gitlab-org--gitlab-foss/db/post_migrate/20171124100152_remove_index...

class RemoveIndexOnMergeRequestDiffsMergeRequestDiffId < ActiveRecord::Migration[4.2]
  include Gitlab::Database::MigrationHelpers

  DOWNTIME = false

  disable_ddl_transaction!

  def up
    if index_exists?(:merge_request_diffs, :merge_request_id)
      remove_concurrent_index(:merge_request_diffs, :merge_request_id)
    end
  end

  def down
    add_concurrent_index(:merge_request_diffs, :merge_request_id)
  end
end
Add version 4.2 to all existing migrations DB schema generated by a migration may look different in rails 4 and 5 (because rails 5 may use different default values). For this reason it's important to explicitly set for which rails version a migration was written for. See https://stackoverflow.com/questions/35929869/activerecordmigration-deprecation-warning-asks-for-rails-version-but-im-no/35930912#35930912 2018-11-13 07:27:31 +00:00			`class RemoveIndexOnMergeRequestDiffsMergeRequestDiffId < ActiveRecord::Migration[4.2]`
Improve indexes on merge_request_diffs For getting the SHAs from an MR to find pipelines, we get the last 100 MR diffs for the MR, and find commits from those. This was un-indexed before, because the index was not a composite index on merge_request_diff_id, id. Changing that means that this scope can exclusively use indexes. 2017-11-24 10:11:37 +00:00			`include Gitlab::Database::MigrationHelpers`

			`DOWNTIME = false`

			`disable_ddl_transaction!`

			`def up`
			`if index_exists?(:merge_request_diffs, :merge_request_id)`
			`remove_concurrent_index(:merge_request_diffs, :merge_request_id)`
			`end`
			`end`

			`def down`
			`add_concurrent_index(:merge_request_diffs, :merge_request_id)`
			`end`
			`end`