kotovalexarian-likes-gitlab/gitlab-org--gitlab-foss
1
0
Fork 0
Code Releases Activity

Added partial index for merge requests

Browse source 
This index is added on `(target_project_id, iid)` and has a `WHERE state
= 'opened'` condition. Using this index we can drastically improve the
performance of the query used to count the total number of merge
requests in a group. Without this index the query would eventually
perform the following:

    ->  Index Scan using index_merge_requests_on_target_project_id_and_iid on merge_requests  (cost=0.43..4.89 rows=7 width=4) (actual time=0.058..0.353 rows=6 loops=228)
          Index Cond: (target_project_id = projects.id)
          Filter: ((state)::text = 'opened'::text)
          Rows Removed by Filter: 141
          Buffers: shared hit=34351 dirtied=1

Out of the ~180 milliseconds the entire query would take, around 170
milliseconds was spent in just this segment. With the index in place,
the above segment is turned into the following:

    ->  Index Only Scan using yorick_test on merge_requests  (cost=0.42..0.55 rows=7 width=4) (actual time=0.004..0.010 rows=6 loops=228)
          Index Cond: (target_project_id = projects.id)
          Heap Fetches: 419
          Buffers: shared hit=1381

The index also reduces the total query time to roughly 10 milliseconds.
This commit is contained in:
Yorick Peterse 2018-05-24 15:34:14 +02:00
parent 77d4546eda
commit 709dd23760
No known key found for this signature in database
GPG key ID: EDD30D2BEB691AC9
2 changed files with 29 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

27
db/migrate/20180524132016_merge_requests_target_id_iid_state_partial_index.rb Normal file
View file

@ -0,0 +1,27 @@
# See http://doc.gitlab.com/ce/development/migration_style_guide.html
# for more information on how to write migrations for GitLab.
class MergeRequestsTargetIdIidStatePartialIndex < ActiveRecord::Migration
include Gitlab::Database::MigrationHelpers
# Set this constant to true if this migration requires downtime.
DOWNTIME = false
INDEX_NAME = 'index_merge_requests_on_target_project_id_and_iid_opened'
disable_ddl_transaction!
def up
# On GitLab.com this index will take up roughly 5 MB of space.
add_concurrent_index(
:merge_requests,
[:target_project_id, :iid],
where: "state = 'opened'",
name: INDEX_NAME
)
end
def down
remove_concurrent_index_by_name(:merge_requests, INDEX_NAME)
end
end

3
db/schema.rb
View file

@ -11,7 +11,7 @@
#
# It's strongly recommended that you check this file into your version control system.
ActiveRecord::Schema.define(version: 20180521171529) do
ActiveRecord::Schema.define(version: 20180524132016) do
# These are extensions that must be enabled in order to support this database
enable_extension "plpgsql"
@ -1232,6 +1232,7 @@ ActiveRecord::Schema.define(version: 20180521171529) do
add_index "merge_requests", ["source_project_id", "source_branch"], name: "index_merge_requests_on_source_project_id_and_source_branch", using: :btree
add_index "merge_requests", ["target_branch"], name: "index_merge_requests_on_target_branch", using: :btree
add_index "merge_requests", ["target_project_id", "iid"], name: "index_merge_requests_on_target_project_id_and_iid", unique: true, using: :btree
add_index "merge_requests", ["target_project_id", "iid"], name: "index_merge_requests_on_target_project_id_and_iid_opened", where: "((state)::text = 'opened'::text)", using: :btree
add_index "merge_requests", ["target_project_id", "merge_commit_sha", "id"], name: "index_merge_requests_on_tp_id_and_merge_commit_sha_and_id", using: :btree
add_index "merge_requests", ["title"], name: "index_merge_requests_on_title", using: :btree
add_index "merge_requests", ["title"], name: "index_merge_requests_on_title_trigram", using: :gin, opclasses: {"title"=>"gin_trgm_ops"}