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PERF: avoid OR in complex query

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10x perf improvement on front page for sitepoint
This commit is contained in:
Sam 2014-09-10 16:33:21 +10:00
parent b9c8ae588a
commit a8dc6daa38
1 changed files with 10 additions and 2 deletions
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12
app/models/topic_tracking_state.rb
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@ -144,7 +144,7 @@ class TopicTrackingState
LEFT JOIN categories c ON c.id = topics.category_id
WHERE u.id IN (:user_ids) AND
topics.archetype <> 'private_message' AND
((#{unread}) OR (#{new})) AND
(**COND**) AND
(topics.visible OR u.admin OR u.moderator) AND
topics.deleted_at IS NULL AND
( category_id IS NULL OR NOT c.read_restricted OR category_id IN (
@ -163,11 +163,19 @@ SQL
if topic_id
sql << " AND topics.id = :topic_id"
end
sql << " ORDER BY topics.bumped_at DESC LIMIT 500"
sql << " ORDER BY topics.bumped_at DESC LIMIT 250"
sql = wrap(sql.sub("**COND**", new), "A") << " UNION ALL " << wrap(sql.sub("**COND**", unread),"B")
SqlBuilder.new(sql)
.map_exec(TopicTrackingState, user_ids: user_ids, topic_id: topic_id)
end
private
def self.wrap(query, name)
"SELECT * FROM (#{query}) #{name}"
end
end