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Marc-André Bombeck
f5d259db58
Windowed slope, r2 and population sd still ran a live REGR_*/STDDEV_POP query over the raw measurements partition on every warm-rollup request, because the per-bucket mean cannot reconstruct an OLS regression over the raw points in a window. The per-bucket sd/slope/r2 columns are a within-bucket fold and do not compose linearly across DAY buckets. Add the four regression-accumulator sums Postgres folds for REGR_* / STDDEV_POP - sum_x, sum_xy, sum_xx, sum_yy - per (user, type, granularity, bucketStart, source) over the same canonical-source rows the live query reads, with the x-axis in epoch days. With n = count and sum_y = mean*count already stored, all six terms are additive across buckets, so a 7/30/90-day slope/r2/sd composes from the summed accumulators with a bit-identical result to the live closed form. Migration 0190 adds the four nullable columns; nullable keeps it additive so existing rows read NULL until the boot re-fold refills them (mirrors the v1.4.39 sum_value rollout). The populator emits the four SUM terms inside the existing aggregate (no extra round-trip) and persistRollupRows writes them. composeRegression / composeWindowedRegression evaluate the closed form from already-collapsed buckets and return a full miss when any in-window bucket lacks accumulators, so the reader falls back to live SQL rather than composing a partial window.