Join i wolne sortowanie

CREATE TABLE "offers"(
    "offerId" SERIAL PRIMARY KEY,
    "name" varchar(128) NOT NULL,
    ...);

CREATE TABLE "termins"(
    "terminId" SERIAL PRIMARY KEY,
    "offerId" int NOT NULL REFERENCES "offers" ON DELETE CASCADE ON UPDATE CASCADE,
    "dateFrom" date NOT NULL,
    "price" numeric NOT NULL,
    ...);

SELECT
    *
FROM
    (
    SELECT
        DISTINCT ON("offerId") te."terminId", te."dateFrom", te."price", te."offerId"
    FROM
        termins te
    WHERE
        "dateFrom" > now()
    ORDER BY
        "offerId", "price"
    ) t
INNER JOIN
    "offers" o ON(o."offerId" = t."offerId")
LIMIT 10

Limit  (cost=0.00..42.10 rows=10 width=187)

  ->  Merge Left Join  (cost=0.00..10348.97 rows=2458 width=187)

        Merge Cond: (te."offerId" = o."offerId")

        ->  Unique  (cost=0.00..9002.22 rows=2458 width=44)

              ->  Index Scan using "offerId_price_idx" on termins te  (cost=0.00..8722.18 rows=112013 width=44)

                    Filter: ("dateFrom" > now())

        ->  Index Scan using offers_pkey on offers o  (cost=0.00..1274.61 rows=6735 width=143)

SELECT
    *
FROM
    (
    SELECT
        DISTINCT ON("offerId") te."terminId", te."dateFrom", te."price", te."offerId"
    FROM
        termins te
    WHERE
        "dateFrom" > now()
    ORDER BY
        "offerId", "price"
    ) t
INNER JOIN
    "offers" o ON(o."offerId" = t."offerId")
ORDER BY
    "price"
LIMIT 10

Limit  (cost=9863.39..9863.42 rows=10 width=187)

  ->  Sort  (cost=9863.39..9869.54 rows=2458 width=187)

        Sort Key: te.price

        ->  Hash Left Join  (cost=562.54..9810.27 rows=2458 width=187)

              Hash Cond: (te."offerId" = o."offerId")

              ->  Unique  (cost=0.00..9002.21 rows=2458 width=44)

                    ->  Index Scan using "offerId_price_idx" on termins te  (cost=0.00..8722.18 rows=112012 width=44)

                          Filter: ("dateFrom" > now())

              ->  Hash  (cost=339.35..339.35 rows=6735 width=143)

                    ->  Seq Scan on offers o  (cost=0.00..339.35 rows=6735 width=143)