Merge remote-tracking branch 'upstream/master' into 27377-preload-pipeline-entity27377-preload-pipeline-entity

* upstream/master: (2534 commits)
  Update VERSION to 9.3.0-pre
  Update CHANGELOG.md for 9.2.0
  removes unnecessary redundacy in usage ping doc
  Respect the typo as rubocop said
  Add a test to ensure this works on MySQL
  Change pipelines schedules help page path
  change domain to hostname in usage ping doc
  Fixes broken MySQL migration for retried
  Show password field mask while editing service settings
  Add notes for supported schedulers and cloud providers
  Move environment monitoring to environments doc
  Add docs for change of Cache/Artifact restore order"
  Avoid resource intensive login checks if password is not provided
  Change translation for 'coding' by 'desarrollo' for Spanish
  Add to docs: issues multiple assignees
  rename "Add emoji" and "Award emoji" to "Add reaction" where appropriate
  Add project and group notification settings info
  32570 Fix border-bottom for project activity tab
  Add users endpoint to frontend API class
  Rename users on mysql
  ...

1 files changed, 44 insertions, 0 deletions

diff --git a/db/migrate/20170320173259_migrate_assignees.rb b/db/migrate/20170320173259_migrate_assignees.rb
new file mode 100644
index 00000000000..23e7500a32d
--- /dev/null
+++ b/db/migrate/20170320173259_migrate_assignees.rb
@@ -0,0 +1,44 @@
+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class MigrateAssignees < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  # Set this constant to true if this migration requires downtime.
+  DOWNTIME = false
+
+  # When a migration requires downtime you **must** uncomment the following
+  # constant and define a short and easy to understand explanation as to why the
+  # migration requires downtime.
+  # DOWNTIME_REASON = ''
+
+  # When using the methods "add_concurrent_index" or "add_column_with_default"
+  # you must disable the use of transactions as these methods can not run in an
+  # existing transaction. When using "add_concurrent_index" make sure that this
+  # method is the _only_ method called in the migration, any other changes
+  # should go in a separate migration. This ensures that upon failure _only_ the
+  # index creation fails and can be retried or reverted easily.
+  #
+  # To disable transactions uncomment the following line and remove these
+  # comments:
+  disable_ddl_transaction!
+
+  def up
+    # Optimisation: this accounts for most of the invalid assignee IDs on GitLab.com
+    update_column_in_batches(:issues, :assignee_id, nil) do |table, query|
+      query.where(table[:assignee_id].eq(0))
+    end
+
+    users = Arel::Table.new(:users)
+
+    update_column_in_batches(:issues, :assignee_id, nil) do |table, query|
+      query.where(table[:assignee_id].not_eq(nil)\
+        .and(
+          users.project("true").where(users[:id].eq(table[:assignee_id])).exists.not
+        ))
+    end
+  end
+
+  def down
+  end
+end