MobilityDB 1.1
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◆ Span_joinsel()
Join selectivity for spans. The selectivity is the ratio of the number of rows we think will be returned divided the maximum number of rows the join could possibly return (the full combinatoric join), that is joinsel = estimated_nrows / (totalrows1 * totalrows2) This function is inspired from function eqjoinsel in file selfuncs.c |