. It may be defined as **key** or **hostname:​key**.\\ //Note:// Putting the whole key in double quotes ("​..."​) is strongly recommended to avoid incorrect parsing because of spaces or commas within the key.\\ If there are also quoted parameters within the key, those double quotes must be escaped by using the backslash (\). See **Example 5** below.|
-|**parameter(s)** |Any additional parameters that may be required.|+|**parameter(s)** |Function parameter(s),​ if required.|
  
 <note tip>All items that are referenced from the calculated item formula must exist and be collecting data (exceptions in [[:​manual/​appendix/​triggers/​functions#​functions_and_unsupported_items|functions and unsupported items]]). Also, if you change the item key of a referenced item, you have to manually update any formulas using that key.</​note>​ <note tip>All items that are referenced from the calculated item formula must exist and be collecting data (exceptions in [[:​manual/​appendix/​triggers/​functions#​functions_and_unsupported_items|functions and unsupported items]]). Also, if you change the item key of a referenced item, you have to manually update any formulas using that key.</​note>​
  
-<note important>​[[manual:​config:​macros:​usermacros|User macros]] in the formula will be expanded if used to reference a parameter or a constant. User macros will NOT be expanded if used to reference ​a function, host name, item key or operator.</​note>​+<note important>​[[manual:​config:​macros:​usermacros|User macros]] in the formula will be expanded if used to reference a function ​parameter or a constant. User macros will NOT be expanded if referencing ​a function, host name, item key, item key parameter ​or operator.</​note>​
  
 A more complex formula may use a combination of functions, operators and brackets. You can use all functions and [[:​manual/​config/​triggers/​expression#​operators|operators]] supported in trigger expressions. Note that the syntax is slightly different, however logic and operator precedence are exactly the same. A more complex formula may use a combination of functions, operators and brackets. You can use all functions and [[:​manual/​config/​triggers/​expression#​operators|operators]] supported in trigger expressions. Note that the syntax is slightly different, however logic and operator precedence are exactly the same.
  
 Unlike trigger expressions,​ Zabbix processes calculated items according to the item update interval, not upon receiving a new value. Unlike trigger expressions,​ Zabbix processes calculated items according to the item update interval, not upon receiving a new value.
 +
 +<​note>​If the calculation result is a float value it will be trimmed to an integer if the calculated item type of information is //Numeric (unsigned)//​.</​note>​
  
 A calculated item may become unsupported in several cases: A calculated item may become unsupported in several cases:
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 Support for calculated items was introduced in Zabbix 1.8.1.\\ Starting from Zabbix 3.2 calculated items in some cases may involve unsupported items as described in [[:​manual/​appendix/​triggers/​functions#​functions_and_unsupported_items|functions and unsupported items]], [[:​manual/​config/​triggers/​expression#​expressions_with_unsupported_items_and_unknown_values|Expressions with unsupported items and unknown values]] and [[:​manual/​config/​triggers/​expression#​operators|Operators]]. Support for calculated items was introduced in Zabbix 1.8.1.\\ Starting from Zabbix 3.2 calculated items in some cases may involve unsupported items as described in [[:​manual/​appendix/​triggers/​functions#​functions_and_unsupported_items|functions and unsupported items]], [[:​manual/​config/​triggers/​expression#​expressions_with_unsupported_items_and_unknown_values|Expressions with unsupported items and unknown values]] and [[:​manual/​config/​triggers/​expression#​operators|Operators]].
-=== Usage examples ===+ 
 +=== Usage examples ===
  
 == Example 1 == == Example 1 ==