A little related bonus :
when doing the time-join,
the next step is to interpolate to have a more accurate estimation :
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DROP FUNCTION IF EXISTS range_interpolate(nr anyrange,obs anyelement) ;
CREATE OR REPLACE FUNCTION range_interpolate(nr anyrange,obs anyelement)
RETURNS TABLE(lower_weight NUMERIC,upper_weight NUMERIC)
AS $$
--@param a range
--@param an observation (value) of the same type as the range
--@return the weight to apply to lower bound and upper bound of range to get the value.
--exceptions : -inf or +inf : weight of the bound is 0, the other 1.
--exceptions : range = a point : returns weight of 0.5 for each bound (they are identical but the asociated data may not be)
SELECT
CASE WHEN upper(nr)=lower(nr) THEN ROW(0.5,0.5)
--WHEN obs=lower(nr) AND obs=upper(nr) THEN ARRAY[0.5,0.5]
--THEN (obs-lower(nr))/ra, (upper(nr)-obs)/ra
WHEN lower_inf(nr)=TRUE OR lower(nr) IS NULL THEN ROW(0,1)
WHEN upper_inf(nr)=TRUE OR upper(nr) IS NULL THEN ROW(1,0)
ELSE ROW( (upper(nr)-obs)/(upper(nr)-lower(nr)),(obs-lower(nr))/(upper(nr)-lower(nr)))
END
--testing :
--SELECT * FROM range_interpolate(numrange(1,10) , round(10,2))
$$
LANGUAGE SQL
IMMUTABLE
RETURNS NULL ON NULL INPUT;
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