Commit 5cecff89 authored by Stan Hu's avatar Stan Hu Committed by Sean McGivern

Convert migration to populate latest merge request ID into a background migration

This is to smear updates over a few hours to avoid causing excessive
replication lag as seen in https://gitlab.com/gitlab-com/infrastructure/issues/3235.
parent d41e66cb
class PopulateMergeRequestsLatestMergeRequestDiffId < ActiveRecord::Migration
include Gitlab::Database::MigrationHelpers
DOWNTIME = false
BATCH_SIZE = 1_000
class MergeRequest < ActiveRecord::Base
self.table_name = 'merge_requests'
include ::EachBatch
end
disable_ddl_transaction!
def up
update = '
latest_merge_request_diff_id = (
SELECT MAX(id)
FROM merge_request_diffs
WHERE merge_requests.id = merge_request_diffs.merge_request_id
)'.squish
MergeRequest.where(latest_merge_request_diff_id: nil).each_batch(of: BATCH_SIZE) do |relation|
relation.update_all(update)
end
end
end
class ScheduleMergeRequestLatestMergeRequestDiffIdMigrations < ActiveRecord::Migration
include Gitlab::Database::MigrationHelpers
DOWNTIME = false
BATCH_SIZE = 50_000
MIGRATION = 'PopulateMergeRequestsLatestMergeRequestDiffId'
disable_ddl_transaction!
class MergeRequest < ActiveRecord::Base
self.table_name = 'merge_requests'
include ::EachBatch
end
# On GitLab.com, we saw that we generated about 500,000 dead tuples over 5 minutes.
# To keep replication lag from ballooning, we'll aim for 50,000 updates over 5 minutes.
#
# Assuming that there are 5 million rows affected (which is more than on
# GitLab.com), and that each batch of 50,000 rows takes up to 5 minutes, then
# we can migrate all the rows in 8.5 hours.
def up
MergeRequest.where(latest_merge_request_diff_id: nil).each_batch(of: BATCH_SIZE) do |relation, index|
range = relation.pluck('MIN(id)', 'MAX(id)').first
BackgroundMigrationWorker.perform_in(index * 5.minutes, MIGRATION, range)
end
end
end
module Gitlab
module BackgroundMigration
class PopulateMergeRequestsLatestMergeRequestDiffId
BATCH_SIZE = 1_000
class MergeRequest < ActiveRecord::Base
self.table_name = 'merge_requests'
include ::EachBatch
end
def perform(start_id, stop_id)
update = '
latest_merge_request_diff_id = (
SELECT MAX(id)
FROM merge_request_diffs
WHERE merge_requests.id = merge_request_diffs.merge_request_id
)'.squish
MergeRequest
.where(id: start_id..stop_id)
.where(latest_merge_request_diff_id: nil)
.each_batch(of: BATCH_SIZE) do |relation|
relation.update_all(update)
end
end
end
end
end
require 'spec_helper'
require Rails.root.join('db', 'post_migrate', '20171026082505_populate_merge_requests_latest_merge_request_diff_id')
describe PopulateMergeRequestsLatestMergeRequestDiffId, :migration do
describe Gitlab::BackgroundMigration::PopulateMergeRequestsLatestMergeRequestDiffId, :migration, schema: 20171026082505 do
let(:projects_table) { table(:projects) }
let(:merge_requests_table) { table(:merge_requests) }
let(:merge_request_diffs_table) { table(:merge_request_diffs) }
......@@ -27,30 +26,32 @@ describe PopulateMergeRequestsLatestMergeRequestDiffId, :migration do
merge_request_diffs_table.where(merge_request_id: merge_request.id)
end
describe '#up' do
describe '#perform' do
it 'ignores MRs without diffs' do
merge_request_without_diff = create_mr!('without_diff')
mr_id = merge_request_without_diff.id
expect(merge_request_without_diff.latest_merge_request_diff_id).to be_nil
expect { migrate! }
expect { subject.perform(mr_id, mr_id) }
.not_to change { merge_request_without_diff.reload.latest_merge_request_diff_id }
end
it 'ignores MRs that have a diff ID already set' do
merge_request_with_multiple_diffs = create_mr!('with_multiple_diffs', diffs: 3)
diff_id = diffs_for(merge_request_with_multiple_diffs).minimum(:id)
mr_id = merge_request_with_multiple_diffs.id
merge_request_with_multiple_diffs.update!(latest_merge_request_diff_id: diff_id)
expect { migrate! }
expect { subject.perform(mr_id, mr_id) }
.not_to change { merge_request_with_multiple_diffs.reload.latest_merge_request_diff_id }
end
it 'migrates multiple MR diffs to the correct values' do
merge_requests = Array.new(3).map.with_index { |_, i| create_mr!(i, diffs: 3) }
migrate!
subject.perform(merge_requests.first.id, merge_requests.last.id)
merge_requests.each do |merge_request|
expect(merge_request.reload.latest_merge_request_diff_id)
......
require 'spec_helper'
require Rails.root.join('db', 'post_migrate', '20171026082505_schedule_merge_request_latest_merge_request_diff_id_migrations')
describe ScheduleMergeRequestLatestMergeRequestDiffIdMigrations, :migration, :sidekiq do
let(:projects_table) { table(:projects) }
let(:merge_requests_table) { table(:merge_requests) }
let(:merge_request_diffs_table) { table(:merge_request_diffs) }
let(:project) { projects_table.create!(name: 'gitlab', path: 'gitlab-org/gitlab-ce') }
let!(:merge_request_1) { create_mr!('mr_1', diffs: 1) }
let!(:merge_request_2) { create_mr!('mr_2', diffs: 2) }
let!(:merge_request_migrated) { create_mr!('merge_request_migrated', diffs: 3) }
let!(:merge_request_4) { create_mr!('mr_4', diffs: 3) }
def create_mr!(name, diffs: 0)
merge_request =
merge_requests_table.create!(target_project_id: project.id,
target_branch: 'master',
source_project_id: project.id,
source_branch: name,
title: name)
diffs.times do
merge_request_diffs_table.create!(merge_request_id: merge_request.id)
end
merge_request
end
def diffs_for(merge_request)
merge_request_diffs_table.where(merge_request_id: merge_request.id)
end
before do
stub_const("#{described_class.name}::BATCH_SIZE", 1)
diff_id = diffs_for(merge_request_migrated).minimum(:id)
merge_request_migrated.update!(latest_merge_request_diff_id: diff_id)
end
it 'correctly schedules background migrations' do
Sidekiq::Testing.fake! do
Timecop.freeze do
migrate!
expect(described_class::MIGRATION).to be_scheduled_migration(5.minutes, merge_request_1.id, merge_request_1.id)
expect(described_class::MIGRATION).to be_scheduled_migration(10.minutes, merge_request_2.id, merge_request_2.id)
expect(described_class::MIGRATION).to be_scheduled_migration(15.minutes, merge_request_4.id, merge_request_4.id)
expect(BackgroundMigrationWorker.jobs.size).to eq 3
end
end
end
it 'schedules background migrations' do
Sidekiq::Testing.inline! do
expect(merge_requests_table.where(latest_merge_request_diff_id: nil).count).to eq 3
migrate!
expect(merge_requests_table.where(latest_merge_request_diff_id: nil).count).to eq 0
end
end
end
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