Aggregate functions
Supported aggregates are COUNT, SUM, AVG, MIN, MAX, COLLECT_LIST, STDDEV_POP, STDDEV_SAMP, PERCENTILE_CONT and PERCENTILE_DISC. ALL and DISTINCT select whether duplicate input values contribute.
MATCH (p:Person)RETURN COUNT(*) AS people, AVG(p.age) AS average_age, MIN(p.age) AS youngest, MAX(p.age) AS oldest;COUNT(*) counts rows. COUNT(value) and COUNT(element) omit nulls. All aggregates omit null inputs. An empty global group produces COUNT = 0, COLLECT_LIST = [] and null numeric results. COLLECT_LIST order is unspecified.
Integer SUM accumulates in a wider representation before a checked Int64 conversion. Non-finite floating results are errors. Use GROUP BY and HAVING to form and filter groups.
MATCH (p:Person)RETURN PERCENTILE_CONT(p.age, 0.5) AS median, PERCENTILE_DISC(p.age, 0.5) AS discrete_median;The fraction must be a row-independent numeric expression in [0, 1]; a null fraction returns null. Continuous percentiles return Float64. Discrete percentiles preserve the input numeric type, including the exact selected integer.