Aggregate functions

This page describes the available functions to assist with performing aggregate calculations.

avg

avg(value) calculates simple average of values ignoring missing data (e.g null values).

Arguments:

• value is any numeric value.

Return value:

Return value type is double.

Examples:

Average transaction amount

SELECT avg(amount) FROM transactions;

avg
22.4

Average transaction amount by payment_type

SELECT payment_type, avg(amount) FROM transactions;

cash_or_card	avg
cash	22.1
card	27.4
null	18.02

count

count() or count(*) - counts rows irrespective of underlying data.

Arguments:

• count does not require arguments.

Return value:

Return value type is long.

Examples:

• Count of rows in the transactions table.

SELECT count() FROM transactions;

count
100

• Count of rows in the transactions table aggregated by payment_type value.

SELECT payment_type, count() FROM transactions;

cash_or_card	count
cash	25
card	70
null	5

note

null values are aggregated with count().

count_distinct

count_distinct(column_name) - counts distinct values in string, symbol, long256, long, or int columns.

Return value:

Return value type is long.

Examples:

• Count of distinct sides in the transactions table. Side column can either be BUY or SELL or null

SELECT count_distinct(side) FROM transactions;

count_distinct
2

• Count of distinct counterparties in the transactions table aggregated by payment_type value.

SELECT payment_type, count_distinct(counterparty) FROM transactions;

cash_or_card	count_distinct
cash	3
card	23
null	5

note

null values are not counted in the count_distinct function.

first/last

• first(column_name) - returns the first value of a column.
• last(column_name) - returns the last value of a column.

Supported column datatype: double, float, integer, character, short, byte, timestamp, date, long, geohash.

If a table has a designated timestamp, then the first row is always the row with the lowest timestamp (oldest) and the last row is always the one with the highest (latest) timestamp. For a table without a designated timestamp column, first returns the first row and last returns the last inserted row, regardless of any timestamp column.

Return value:

Return value type is string.

Examples:

Given a table sensors, which has a designated timestamp column:

device_id	temperature	ts
arduino-01	12	2021-06-02T14:33:19.970258Z
arduino-02	10	2021-06-02T14:33:21.703934Z
arduino-03	18	2021-06-02T14:33:23.707013Z

The following query returns oldest value for the device_id column:

SELECT first(device_id) FROM sensors;

first
arduino-01

The following query returns the latest symbol value for the device_id column:

SELECT last(device_id) FROM sensors;

last
arduino-03

Without selecting a designated timestamp column, the table may be unordered and the query may return different result. Given an unordered table sensors_unordered:

device_id	temperature	ts
arduino-01	12	2021-06-02T14:33:19.970258Z
arduino-03	18	2021-06-02T14:33:23.707013Z
arduino-02	10	2021-06-02T14:33:21.703934Z

The following query returns the first record for the device_id column:

SELECT first(device_id) FROM sensors_unordered;

first
arduino-01

The following query returns the last record for the device_id column:

SELECT last(device_id) FROM sensors_unordered;

last
arduino-02

haversine_dist_deg

haversine_dist_deg(lat, lon, ts) - calculates the traveled distance for a series of latitude and longitude points.

Arguments:

• lat is the latitude expressed as degrees in decimal format (double)
• lon is the longitude expressed as degrees in decimal format (double)
• ts is the timestamp for the data point

Return value:

Return value type is double.

Examples:

Calculate the aggregate traveled distance for each car_id

SELECT car_id, haversine_dist_deg(lat, lon, k)

FROM table rides

ksum

ksum(value) - adds values ignoring missing data (e.g null values). Values are added using the

Kahan compensated sum algorithm. This is only beneficial for floating-point values such as float or double.

Arguments:

• value is any numeric value.

Return value:

Return value type is the same as the type of the argument.

Examples:

SELECT ksum(a)

FROM (SELECT rnd_double() a FROM long_sequence(100));

ksum
52.79143968514029

max

max(value) - returns the highest value ignoring missing data (e.g null values).

Arguments:

• value is any numeric value

Return value:

Return value type is the same as the type of the argument.

Examples:

Highest transaction amount

SELECT max(amount) FROM transactions;

max
55.3

Highest transaction amount by payment_type

SELECT payment_type, max(amount) FROM transactions;

cash_or_card	amount
cash	31.5
card	55.3
null	29.2

min

min(value) - returns the lowest value ignoring missing data (e.g null values).

Arguments:

• value is any numeric value

Return value:

Return value type is the same as the type of the argument.

Examples:

Lowest transaction amount

SELECT min(amount) FROM transactions;

min
12.5

Lowest transaction amount, by payment_type

SELECT payment_type, min(amount) FROM transactions;

cash_or_card	min
cash	12.5
card	15.3
null	22.2

nsum

nsum(value) - adds values ignoring missing data (e.g null values). Values are added using the Neumaier sum algorithm. This is only beneficial for floating-point values such as float or double.

Arguments:

• value is any numeric value.

Return value:

Return value type is double.

Examples:

SELECT nsum(a)

FROM (SELECT rnd_double() a FROM long_sequence(100));

nsum
49.5442334742831

stddev_samp

stddev_samp(value) - calculates the sample standard deviation of values ignoring missing data (e.g null values).

Arguments:

• value is any numeric value.

Return value:

Return value type is double.

Examples:

SELECT stddev_samp(x)

FROM (SELECT x FROM long_sequence(100));

stddev_samp
29.011491975882

sum

sum(value) - adds values ignoring missing data (e.g null values).

Arguments:

• value is any numeric value.

Return value:

Return value type is the same as the type of the argument.

Examples:

Sum all quantities in the transactions table

SELECT sum(quantity) FROM transactions;

sum
100

Sum all quantities in the transactions table, aggregated by item

SELECT item, sum(quantity) FROM transactions;

item	count
apple	53
orange	47

Overflow

sum does not perform overflow check. To avoid overflow, you can cast the argument to wider type.

Cast as long to avoid overflow

SELECT sum(cast(a AS LONG)) FROM table;