Aggregate Functions

Arroyo’s Aggregate function implementations are based on Apache DataFusion and these docs are derived from the DataFusion function reference.

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General

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avg

Returns the average of numeric values in the specified column.

avg(expression)

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

Aliases

• mean

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bit_and

Computes the bitwise AND of all non-null input values.

bit_and(expression)

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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bit_or

Computes the bitwise OR of all non-null input values.

bit_or(expression)

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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bit_xor

Computes the bitwise exclusive OR of all non-null input values.

bit_xor(expression)

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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bool_and

Returns true if all non-null input values are true, otherwise false.

bool_and(expression)

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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bool_or

Returns true if any non-null input value is true, otherwise false.

bool_or(expression)

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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count

Returns the number of rows in the specified column.

Count includes null values in the total count. To exclude null values from the total count, include <column> IS NOT NULL in the WHERE clause.

count(expression)

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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max

Returns the maximum value in the specified column.

max(expression)

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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mean

Alias of avg.

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median

Returns the median value in the specified column.

median(expression)

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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min

Returns the minimum value in the specified column.

min(expression)

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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sum

Returns the sum of all values in the specified column.

sum(expression)

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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array_agg

Returns an array created from the expression elements. If ordering requirement is given, elements are inserted in the order of required ordering.

array_agg(expression [ORDER BY expression])

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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first_value

Returns the first element in an aggregation group according to the requested ordering. If no ordering is given, returns an arbitrary element from the group.

first_value(expression [ORDER BY expression])

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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last_value

Returns the last element in an aggregation group according to the requested ordering. If no ordering is given, returns an arbitrary element from the group.

last_value(expression [ORDER BY expression])

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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Statistical

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corr

Returns the coefficient of correlation between two numeric values.

corr(expression1, expression2)

Arguments

• expression1: First expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.
• expression2: Second expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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covar

Returns the covariance of a set of number pairs.

covar(expression1, expression2)

Arguments

• expression1: First expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.
• expression2: Second expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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covar_pop

Returns the population covariance of a set of number pairs.

covar_pop(expression1, expression2)

Arguments

• expression1: First expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.
• expression2: Second expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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covar_samp

Returns the sample covariance of a set of number pairs.

covar_samp(expression1, expression2)

Arguments

• expression1: First expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.
• expression2: Second expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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stddev

Returns the standard deviation of a set of numbers.

stddev(expression)

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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stddev_pop

Returns the population standard deviation of a set of numbers.

stddev_pop(expression)

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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stddev_samp

Returns the sample standard deviation of a set of numbers.

stddev_samp(expression)

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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var

Returns the statistical variance of a set of numbers.

var(expression)

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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var_pop

Returns the statistical population variance of a set of numbers.

var_pop(expression)

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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var_samp

Returns the statistical sample variance of a set of numbers.

var_samp(expression)

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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regr_slope

Returns the slope of the linear regression line for non-null pairs in aggregate columns. Given input column Y and X: regr_slope(Y, X) returns the slope (k in Y = k*X + b) using minimal RSS fitting.

regr_slope(expression1, expression2)

Arguments

• expression_y: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.
• expression_x: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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regr_avgx

Computes the average of the independent variable (input) expression_x for the non-null paired data points.

regr_avgx(expression_y, expression_x)

Arguments

• expression_y: Dependent variable. Can be a constant, column, or function, and any combination of arithmetic operators.
• expression_x: Independent variable. Can be a constant, column, or function, and any combination of arithmetic operators.

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regr_avgy

Computes the average of the dependent variable (output) expression_y for the non-null paired data points.

regr_avgy(expression_y, expression_x)

Arguments

• expression_y: Dependent variable. Can be a constant, column, or function, and any combination of arithmetic operators.
• expression_x: Independent variable. Can be a constant, column, or function, and any combination of arithmetic operators.

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regr_count

Counts the number of non-null paired data points.

regr_count(expression_y, expression_x)

Arguments

• expression_y: Dependent variable. Can be a constant, column, or function, and any combination of arithmetic operators.
• expression_x: Independent variable. Can be a constant, column, or function, and any combination of arithmetic operators.

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regr_intercept

Computes the y-intercept of the linear regression line. For the equation (y = kx + b), this function returns b.

regr_intercept(expression_y, expression_x)

Arguments

• expression_y: Dependent variable. Can be a constant, column, or function, and any combination of arithmetic operators.
• expression_x: Independent variable. Can be a constant, column, or function, and any combination of arithmetic operators.

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regr_r2

Computes the square of the correlation coefficient between the independent and dependent variables.

regr_r2(expression_y, expression_x)

Arguments

• expression_y: Dependent variable. Can be a constant, column, or function, and any combination of arithmetic operators.
• expression_x: Independent variable. Can be a constant, column, or function, and any combination of arithmetic operators.

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regr_sxx

Computes the sum of squares of the independent variable.

regr_sxx(expression_y, expression_x)

Arguments

• expression_y: Dependent variable. Can be a constant, column, or function, and any combination of arithmetic operators.
• expression_x: Independent variable. Can be a constant, column, or function, and any combination of arithmetic operators.

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regr_syy

Computes the sum of squares of the dependent variable.

regr_syy(expression_y, expression_x)

Arguments

• expression_y: Dependent variable. Can be a constant, column, or function, and any combination of arithmetic operators.
• expression_x: Independent variable. Can be a constant, column, or function, and any combination of arithmetic operators.

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regr_sxy

Computes the sum of products of paired data points.

regr_sxy(expression_y, expression_x)

Arguments

• expression_y: Dependent variable. Can be a constant, column, or function, and any combination of arithmetic operators.
• expression_x: Independent variable. Can be a constant, column, or function, and any combination of arithmetic operators.

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Approximate

• approx_distinct
• approx_median
• approx_percentile_cont
• approx_percentile_cont_with_weight

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approx_distinct

Returns the approximate number of distinct input values calculated using the HyperLogLog algorithm.

approx_distinct(expression)

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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approx_median

Returns the approximate median (50th percentile) of input values. It is an alias of approx_percentile_cont(x, 0.5).

approx_median(expression)

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

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approx_percentile_cont

Returns the approximate percentile of input values using the t-digest algorithm.

approx_percentile_cont(expression, percentile, centroids)

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.

• percentile: Percentile to compute. Must be a float value between 0 and 1 (inclusive).

• centroids: Number of centroids to use in the t-digest algorithm. Default is 100.

  If there are this number or fewer unique values, you can expect an exact result. A higher number of centroids results in a more accurate approximation, but requires more memory to compute.

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approx_percentile_cont_with_weight

Returns the weighted approximate percentile of input values using the t-digest algorithm.

approx_percentile_cont_with_weight(expression, weight, percentile)

Arguments

• expression: Expression to operate on. Can be a constant, column, or function, and any combination of arithmetic operators.
• weight: Expression to use as weight. Can be a constant, column, or function, and any combination of arithmetic operators.
• percentile: Percentile to compute. Must be a float value between 0 and 1 (inclusive).