The array_length function in APL (Axiom Processing Language) returns the length of an array. You can use this function to analyze and filter data by array size, such as identifying log entries with specific numbers of entries or events with multiple tags. This function is useful for analyzing structured data fields that contain arrays, such as lists of error codes, tags, or IP addresses.

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For users of other query languages

If you come from other query languages, this section explains how to adjust your existing queries to achieve the same results in APL.

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Usage

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Syntax

array_length(array_expression)

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Parameters

  • array_expression: An expression representing the array to measure.

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Returns

The function returns an integer representing the number of elements in the specified array.

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Use case example

In OpenTelemetry traces, array_length can reveal the number of events associated with a span.

Query

['otel-demo-traces']
| take 50
| extend event_count = array_length(events)
| where event_count > 2

Run in Playground

Output

_timetrace_idspan_idservice.nameevent_count
2024-10-28T12:30:00trace_abc123span_001frontend3

This query finds spans associated with at least three events.

  • array_slice: Extracts a subset of elements from an array.
  • array_concat: Combines multiple arrays.
  • array_shift_left: Shifts array elements one position to the left, moving the first element to the last position.