FIXME This page is not fully translated, yet. Please help completing the translation.
(remove this paragraph once the translation is finished)

4 History functions

All functions listed here are supported in:

• Trigger expressions
• Calculated items

Some general notes on function parameters:

• Function parameters are separated by a comma
• Optional function parameters (or parameter parts) are indicated by < >
• /host/key is a common mandatory first parameter for the functions referencing the host item history
• /host/key and time period:time shift parameters must never be quoted
• Function-specific parameters are described with each function

Function details

Some general notes on function parameters:

• Function parameters are separated by a comma
• Optional function parameters (or parameter parts) are indicated by < >
• Function-specific parameters are described with each function
• /host/key and (sec|#num)<:time shift> parameters must never be quoted

change(/host/key)

The amount of difference between the previous and latest value.
Supported value types: Float, Integer, String, Text, Log.
For strings returns: 0 - values are equal; 1 - values differ.

Parameters: see common parameters.

Comments:

• Numeric difference will be calculated, as seen with these incoming example values ('previous' and 'latest' value = difference):
  '1' and '5' = +4
  '3' and '1' = -2
  '0' and '-2.5' = -2.5
  
• See also: abs for comparison.

Examples:

change(/host/key)>10

changecount(/host/key,(sec|#num)<:time shift>,<mode>)

The number of changes between adjacent values within the defined evaluation period.
Supported value types: Float, Integer, String, Text, Log.

Parameters:

• See common parameters;
  
• mode (must be double-quoted) - possible values: all - count all changes (default); dec - count decreases; inc - count increases

For non-numeric value types, the mode parameter is ignored.

Examples:

changecount(/host/key,1w) #the number of value changes for the last week until now
       changecount(/host/key,#10,"inc") #the number of value increases (relative to the adjacent value) among the last 10 values
       changecount(/host/key,24h,"dec") #the number of value decreases (relative to the adjacent value) for the last 24 hours until now

count(/host/key,(sec|#num)<:time shift>,<operator>,<pattern>)

The number of values within the defined evaluation period.
Supported value types: Float, Integer, String, Text, Log.

Parameters:

• See common parameters;
  
• operator (must be double-quoted). Supported operators:
  eq - equal (default)
  ne - not equal
  gt - greater
  ge - greater or equal
  lt - less
  le - less or equal
  like - matches if contains pattern (case-sensitive)
  bitand - bitwise AND
  regexp - case-sensitive match of the regular expression given in pattern
  iregexp - case-insensitive match of the regular expression given in pattern
  
• pattern - the required pattern (string arguments must be double-quoted).

Comments:

• Float items match with the precision of 2.22e-16; if database is not upgraded the precision is 0.000001.
• With bitand as the third parameter, the fourth pattern parameter can be specified as two numbers, separated by '/': number_to_compare_with/mask. count() calculates "bitwise AND" from the value and the mask and compares the result to number_to_compare_with. If the result of "bitwise AND" is equal to number_to_compare_with, the value is counted.
  If number_to_compare_with and mask are equal, only the mask need be specified (without '/').
• With regexp or iregexp as the third parameter, the fourth pattern parameter can be an ordinary or global (starting with '@') regular expression. In case of global regular expressions case sensitivity is inherited from global regular expression settings. For the purpose of regexp matching, float values will always be represented with 4 decimal digits after '.'. Also note that for large numbers difference in decimal (stored in database) and binary (used by Zabbix server) representation may affect the 4th decimal digit.

Examples:

count(/host/key,10m) #the values for the last 10 minutes until now
       count(/host/key,10m,"like","error") #the number of values for the last 10 minutes until now that contain 'error'
       count(/host/key,10m,,12) #the number of values for the last 10 minutes until now that equal '12'
       count(/host/key,10m,"gt",12) #the number of values for the last 10 minutes until now that are over '12'
       count(/host/key,#10,"gt",12) #the number of values within the last 10 values until now that are over '12'
       count(/host/key,10m:now-1d,"gt",12) #the number of values between 24 hours and 10 minutes and 24 hours ago from now that were over '12'
       count(/host/key,10m,"bitand","6/7") #the number of values for the last 10 minutes until now having '110' (in binary) in the 3 least significant bits
       count(/host/key,10m:now-1d) #the number of values between 24 hours and 10 minutes and 24 hours ago from now

countunique(/host/key,(sec|#num)<:time shift>,<operator>,<pattern>)

The number of unique values within the defined evaluation period.
Supported value types: Float, Integer, String, Text, Log.

Parameters:

• See common parameters;
  
• operator (must be double-quoted). Supported operators:
  eq - equal (default)
  ne - not equal
  gt - greater
  ge - greater or equal
  lt - less
  le - less or equal
  like - matches if contains pattern (case-sensitive)
  bitand - bitwise AND
  regexp - case-sensitive match of the regular expression given in pattern
  iregexp - case-insensitive match of the regular expression given in pattern
  
• pattern - the required pattern (string arguments must be double-quoted).

Comments:

• Float items match with the precision of 2.22e-16; if database is not upgraded the precision is 0.000001.
• With bitand as the third parameter, the fourth pattern parameter can be specified as two numbers, separated by '/': number_to_compare_with/mask. countunique() calculates "bitwise AND" from the value and the mask and compares the result to number_to_compare_with. If the result of "bitwise AND" is equal to number_to_compare_with, the value is counted.
  If number_to_compare_with and mask are equal, only the mask need be specified (without '/').
• With regexp or iregexp as the third parameter, the fourth pattern parameter can be an ordinary or global (starting with '@') regular expression. In case of global regular expressions case sensitivity is inherited from global regular expression settings. For the purpose of regexp matching, float values will always be represented with 4 decimal digits after '.'. Also note that for large numbers difference in decimal (stored in database) and binary (used by Zabbix server) representation may affect the 4th decimal digit.

Examples:

countunique(/host/key,10m) #the number of unique values for the last 10 minutes until now
       countunique(/host/key,10m,"like","error") #the number of unique values for the last 10 minutes until now that contain 'error'
       countunique(/host/key,10m,,12) #the number of unique values for the last 10 minutes until now that equal '12'
       countunique(/host/key,10m,"gt",12) #the number of unique values for the last 10 minutes until now that are over '12'
       countunique(/host/key,#10,"gt",12) #the number of unique values within the last 10 values until now that are over '12'
       countunique(/host/key,10m:now-1d,"gt",12) #the number of unique values between 24 hours and 10 minutes and 24 hours ago from now that were over '12'
       countunique(/host/key,10m,"bitand","6/7") #the number of unique values for the last 10 minutes until now having '110' (in binary) in the 3 least significant bits
       countunique(/host/key,10m:now-1d) #the number of unique values between 24 hours and 10 minutes and 24 hours ago from now

find(/host/key,(sec|#num)<:time shift>,<operator>,<pattern>)

Find a value match within the defined evaluation period.
Supported value types: Float, Integer, String, Text, Log.
Returns: 1 - found; 0 - otherwise.

Parameters:

• See common parameters;
  
• sec or #num (optional) - defaults to the latest value if not specified
• operator (must be double-quoted). Supported operators:
  eq - equal (default)
  ne - not equal
  gt - greater
  ge - greater or equal
  lt - less
  le - less or equal
  like - matches if contains the string given in pattern (case-sensitive)
  bitand - bitwise AND
  regexp - case-sensitive match of the regular expression given in pattern
  iregexp - case-insensitive match of the regular expression given in pattern
  
• pattern - the required pattern (string arguments must be double-quoted); Perl Compatible Regular Expression (PCRE) regular expression if operator is regexp, iregexp.

Comments:

• If more than one value is processed, '1' is returned if there is at least one matching value.
• With regexp or iregexp as the third parameter, the fourth pattern parameter can be an ordinary or global (starting with '@') regular expression. In case of global regular expressions case sensitivity is inherited from the global regular expression settings.

Example:

find(/host/key,10m,"like","error") #find a value that contains 'error' within the last 10 minutes until now

first(/host/key,sec<:time shift>)

The first (the oldest) value within the defined evaluation period.
Supported value types: Float, Integer, String, Text, Log.

Parameters:

• See common parameters.

See also last().

Example:

first(/host/key,1h) #retrieve the oldest value within the last hour until now

fuzzytime(/host/key,sec)

Check how much the passive agent time differs from the Zabbix server/proxy time.
Supported value types: Float, Integer.
Returns: 1 - difference between the passive item value (as timestamp) and Zabbix server/proxy timestamp (the clock of value collection) is less than or equal to T seconds; 0 - otherwise.

Parameters:

• See common parameters.

Comments:

• Usually used with the 'system.localtime' item to check that local time is in sync with the local time of Zabbix server. Note that 'system.localtime' must be configured as a passive check.
• Can be used also with the vfs.file.time[/path/file,modify] key to check that the file did not get updates for long time;
• This function is not recommended for use in complex trigger expressions (with multiple items involved), because it may cause unexpected results (time difference will be measured with the most recent metric), e.g. in fuzzytime(/Host/system.localtime,60s)=0 or last(/Host/trap)<>0.

Example:

fuzzytime(/host/key,60s)=0 #detect a problem if the time difference is over 60 seconds

last(/host/key,<#num<:time shift>>)

The most recent value.
Supported value types: Float, Integer, String, Text, Log.

Parameters:

• See common parameters;
  
• #num (optional) - the Nth most recent value.

Comments:

• Take note that a hash-tagged time period (#N) works differently here than with many other functions. For example: last() is always equal to last(#1); last(#3) - the third most recent value (not three latest values);
• Zabbix does not guarantee the exact order of values if more than two values exist within one second in history;
• See also first().

Example:

last(/host/key) #retrieve the last value
       last(/host/key,#2) #retrieve the previous value
       last(/host/key,#1) <> last(/host/key,#2) #the last and previous values differ

logeventid(/host/key,<#num<:time shift>>,<pattern>)

Check if the event ID of the last log entry matches a regular expression.
Supported value types: Log.
Returns: 0 - does not match; 1 - matches.

Parameters:

• See common parameters;
  
• #num (optional) - the Nth most recent value;
  
• pattern (optional) - the regular expression describing the required pattern, Perl Compatible Regular Expression (PCRE) style (string arguments must be double-quoted).

logseverity(/host/key,<#num<:time shift>>)

Log severity of the last log entry.
Supported value types: Log.
Returns: 0 - default severity; N - severity (integer, useful for Windows event logs: 1 - Information, 2 - Warning, 4 - Error, 7 - Failure Audit, 8 - Success Audit, 9 - Critical, 10 - Verbose).

Parameters:

• See common parameters;
  
• #num (optional) - the Nth most recent value.

Zabbix takes log severity from the Information field of Windows event log.

logsource(/host/key,<#num<:time shift>>,<pattern>)

Check if log source of the last log entry matches a regular expression.
Supported value types: Log.
Returns: 0 - does not match; 1 - matches.

Parameters:

• See common parameters;
  
• #num (optional) - the Nth most recent value;
  
• pattern (optional) - the regular expression describing the required pattern, Perl Compatible Regular Expression (PCRE) style (string arguments must be double-quoted).

Normally used for Windows event logs.

Example:

logsource(/host/key,,"VMware Server")

monodec(/host/key,(sec|#num)<:time shift>,<mode>)

Check if there has been a monotonous decrease in values.
Supported value types: Integer.
Returns: 1 - if all elements in the time period continuously decrease; 0 - otherwise.

Parameters:

• See common parameters;
  
• mode (must be double-quoted) - weak (every value is smaller or the same as the previous one; default) or strict (every value has decreased).

Example:

monodec(/Host1/system.swap.size[all,free],60s) + monodec(/Host2/system.swap.size[all,free],60s) + monodec(/Host3/system.swap.size[all,free],60s) #calculate in how many hosts there has been a decrease in free swap size

monoinc(/host/key,(sec|#num)<:time shift>,<mode>)

Check if there has been a monotonous increase in values.
Supported value types: Integer.
Returns: 1 - if all elements in the time period continuously increase; 0 - otherwise.

Parameters:

• See common parameters;
  
• mode (must be double-quoted) - weak (every value is bigger or the same as the previous one; default) or strict (every value has increased).

Example:

monoinc(/Host1/system.localtime,#3,"strict")=0 #check if the system local time has been increasing consistently

nodata(/host/key,sec,<mode>)

Check for no data received.
Supported value types: Integer, Float, Character, Text, Log.
Returns: 1 - if no data received during the defined period of time; 0 - otherwise.

Parameters:

• See common parameters;
  
• sec - the period should not be less than 30 seconds because the history syncer process calculates this function only every 30 seconds; nodata(/host/key,0) is disallowed.
• mode - if set to strict (double-quoted), this function will be insensitive to proxy availability (see comments for details).

Comments:

• the 'nodata' triggers monitored by proxy are, by default, sensitive to proxy availability - if proxy becomes unavailable, the 'nodata' triggers will not fire immediately after a restored connection, but will skip the data for the delayed period. Note that for passive proxies suppression is activated if connection is restored more than 15 seconds and no less than 2 & ProxyUpdateFrequency seconds later. For active proxies suppression is activated if connection is restored more than 15 seconds later. To turn off sensitiveness to proxy availability, use the third parameter, e.g.: nodata(/host/key,5m,"strict"); in this case the function will fire as soon as the evaluation period (five minutes) without data has past.
  
• This function will display an error if, within the period of the 1st parameter:
  - there's no data and Zabbix server was restarted
  - there's no data and maintenance was completed
  - there's no data and the item was added or re-enabled
  
• Errors are displayed in the Info column in trigger configuration;
  
• This function may not work properly if there are time differences between Zabbix server, proxy and agent. See also: Time synchronization requirement.

percentile(/host/key,(sec|#num)<:time shift>,percentage)

The P-th percentile of a period, where P (percentage) is specified by the third parameter.
Supported value types: Float, Integer.

Parameters:

• See common parameters;
  
• percentage - a floating-point number between 0 and 100 (inclusive) with up to 4 digits after the decimal point.

rate(/host/key,sec<:time shift>)

The per-second average rate of the increase in a monotonically increasing counter within the defined time period.
Supported value types: Float, Integer.

Parameters:

• See common parameters.

Functionally corresponds to 'rate' of PromQL.

Example:

rate(/host/key,30s) #if the monotonic increase over 30 seconds is 20, this function will return 0.67.

Footnotes

¹ The function is evaluated starting with the first received value (unless the time shift parameter is used), i.e. Zabbix will not wait for all the values of the defined evaluation period before evaluating the function.