小编Gar*_*ett的帖子

此查询获取您关注的人创建的帖子列表。您可以关注无限数量的人，但大多数人关注 < 1000 人。

使用这种查询方式，明显的优化是缓存"Post"id，但不幸的是我现在没有时间这样做。

EXPLAIN ANALYZE SELECT
    "Post"."id",
    "Post"."actionId",
    "Post"."commentCount",
    ...
FROM
    "Posts" AS "Post"
INNER JOIN "Users" AS "user" ON "Post"."userId" = "user"."id"
LEFT OUTER JOIN "ActivityLogs" AS "activityLog" ON "Post"."activityLogId" = "activityLog"."id"
LEFT OUTER JOIN "WeightLogs" AS "weightLog" ON "Post"."weightLogId" = "weightLog"."id"
LEFT OUTER JOIN "Workouts" AS "workout" ON "Post"."workoutId" = "workout"."id"
LEFT OUTER JOIN "WorkoutLogs" AS "workoutLog" ON "Post"."workoutLogId" = "workoutLog"."id"
LEFT OUTER JOIN "Workouts" AS "workoutLog.workout" ON "workoutLog"."workoutId" = "workoutLog.workout"."id"
WHERE
"Post"."userId" IN …

我有一个包含 2 个反连接（UserEmails = 1M+ 行和Subscriptions = <100k 行）、2 个条件和一个排序的查询。我为2个条件+排序创建了索引，这将查询速度提高了50%。两个反连接都有索引。但是，查询太慢（生产时 4 秒）。

这是查询：

SELECT
    "Users"."firstName",
    "Users"."lastName",
    "Users"."email",
    "Users"."id"
FROM
    "Users"
WHERE
    NOT EXISTS (
        SELECT
            1
        FROM
            "UserEmails"
        WHERE
            "UserEmails"."userId" = "Users". ID
    )
AND NOT EXISTS (
    SELECT
        1
    FROM
        "Subscriptions"
    WHERE
        "Subscriptions"."userId" = "Users". ID
)
AND "isEmailVerified" = TRUE
AND "emailUnsubscribeDate" IS NULL
ORDER BY
    "Users"."createdAt" DESC
LIMIT 100

这是解释：

Limit  (cost=1.28..177.77 rows=100 width=49) (actual time=6171.121..6171.850 rows=100 loops=1)
  ->  Nested Loop Anti Join …