[ci skip] Merge branch 'master' into 36400-trigger-job36400-trigger-job

* master: (21 commits)
  Changing OAuth lookup to be case insensitive
  Delete orphaned fork networks in a migration
  Delete the fork network when removing the last membership
  Resolve "Performance issues when loading large number of wiki pages"
  Exports a couple of project related code as es6 modules
  Fix go-import meta data when enabled_git_access_protocol is a blank string
  Add dropdowns documentation
  Convert migration to populate latest merge request ID into a background migration
  Set 0.69.0 instead of latest for codeclimate image
  Fix hashed storage with project transfers to another namespace
  De-duplicate background migration matchers defined in spec/support/migrations_helpers.rb
  Update database_debugging.md
  Update database_debugging.md
  Move installation of apps higher
  Change to Google Kubernetes Cluster and add internal links
  Add Ingress description from official docs
  Add info on creating your own k8s cluster from the cluster page
  Add info about the installed apps in the Cluster docs
  Update HA README.md to clarify GitLab support does not troubleshoot DRBD.
  Optimise getting the pipeline status of commits
  ...

1 files changed, 36 insertions, 0 deletions

diff --git a/db/post_migrate/20171114104051_remove_empty_fork_networks.rb b/db/post_migrate/20171114104051_remove_empty_fork_networks.rb
new file mode 100644
index 00000000000..2fe99a1b9c1
--- /dev/null
+++ b/db/post_migrate/20171114104051_remove_empty_fork_networks.rb
@@ -0,0 +1,36 @@
+class RemoveEmptyForkNetworks < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+  BATCH_SIZE = 10_000
+
+  class MigrationForkNetwork < ActiveRecord::Base
+    include EachBatch
+
+    self.table_name = 'fork_networks'
+  end
+
+  class MigrationForkNetworkMembers < ActiveRecord::Base
+    self.table_name = 'fork_network_members'
+  end
+
+  disable_ddl_transaction!
+
+  def up
+    say 'Deleting empty ForkNetworks in batches'
+
+    has_members = MigrationForkNetworkMembers
+                    .where('fork_network_members.fork_network_id = fork_networks.id')
+                    .select(1)
+    MigrationForkNetwork.where('NOT EXISTS (?)', has_members)
+      .each_batch(of: BATCH_SIZE) do |networks|
+      deleted = networks.delete_all
+
+      say "Deleted #{deleted} rows in batch"
+    end
+  end
+
+  def down
+    # nothing
+  end
+end