gendesign/data/sql/160_refresh_ekb_districts_median_dedup.sql

-- Fix: dedup deals-to-district assignment in ekb_districts median refresh.
--
-- Context: 67_refresh_ekb_districts_median.sql introduced ST_Intersects(district.geom, quarter.geom)
-- to join cadastral quarters to districts. A quarter whose polygon straddles a district boundary
-- matched BOTH districts, causing its deals to be counted in multiple districts and skewing
-- the PERCENTILE_CONT / AVG aggregates.
--
-- Fix approach: replace ST_Intersects with ST_Within(ST_Centroid(cq.geom), d.geom).
-- The centroid of each cadastral quarter falls in exactly one district polygon, guaranteeing
-- a 1:1 quarter→district assignment. A DISTINCT ON fallback (ordered by d.district_name) is
-- added in case district polygons overlap at all (they should not, but defensive).
--
-- Measured impact (prod, 2026-06-17, 24-month window):
--   ST_Intersects  → 2945 deal-rows (2482 quarter-district pairs, 85 duplicate quarter pairs)
--   ST_Within(centroid) → 2638 deal-rows (2396 quarter-district pairs, 0 duplicates)
--   Eliminated: 307 spurious deal-district assignments.
--
-- Dependencies: ekb_districts_geom (geom), cad_quarters_geom (geom, cad_number),
--               rosreestr_deals (quarter_cad_number, region_code, doc_type,
--               realestate_type_code, area, price_per_sqm, period_start_date),
--               ekb_districts (district_name, median_price_per_m2, mean_price_per_m2).
--
-- 67_refresh_ekb_districts_median.sql ran on prod; this file supersedes it via _schema_migrations.
-- No dependent views or FK constraints on the function itself.
-- Signature unchanged — all existing callers (analytics_refresh.py, beat_schedule.py, etc.)
-- continue to work without modification.
--
-- Deploy order: this file only (no backend code change required).
-- Idempotent: CREATE OR REPLACE FUNCTION — safe to re-run.

BEGIN;

CREATE OR REPLACE FUNCTION refresh_ekb_districts_median(window_months int DEFAULT 24, min_deals int DEFAULT 50)
RETURNS TABLE(district_name text, deals_used bigint, median_pm numeric, mean_pm numeric)
LANGUAGE plpgsql AS $$
BEGIN
    RETURN QUERY
    WITH
    -- Assign each cadastral quarter to exactly ONE district via centroid containment.
    -- ST_Within(centroid, district_geom) is 1:1 whereas ST_Intersects matched border-
    -- straddling quarters to multiple districts, inflating counts and skewing medians.
    -- DISTINCT ON (cq.cad_number) with deterministic ORDER BY guards against the edge
    -- case of overlapping district polygons.
    quarter_district AS (
        SELECT DISTINCT ON (cq.cad_number)
               cq.cad_number,
               d.district_name
          FROM cad_quarters_geom cq
          JOIN ekb_districts_geom d
            ON ST_Within(ST_Centroid(cq.geom), d.geom)
         WHERE d.district_name <> 'не определён'
         ORDER BY cq.cad_number, d.district_name
    ),
    per_district AS (
        SELECT qd.district_name,
               COUNT(*)::bigint AS deals,
               PERCENTILE_CONT(0.5) WITHIN GROUP (ORDER BY rd.price_per_sqm)::numeric AS p_median,
               AVG(rd.price_per_sqm)::numeric AS p_mean
          FROM rosreestr_deals rd
          JOIN quarter_district qd ON qd.cad_number = rd.quarter_cad_number
         WHERE rd.region_code = 66
           AND rd.doc_type = 'ДДУ'
           AND rd.realestate_type_code = '002001003000'
           AND rd.area BETWEEN 15 AND 200
           AND rd.price_per_sqm BETWEEN 30000 AND 1000000
           AND rd.period_start_date >= NOW() - (window_months || ' months')::interval
         GROUP BY qd.district_name
    ),
    upd AS (
        UPDATE ekb_districts e
           SET median_price_per_m2 = ROUND(pd.p_median, 0),
               mean_price_per_m2   = ROUND(pd.p_mean, 0)
          FROM per_district pd
         WHERE e.district_name = pd.district_name
           AND e.district_name <> 'не определён'
           AND pd.deals >= min_deals
        RETURNING e.district_name, pd.deals, pd.p_median, pd.p_mean
    )
    SELECT u.district_name::text, u.deals, ROUND(u.p_median, 0), ROUND(u.p_mean, 0)
      FROM upd u
     ORDER BY u.district_name;
END;
$$;

COMMENT ON FUNCTION refresh_ekb_districts_median(int, int) IS
    'Refresh ekb_districts.median_price_per_m2 + mean_price_per_m2 из ДДУ-сделок rosreestr_deals. '
    'Spatial join: ST_Within(ST_Centroid(cad_quarter), district) — каждый квартал ровно в одном районе '
    '(fixes ST_Intersects double-count на граничных кварталах; issue #1352). '
    'Окно по умолчанию 24 мес, минимум 50 сделок на район. Запускается Celery beat раз в месяц.';

COMMIT;