Alternative to ActiveRelationResource which does not produce extra DB queries

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• I've searched for an existing issue.
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Description

One thing that changed significantly in 0.10 is the introduction of ActiveRelationResource, which seems to be a nice optimization to have when caching is utilized. But when caching is not turned on it actually doubles the amount of DB queries needed to process a request. For example, typical request with include would look something like this in the log on 0.10.x:

DEBUG -- :    (0.0ms)  SELECT "users"."id" AS "users_id", "users"."id" FROM "users" ORDER BY users.id asc LIMIT ? OFFSET ?  [["LIMIT", 10], ["OFFSET", 0]]
DEBUG -- :    (0.1ms)  SELECT DISTINCT users.id AS "source_id", "profiles"."id" AS "profiles_id", "profiles"."id" FROM "users" INNER JOIN "profiles" ON "profiles"."user_id" = "users"."id" WHERE "users"."id" IN (?, ?, ?) ORDER BY profiles.id asc  [["id", 1], ["id", 2], ["id", 3]]
DEBUG -- :    (0.0ms)  SELECT DISTINCT users.id AS "source_id", "posts"."id" AS "posts_id", "posts"."id" FROM "users" INNER JOIN "posts" ON "posts"."user_id" = "users"."id" WHERE "users"."id" IN (?, ?, ?) ORDER BY posts.id asc  [["id", 1], ["id", 2], ["id", 3]]
DEBUG -- :   User Load (0.0ms)  SELECT "users".* FROM "users" WHERE "users"."id" IN (?, ?, ?)  [["id", 1], ["id", 2], ["id", 3]]
DEBUG -- :   Profile Load (0.0ms)  SELECT "profiles".* FROM "profiles" WHERE "profiles"."id" IN (?, ?, ?)  [["id", 1], ["id", 2], ["id", 3]]
DEBUG -- :   Post Load (0.0ms)  SELECT "posts".* FROM "posts" WHERE "posts"."id" IN (?, ?, ?, ?, ?, ?, ?, ?, ?)  [["id", 1], ["id", 2], ["id", 3], ["id", 4], ["id", 5], ["id", 6], ["id", 7], ["id", 8], ["id", 9]]
DEBUG -- :    (0.0ms)  SELECT COUNT(*) FROM "users"

Compare to the same request on 0.9:

DEBUG -- :   User Load (0.0ms)  SELECT "users".* FROM "users" ORDER BY "users"."id" ASC LIMIT ? OFFSET ?  [["LIMIT", 10], ["OFFSET", 0]]
DEBUG -- :   Profile Load (0.1ms)  SELECT "profiles".* FROM "profiles" WHERE "profiles"."user_id" IN (?, ?, ?)  [["user_id", 1], ["user_id", 2], ["user_id", 3]]
DEBUG -- :   Post Load (0.0ms)  SELECT "posts".* FROM "posts" WHERE "posts"."user_id" IN (?, ?, ?)  [["user_id", 1], ["user_id", 2], ["user_id", 3]]
DEBUG -- :    (0.0ms)  SELECT COUNT(*) FROM "users"

Is there a plan to optimize non-cached scenario? Like having an alternative base resource that I'd behave more or less like 0.9 behaved? Thanks.

Comienza rastreando la ruta sin caché de ActiveRelationResource para las solicitudes con include y compárala con los registros de consultas de 0.9 y 0.10 que se muestran aquí. Se considera terminado cuando una alternativa u optimización evita las consultas adicionales de relación e id sin usar caché, preservando los registros incluidos y el comportamiento de la paginación.