OPAL Aggregate Functions

Aggregate functions are used with aggregating verbs like timechart, aggregate, and statsby.

Aggregate functions accept multiple input values from a set of input rows and emit one output value as a single output row. For example, sum calculates the sum of all input numbers, and max returns the largest value.

Function	Description
any	Return any value of one column across a group
any_not_null	Return any non-null value of one column across a group.
array_agg	Returns an array of concatenated input values.
array_agg_distinct	Returns an array of distinct input values.
avg	Calculate the arithmetic average of the input expression across the group.
count	Count the number of non-null items in the group.
count_distinct	Estimate the approximate number of distinct values in the input using hyper-log-log.
count_distinct_exact	Count the exact number of distinct values in the input using complete enumeration (slower than [count_distinct](.
deriv	Calculate the average per-second derivative of the argument across the group.
first	Return the first value of one column across an ordered group.
first_not_null	Return the first non-null value of one column across an ordered group.
last	Return the last value of one column across an ordered group.
last_not_null	Return the last non-null value of one column across an ordered group.
max	Compute the maximum of one column across a group (with one argument) or the scalar greatest value of its arguments (with more than
median	Return the fast approximate median value of one column.
median_exact	Return the exact median value of one column.
min	Compute the minimum of one column across a group (with one argument) or the scalar least value of its arguments (with more than
object_agg	Returns one OBJECT per group.
percentile	Returns an approximated value for the specified percentile of the input expression across the group.
percentile_cont	Assuming a continuous distribution, it returns the value for the specified percentile of the input expression across the group.
percentile_disc	Assuming a discrete distribution, it returns the value for the specified percentile of the input expression across the group.
prom_quantile	prom_quantile calculates an approximate percentile value based on the distribution in a histogram metric that was generated by a
rate	Calculate the average per-second rate of the argument across the group.
stddev	Calculate the standard deviation across the group.
string_agg	Returns concatenated input values, separated by the delimiter.
string_agg_distinct	Returns concatenated input values, separated by the delimiter.
sum	Calculate the sum of the argument across the group, or of the scalar arguments if more than one.