Aggregation Functions

Aggregation functions are used in stats, timechart, eventstats, and streamstats.

count

Count the number of events.

| stats count
| stats count AS total_events
| stats count(field)                    -- count non-null values
| stats count(eval(status>=500)) AS errors  -- conditional count

sum

Sum of numeric field values.

| stats sum(bytes) AS total_bytes by source

avg

Average (mean) of numeric field values.

| stats avg(duration_ms) AS avg_latency by endpoint

min / max

Minimum and maximum values.

| stats min(duration_ms) AS fastest, max(duration_ms) AS slowest by uri

dc (Distinct Count)

Count of unique values.

| stats dc(user_id) AS unique_users by endpoint
| stats dc(source) AS source_count

values

List of distinct values (returned as a multivalue field).

| stats values(level) AS seen_levels by source

stdev

Standard deviation.

| stats stdev(duration_ms) AS latency_stddev by endpoint

Percentiles

Compute percentile values: perc50, perc75, perc90, perc95, perc99.

| stats perc50(duration_ms) AS median,
        perc95(duration_ms) AS p95,
        perc99(duration_ms) AS p99
  by endpoint

perc50 is the median. Percentiles use the t-digest algorithm for memory-efficient approximate computation.

earliest / latest

First and last values by _time.

| stats earliest(status) AS first_status, latest(status) AS last_status by host

Conditional Aggregation

Use eval() inside count or other functions for conditional aggregation:

| stats count AS total,
        count(eval(status>=500)) AS errors,
        count(eval(status>=200 AND status<300)) AS success
  by uri
| eval error_rate = round(errors/total*100, 1)

Summary Table

Function	Description	Example
count	Count events	count, count(field), count(eval(...))
sum(f)	Sum values	sum(bytes)
avg(f)	Average	avg(duration_ms)
min(f)	Minimum	min(duration_ms)
max(f)	Maximum	max(duration_ms)
dc(f)	Distinct count	dc(user_id)
values(f)	Distinct values list	values(level)
stdev(f)	Standard deviation	stdev(duration_ms)
perc50(f)	Median (50th pct)	perc50(duration_ms)
perc75(f)	75th percentile	perc75(duration_ms)
perc90(f)	90th percentile	perc90(duration_ms)
perc95(f)	95th percentile	perc95(duration_ms)
perc99(f)	99th percentile	perc99(duration_ms)
earliest(f)	First by time	earliest(status)
latest(f)	Last by time	latest(status)