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PERF: Avoid `NOT IN (<subquery>>` which can get really slow. 

```
EXPLAIN ANALYZE SELECT  "topics".*
FROM "topics" LEFT JOIN topic_users tu ON topics.id = tu.topic_id AND
tu.user_id = 13455
WHERE ("topics"."deleted_at" IS NULL)
AND (topics.archetype = 'private_message')
AND (
  topics.id IN (
    SELECT topic_id
    FROM topic_allowed_users
    WHERE user_id = 13455
   )
)
AND (
  topics.id IN (
    SELECT ta.topic_id
    FROM topic_allowed_users ta
    WHERE ta.user_id IN (2,1995,8307,17621,22980,-10)
  )
  OR
  topics.id IN (
    SELECT tg.topic_id
    FROM topic_allowed_groups tg
    WHERE tg.group_id IN (-10)
  )
)
AND (topics.id NOT IN (68559,60069,42145))
AND "topics"."visible" = 't'
ORDER BY topics.bumped_at
DESC LIMIT 5;
```

Planning time: 1.196 ms
Execution time: 21.176 ms

```
EXPLAIN ANALYZE SELECT  "topics".*
FROM "topics"
LEFT JOIN topic_users tu ON topics.id = tu.topic_id AND tu.user_id =
13455
LEFT JOIN topic_allowed_users ta ON topics.id = ta.topic_id AND
ta.user_id = 13455
LEFT JOIN topic_allowed_users ta2 ON topics.id = ta2.topic_id AND
ta2.user_id IN (2,1995,8307,17621,22980,-10)
LEFT JOIN topic_allowed_groups tg ON topics.id = tg.topic_id AND
tg.group_id IN (-10)
WHERE ("topics"."deleted_at" IS NULL)
AND (topics.archetype = 'private_message')
AND (ta.topic_id IS NOT NULL)
AND (ta2.topic_id IS NOT NULL OR tg.topic_id IS NOT NULL)
AND (topics.id NOT IN (68559,60069,42145))
AND "topics"."visible" = 't'
ORDER BY topics.bumped_at DESC
LIMIT 5;
```

Planning time: 1.792 ms
Execution time: 2.546 ms
This commit is contained in:
Guo Xiang Tan 2017-09-13 22:22:33 +08:00
parent b537bf1ba4
commit 28148197d6
1 changed files with 30 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

50
lib/topic_query.rb
View File

@ -107,8 +107,13 @@ class TopicQuery
if topic.private_message?
group_ids = topic.topic_allowed_groups
.where('group_id IN (SELECT group_id FROM group_users WHERE user_id = :user_id)', user_id: @user.id)
.joins("
LEFT JOIN group_users gu
ON topic_allowed_groups.group_id = gu.group_id
AND user_id = #{@user.id.to_i}
")
.pluck(:group_id)
{
topic: topic,
my_group_ids: group_ids,
@ -743,21 +748,24 @@ class TopicQuery
end
def related_messages_user(params)
messages_for_user
.limit(params[:count])
.where('topics.id IN (
SELECT ta.topic_id
FROM topic_allowed_users ta
WHERE ta.user_id IN (:user_ids)
) OR
topics.id IN (
SELECT tg.topic_id
FROM topic_allowed_groups tg
WHERE tg.group_id IN (:group_ids)
)
', user_ids: (params[:target_user_ids] || []) + [-10],
group_ids: ((params[:target_group_ids] - params[:my_group_ids]) || []) + [-10])
user_ids = ((params[:target_user_ids] || []) << -10)
user_ids = ActiveRecord::Base.send(:sanitize_sql_array, user_ids.join(','))
group_ids = (((params[:target_group_ids] - params[:my_group_ids]) || []) << -10)
group_ids = ActiveRecord::Base.send(:sanitize_sql_array, group_ids.join(','))
result = messages_for_user
.limit(params[:count])
.joins("
LEFT JOIN topic_allowed_users ta2
ON topics.id = ta2.topic_id
AND ta2.user_id IN (#{user_ids})",
)
.joins("
LEFT JOIN topic_allowed_groups tg
ON topics.id = tg.topic_id
AND tg.group_id IN (#{group_ids})",
)
.where("ta2.topic_id IS NOT NULL OR tg.topic_id IS NOT NULL")
end
def related_messages_group(params)
@ -793,11 +801,13 @@ class TopicQuery
end
def messages_for_user
base_messages.where('topics.id IN (
SELECT topic_id
FROM topic_allowed_users
WHERE user_id = :user_id
)', user_id: @user.id)
base_messages
.joins("
LEFT JOIN topic_allowed_users ta
ON topics.id = ta.topic_id
AND ta.user_id = #{@user.id.to_i}
")
.where("ta.topic_id IS NOT NULL")
end
def base_messages