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Early access 1.6.0 Calculate the slope of the linear least-squares fit for a gauge aggregate. The dependent variable is the gauge value, and the independent variable is time. Time is always in seconds, so the slope estimates the per-second rate of change. This gives a result similar to rate, but it can more accurately reflect the usual gauge behavior in the presence of infrequent, abnormally large changes.

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Arguments

NameTypeDefaultRequiredDescription
summaryGaugeSummary-✔A gauge aggregate created using gauge_agg

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Returns

DOUBLE PRECISION: The slope of the linear least-squares fit

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Samples

Calculate the gauge slope per id and per 15-minute interval. 
SELECT
    id,
    bucket,
    slope(summary)
FROM (
    SELECT
        id,
        time_bucket('15 min'::interval, ts) AS bucket,
        gauge_agg(ts, val) AS summary
    FROM foo
    GROUP BY id, time_bucket('15 min'::interval, ts)
) t