Durchführen eines großen Updates mit mehreren Tabellen in PostgreSQL

Diese Abfrage sollte die gleichen Ergebnisse liefern, vermeidet aber den CASE

-- EXPLAIN ANALYZE
UPDATE table_a a
SET rebuilding_costs = drie.rebuilding_costs
FROM (
        SELECT COALESCE(b.address, c.address, d.address) AS address
        , COALESCE(b.rebuilding_costs, c.rebuilding_costs,  d.rebuilding_costs)
            AS rebuilding_costs
        FROM table_b b
        FULL OUTER JOIN table_c c ON c.address = b.address
                AND  c.rebuilding_costs BETWEEN 200001 AND 400000
        FULL OUTER JOIN table_D d ON d.address = b.address
                AND  d.rebuilding_costs BETWEEN 400001 AND 600000
        WHERE b.rebuilding_costs BETWEEN 100001 AND 200000
        ) drie
WHERE a.address = drie.address
AND a.rebuilding_costs <> drie.rebuilding_costs -- Avoid useless updates
        ;

UPDATE:Ein ähnlicher Ansatz, basierend auf einem verketteten Satz von CTEs:

-- --------------------------------
EXPLAIN ANALYZE
WITH cte_b AS (
        SELECT b.address,  b.rebuilding_costs
        FROM table_b b
        WHERE b.rebuilding_costs BETWEEN 100001 AND 200000
        )
,       cte_c AS (
        SELECT c.address , c.rebuilding_costs
        FROM table_c c
        WHERE  c.rebuilding_costs BETWEEN 200001 AND 400000
        AND NOT EXISTS (SELECT * FROM cte_b WHERE cte_b.address = c.address)
        )
,       cte_d AS (
        SELECT d.address , d.rebuilding_costs
        FROM table_d d
        WHERE  d.rebuilding_costs BETWEEN 400001 AND 600000
        AND NOT EXISTS (SELECT * FROM cte_b WHERE cte_b.address = d.address)
        AND NOT EXISTS (SELECT * FROM cte_c WHERE cte_c.address = d.address)
        )
,       cte_bcd AS (
        SELECT           cte_b.address,  cte_b.rebuilding_costs FROM cte_b
        UNION ALL SELECT cte_c.address,  cte_c.rebuilding_costs FROM cte_c
        UNION ALL SELECT cte_d.address,  cte_d.rebuilding_costs FROM cte_d
        )
UPDATE table_a a
SET rebuilding_costs = cte_bcd.rebuilding_costs
FROM cte_bcd
WHERE a.address = cte_bcd.address
-- avoid useless updates this way:
AND a.rebuilding_costs <> cte_bcd.rebuilding_costs
-- ,or this way:
-- AND cte_bcd.rebuilding_costs IS DISTINCT FROM a.rebuilding_costs
   ;

UPDATE2:CTEs können langsam sein, da sie als Optimierungsbarrieren wirken. Eine Quick&Dirty-Methode besteht darin, tem als (temporäre) VIEWs umzuschreiben und stattdessen auf diese zu verweisen. Dadurch kann der Optimierer die verschiedenen Teile der Abfrage in und aus Unterabfragen verschieben und diese sogar kombinieren und wiederverwenden.

CREATE TEMP VIEW cte_b AS (
        SELECT b.address,  b.rebuilding_costs
        FROM table_b b
        WHERE b.rebuilding_costs BETWEEN 100001 AND 200000
        );
CREATE TEMP VIEW        cte_c AS (
        SELECT c.address , c.rebuilding_costs
        FROM table_c c
        WHERE  c.rebuilding_costs BETWEEN 200001 AND 400000
        AND NOT EXISTS (SELECT * FROM cte_b WHERE cte_b.address = c.address)
        );
CREATE TEMP VIEW        cte_d AS (
        SELECT d.address , d.rebuilding_costs
        FROM table_d d
        WHERE  d.rebuilding_costs BETWEEN 400001 AND 600000
        AND NOT EXISTS (SELECT * FROM cte_b WHERE cte_b.address = d.address)
        AND NOT EXISTS (SELECT * FROM cte_c WHERE cte_c.address = d.address)
        );
CREATE TEMP VIEW        cte_bcd AS (
        SELECT           cte_b.address,  cte_b.rebuilding_costs FROM cte_b
        UNION ALL SELECT cte_c.address,  cte_c.rebuilding_costs FROM cte_c
        UNION ALL SELECT cte_d.address,  cte_d.rebuilding_costs FROM cte_d
        );
EXPLAIN -- ANALYZE
UPDATE table_a a
SET rebuilding_costs = cte_bcd.rebuilding_costs
FROM cte_bcd
WHERE a.address = cte_bcd.address
AND a.rebuilding_costs <> cte_bcd.rebuilding_costs -- avoid useless updates
-- AND a.address < 100000
        ;