Ted Dunning created DRILL-202:
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Summary: Implement average and standard deviation functions
Key: DRILL-202
URL: https://issues.apache.org/jira/browse/DRILL-202
Project: Apache Drill
Issue Type: Bug
Reporter: Ted Dunning
I need several statistical functions including average. To be complete, I
would like to implement several of the statistical functions from Postgres:
{code}
Function Argument Type Return Type Description
avg(expression) smallint, int, bigint, real, double precision, numeric, or
interval numeric for any integer-type argument, double precision for a
floating-point argument, otherwise the same as the argument data type the
average (arithmetic mean) of all input values
max(expression) any array, numeric, string, or date/time type same as
argument type maximum value of expression across all input values
min(expression) any array, numeric, string, or date/time type same as
argument type minimum value of expression across all input values
stddev(expression) smallint, int, bigint, real, double precision, or
numeric double precision for floating-point arguments, otherwise numeric
historical alias for stddev_samp
stddev_pop(expression) smallint, int, bigint, real, double precision, or
numeric double precision for floating-point arguments, otherwise numeric
population standard deviation of the input values
stddev_samp(expression) smallint, int, bigint, real, double precision, or
numeric double precision for floating-point arguments, otherwise numeric
sample standard deviation of the input values
variance(expression) smallint, int, bigint, real, double precision, or
numeric double precision for floating-point arguments, otherwise numeric
historical alias for var_samp
var_pop(expression) smallint, int, bigint, real, double precision, or
numeric double precision for floating-point arguments, otherwise numeric
population variance of the input values (square of the population
standard deviation)
var_samp(expression) smallint, int, bigint, real, double precision, or
numeric double precision for floating-point arguments, otherwise numeric
sample variance of the input values (square of the sample standard
deviation)
{code}
I plan to put these in with sum.
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