max (windowcomp) ↗

Use the max() function within the windowcomp stage to compute the maximum value of a specified field over a window of rows. Unlike the comp stage version, the windowcomp version preserves all original rows and adds the computed maximum as a new field. This is equivalent to MAX() OVER(...) in SQL.

Syntax

| windowcomp max(<field>) [by <partition_field1>, <partition_field2>, ...] [sort [asc|desc] <sort_field1>, ...] [between <lower> [and <upper>] [frame_type=rows|range]] [as <alias>]

Parameters

Name Type Required Description
field numeric, string, or datetime Yes The field from which to compute the maximum value.
partition_field any No One or more fields to partition the data by (equivalent to SQL PARTITION BY).
sort_field any No One or more fields to define the order within each partition (equivalent to SQL ORDER BY). Defaults to ascending.
lower integer or null No Lower bound of the window frame. 0 = current row, negative = rows before, null = unbounded.
upper integer or null No Upper bound of the window frame. 0 = current row, positive = rows after, null = unbounded.
frame_type rows or range No Type of window frame. rows (default) uses physical row offsets; range uses value-based offsets on the sort field.
alias string No An alias for the output field.

Returns

Type: same as input field

Description: The max() function returns the maximum value within the defined window for each row. All original rows are preserved.

Usage notes

  • Row preservation: Unlike comp max(), the windowcomp max() does not reduce the number of rows. Each row retains its original data and gets an additional field with the window maximum.
  • No partitioning: If no by clause is specified, the window spans the entire result set.
  • Default frame: If no window frame is specified, the default frame is from the start of the partition to the current row (between null and 0).
  • Null handling: NULL values are ignored in the computation.
  • Running maximum: Can be combined with sort to compute running maximums.

Examples

Example 1: Maximum severity per host (all rows preserved)

Goal: Compute the maximum alert severity for each host while preserving all original rows.

XQL code:

dataset = xdr_data
| windowcomp max(alert_severity) by agent_hostname as max_severity_per_host

Explanation: The max() function computes the maximum alert_severity within each agent_hostname partition. All original rows are preserved, and each row receives the partition's maximum value in max_severity_per_host.

Output:

_TIME AGENT_HOSTNAME ALERT_SEVERITY MAX_SEVERITY_PER_HOST
2024-01-15 08:00:00 workstation-1 3 7
2024-01-15 09:00:00 workstation-1 7 7
2024-01-15 10:00:00 workstation-1 5 7
2024-01-15 08:30:00 workstation-2 2 4
2024-01-15 09:30:00 workstation-2 4 4

Example 2: Running maximum over time

Goal: Compute a running maximum of bytes sent, ordered by time.

XQL code:

dataset = xdr_data
| windowcomp max(bytes_sent) sort asc _time as running_max_bytes

Explanation: By sorting on _time in ascending order, the max() function computes a running maximum of bytes_sent from the start of the dataset up to the current row.

Output:

_TIME BYTES_SENT RUNNING_MAX_BYTES
2024-01-15 08:00:00 100 100
2024-01-15 09:00:00 250 250
2024-01-15 10:00:00 150 250
2024-01-15 11:00:00 300 300

Example 3: Maximum within a sliding window of 3 rows

Goal: Compute the maximum bytes sent within a sliding window of 3 rows (current row plus one row before and one row after).

XQL code:

dataset = xdr_data
| windowcomp max(bytes_sent) sort asc _time between -1 and 1 as local_max

Explanation: The between -1 and 1 clause defines a sliding window of 3 rows centered on the current row. The max() function returns the maximum bytes_sent value within that window for each row.

Output:

_TIME BYTES_SENT LOCAL_MAX
2024-01-15 08:00:00 100 250
2024-01-15 09:00:00 250 250
2024-01-15 10:00:00 150 300
2024-01-15 11:00:00 300 300