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Improve DB performance on getPostsAround() (#11662)

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This change modifies the database query used by the getPostsAround()
method in order to improve the performance of loading posts when
scrolling through a channel.
This commit is contained in:
Gabe Jackson
2019-07-18 12:16:45 -04:00
committed by Harrison Healey
parent 5f61047d02
commit 20f03f7656
1 changed files with 35 additions and 34 deletions
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69
store/sqlstore/post_store.go
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@@ -580,8 +580,7 @@ func (s *SqlPostStore) GetPostsAfter(channelId string, postId string, limit int,
}
func (s *SqlPostStore) getPostsAround(channelId string, postId string, limit int, offset int, before bool) (*model.PostList, *model.AppError) {
var direction string
var sort string
var direction, sort string
if before {
direction = "<"
sort = "DESC"
@@ -590,8 +589,7 @@ func (s *SqlPostStore) getPostsAround(channelId string, postId string, limit int
sort = "ASC"
}
var posts []*model.Post
var parents []*model.Post
var posts, parents []*model.Post
_, err := s.GetReplica().Select(&posts,
`SELECT
*
@@ -608,38 +606,40 @@ func (s *SqlPostStore) getPostsAround(channelId string, postId string, limit int
if err != nil {
return nil, model.NewAppError("SqlPostStore.GetPostContext", "store.sql_post.get_posts_around.get.app_error", nil, "channelId="+channelId+err.Error(), http.StatusInternalServerError)
}
_, err = s.GetReplica().Select(&parents,
`SELECT
q2.*
FROM
Posts q2
INNER JOIN
(SELECT DISTINCT
q3.Id, q3.RootId
FROM
(SELECT
Id, RootId
FROM
Posts
WHERE
CreateAt `+direction+` (SELECT CreateAt FROM Posts WHERE Id = :PostId)
AND ChannelId = :ChannelId
AND DeleteAt = 0
ORDER BY CreateAt `+sort+`
LIMIT :Limit OFFSET :Offset) q3 -- q3 contains the Id and RootId of every post in posts
) q1 -- q1 is q3 with the duplicates removed
ON q1.RootId = q2.Id -- This is the root post of a thread that appears in posts
OR q1.Id = q2.RootId -- This is a comment on a post in posts
OR (q2.RootId != '' AND q1.RootId = q2.RootId) -- This is a comment on a thread that appears in posts
WHERE
ChannelId = :ChannelId
AND DeleteAt = 0
ORDER BY CreateAt DESC`,
map[string]interface{}{"ChannelId": channelId, "PostId": postId, "Limit": limit, "Offset": offset})
if err != nil {
return nil, model.NewAppError("SqlPostStore.GetPostContext", "store.sql_post.get_posts_around.get_parent.app_error", nil, "channelId="+channelId+err.Error(), http.StatusInternalServerError)
if len(posts) > 0 {
rootIds := []string{}
for _, post := range posts {
rootIds = append(rootIds, post.Id)
if post.RootId != "" {
rootIds = append(rootIds, post.RootId)
}
}
keys, params := MapStringsToQueryParams(rootIds, "PostId")
params["ChannelId"] = channelId
params["PostId"] = postId
params["Limit"] = limit
params["Offset"] = offset
_, err = s.GetReplica().Select(&parents,
`SELECT
*
FROM
Posts
WHERE
(Id IN `+keys+` OR RootId IN `+keys+`)
AND ChannelId = :ChannelId
AND DeleteAt = 0
ORDER BY CreateAt DESC`,
params)
if err != nil {
return nil, model.NewAppError("SqlPostStore.GetPostContext", "store.sql_post.get_posts_around.get_parent.app_error", nil, "channelId="+channelId+err.Error(), http.StatusInternalServerError)
}
}
list := model.NewPostList()
// We need to flip the order if we selected backwards
@@ -659,6 +659,7 @@ func (s *SqlPostStore) getPostsAround(channelId string, postId string, limit int
for _, p := range parents {
list.AddPost(p)
}
return list, nil
}