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authorYorick Peterse <yorickpeterse@gmail.com>2015-11-11 17:14:47 +0100
committerYorick Peterse <yorickpeterse@gmail.com>2015-11-18 13:02:43 +0100
commit054f2f98eda60682fd796a1f66681accc6f7ce1c (patch)
tree25af03f9550b26205f8553e440466cda9b72d3c6
parent21a59b23fe4d8bc4331f746c75f9242a49d75faa (diff)
downloadgitlab-ce-054f2f98eda60682fd796a1f66681accc6f7ce1c.tar.gz
Faster way of obtaining latest event update time
Instead of using MAX(events.updated_at) we can simply sort the events in descending order by the "id" column and grab the first row. In other words, instead of this: SELECT max(events.updated_at) AS max_id FROM events LEFT OUTER JOIN projects ON projects.id = events.project_id LEFT OUTER JOIN namespaces ON namespaces.id = projects.namespace_id WHERE events.author_id IS NOT NULL AND events.project_id IN (13083); we can use this: SELECT events.updated_at AS max_id FROM events LEFT OUTER JOIN projects ON projects.id = events.project_id LEFT OUTER JOIN namespaces ON namespaces.id = projects.namespace_id WHERE events.author_id IS NOT NULL AND events.project_id IN (13083) ORDER BY events.id DESC LIMIT 1; This has the benefit that on PostgreSQL a backwards index scan can be used, which due to the "LIMIT 1" will at most process only a single row. This in turn greatly speeds up the process of grabbing the latest update time. This can be confirmed by looking at the query plans. The first query produces the following plan: Aggregate (cost=43779.84..43779.85 rows=1 width=12) (actual time=2142.462..2142.462 rows=1 loops=1) -> Index Scan using index_events_on_project_id on events (cost=0.43..43704.69 rows=30060 width=12) (actual time=0.033..2138.086 rows=32769 loops=1) Index Cond: (project_id = 13083) Filter: (author_id IS NOT NULL) Planning time: 1.248 ms Execution time: 2142.548 ms The second query in turn produces the following plan: Limit (cost=0.43..41.65 rows=1 width=16) (actual time=1.394..1.394 rows=1 loops=1) -> Index Scan Backward using events_pkey on events (cost=0.43..1238907.96 rows=30060 width=16) (actual time=1.394..1.394 rows=1 loops=1) Filter: ((author_id IS NOT NULL) AND (project_id = 13083)) Rows Removed by Filter: 2104 Planning time: 0.166 ms Execution time: 1.408 ms According to the above plans the 2nd query is around 1500 times faster. However, re-running the first query produces timings of around 80 ms, making the 2nd query "only" around 55 times faster.
-rw-r--r--app/models/event.rb6
-rw-r--r--app/views/dashboard/projects/index.atom.builder2
-rw-r--r--app/views/groups/show.atom.builder2
-rw-r--r--app/views/projects/show.atom.builder2
-rw-r--r--app/views/users/show.atom.builder2
-rw-r--r--spec/models/event_spec.rb21
6 files changed, 31 insertions, 4 deletions
diff --git a/app/models/event.rb b/app/models/event.rb
index bf64ac29d32..7618b503d84 100644
--- a/app/models/event.rb
+++ b/app/models/event.rb
@@ -63,6 +63,12 @@ class Event < ActiveRecord::Base
Event::PUSHED, ["MergeRequest", "Issue"],
[Event::CREATED, Event::CLOSED, Event::MERGED])
end
+
+ def latest_update_time
+ row = select(:updated_at, :project_id).reorder(id: :desc).take
+
+ row ? row.updated_at : nil
+ end
end
def proper?
diff --git a/app/views/dashboard/projects/index.atom.builder b/app/views/dashboard/projects/index.atom.builder
index d2c51486841..c8c219f4cca 100644
--- a/app/views/dashboard/projects/index.atom.builder
+++ b/app/views/dashboard/projects/index.atom.builder
@@ -4,7 +4,7 @@ xml.feed "xmlns" => "http://www.w3.org/2005/Atom", "xmlns:media" => "http://sear
xml.link href: dashboard_projects_url(format: :atom, private_token: current_user.try(:private_token)), rel: "self", type: "application/atom+xml"
xml.link href: dashboard_projects_url, rel: "alternate", type: "text/html"
xml.id dashboard_projects_url
- xml.updated @events.maximum(:updated_at).strftime("%Y-%m-%dT%H:%M:%SZ") if @events.any?
+ xml.updated @events.latest_update_time.strftime("%Y-%m-%dT%H:%M:%SZ") if @events.any?
@events.each do |event|
event_to_atom(xml, event)
diff --git a/app/views/groups/show.atom.builder b/app/views/groups/show.atom.builder
index a91d1a6e94b..7ea574434c3 100644
--- a/app/views/groups/show.atom.builder
+++ b/app/views/groups/show.atom.builder
@@ -4,7 +4,7 @@ xml.feed "xmlns" => "http://www.w3.org/2005/Atom", "xmlns:media" => "http://sear
xml.link href: group_url(@group, format: :atom, private_token: current_user.try(:private_token)), rel: "self", type: "application/atom+xml"
xml.link href: group_url(@group), rel: "alternate", type: "text/html"
xml.id group_url(@group)
- xml.updated @events.maximum(:updated_at).strftime("%Y-%m-%dT%H:%M:%SZ") if @events.any?
+ xml.updated @events.latest_update_time.strftime("%Y-%m-%dT%H:%M:%SZ") if @events.any?
@events.each do |event|
event_to_atom(xml, event)
diff --git a/app/views/projects/show.atom.builder b/app/views/projects/show.atom.builder
index 242684e5c7c..15c49767556 100644
--- a/app/views/projects/show.atom.builder
+++ b/app/views/projects/show.atom.builder
@@ -4,7 +4,7 @@ xml.feed "xmlns" => "http://www.w3.org/2005/Atom", "xmlns:media" => "http://sear
xml.link href: namespace_project_url(@project.namespace, @project, format: :atom, private_token: current_user.try(:private_token)), rel: "self", type: "application/atom+xml"
xml.link href: namespace_project_url(@project.namespace, @project), rel: "alternate", type: "text/html"
xml.id namespace_project_url(@project.namespace, @project)
- xml.updated @events.maximum(:updated_at).strftime("%Y-%m-%dT%H:%M:%SZ") if @events.any?
+ xml.updated @events.latest_update_time.strftime("%Y-%m-%dT%H:%M:%SZ") if @events.any?
@events.each do |event|
event_to_atom(xml, event)
diff --git a/app/views/users/show.atom.builder b/app/views/users/show.atom.builder
index 50232dc7186..2fe5b7fac83 100644
--- a/app/views/users/show.atom.builder
+++ b/app/views/users/show.atom.builder
@@ -4,7 +4,7 @@ xml.feed "xmlns" => "http://www.w3.org/2005/Atom", "xmlns:media" => "http://sear
xml.link href: user_url(@user, :atom), rel: "self", type: "application/atom+xml"
xml.link href: user_url(@user), rel: "alternate", type: "text/html"
xml.id user_url(@user)
- xml.updated @events.maximum(:updated_at).strftime("%Y-%m-%dT%H:%M:%SZ") if @events.any?
+ xml.updated @events.latest_update_time.strftime("%Y-%m-%dT%H:%M:%SZ") if @events.any?
@events.each do |event|
event_to_atom(xml, event)
diff --git a/spec/models/event_spec.rb b/spec/models/event_spec.rb
index 0f32f162a10..f46c50ed6f3 100644
--- a/spec/models/event_spec.rb
+++ b/spec/models/event_spec.rb
@@ -64,4 +64,25 @@ describe Event do
it { expect(@event.branch_name).to eq("master") }
it { expect(@event.author).to eq(@user) }
end
+
+ describe '.latest_update_time' do
+ describe 'when events are present' do
+ let(:time) { Time.utc(2015, 1, 1) }
+
+ before do
+ create(:closed_issue_event, updated_at: time)
+ create(:closed_issue_event, updated_at: time + 5)
+ end
+
+ it 'returns the latest update time' do
+ expect(Event.latest_update_time).to eq(time + 5)
+ end
+ end
+
+ describe 'when no events exist' do
+ it 'returns nil' do
+ expect(Event.latest_update_time).to be_nil
+ end
+ end
+ end
end