The correlation coefficient of the least squares fit line of the adjusted counter value and epoch value of the time column. Given that the slope of a line for any counter value must be non-negative, this must also always be non-negative and in the range from 0.0 to 1.0. It measures how well the least squares fit the available data, where a value of 1.0 represents the strongest correlation between time and the counter increasing.

corr(
summary CounterSummary
) RETURNS DOUBLE PRECISION

For more information about counter aggregation functions, see the hyperfunctions documentation.

NameTypeDescription
summaryCounterSummaryThe input CounterSummary from a counter_agg call
NameTypeDescription
corrDOUBLE PRECISIONThe correlation coefficient computed from the least squares fit of the adjusted counter values input to the CounterSummary
SELECT
id,
bucket,
corr(summary)
FROM (
SELECT
id,
time_bucket('15 min'::interval, ts) AS bucket,
counter_agg(ts, val) AS summary
FROM foo
GROUP BY id, time_bucket('15 min'::interval, ts)
) t

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