gpudb::AggregateStatisticsResponse Struct Reference

A set of output parameters for const. More...

#include <gpudb/protocol/aggregate_statistics.h>

Public Member Functions
	AggregateStatisticsResponse ()
	Constructs an AggregateStatisticsResponse object with default parameter values. More...

Public Attributes
std::map< std::string, double >	stats
std::map< std::string, std::string >	info

Detailed Description

A set of output parameters for const.

Calculates the requested statistics of the given column(s) in a given table.

The available statistics are count (number of total objects), mean, stdv (standard deviation), variance, skew, kurtosis, sum, min, max, weighted_average, cardinality (unique count), estimated_cardinality, percentile and percentile_rank.

Estimated cardinality is calculated by using the hyperloglog approximation technique.

Percentiles and percentile ranks are approximate and are calculated using the t-digest algorithm. They must include the desired percentile/percentile_rank. To compute multiple percentiles each value must be specified separately (i.e. 'percentile(75.0),percentile(99.0),percentile_rank(1234.56),percentile_rank(-5)').

A second, comma-separated value can be added to the percentile statistic to calculate percentile resolution, e.g., a 50th percentile with 200 resolution would be 'percentile(50,200)'.

The weighted average statistic requires a weight_column_name to be specified in options. The weighted average is then defined as the sum of the products of columnName times the weight_column_name values divided by the sum of the weight_column_name values.

Additional columns can be used in the calculation of statistics via the additional_column_names option. Values in these columns will be included in the overall aggregate calculation–individual aggregates will not be calculated per additional column. For instance, requesting the count & mean of columnName x and additional_column_names y & z, where x holds the numbers 1-10, y holds 11-20, and z holds 21-30, would return the total number of x, y, & z values (30), and the single average value across all x, y, & z values (15.5).

The response includes a list of key/value pairs of each statistic requested and its corresponding value.

Definition at line 260 of file aggregate_statistics.h.

Constructor & Destructor Documentation

gpudb::AggregateStatisticsResponse::AggregateStatisticsResponse ( )

inline

Constructs an AggregateStatisticsResponse object with default parameter values.

Definition at line 267 of file aggregate_statistics.h.

Member Data Documentation

std::map<std::string, std::string> gpudb::AggregateStatisticsResponse::info

Definition at line 274 of file aggregate_statistics.h.

std::map<std::string, double> gpudb::AggregateStatisticsResponse::stats

Definition at line 273 of file aggregate_statistics.h.

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The documentation for this struct was generated from the following file:

• gpudb/protocol/aggregate_statistics.h