Refactor migration to not require downtime

1 files changed, 18 insertions, 9 deletions

diff --git a/db/migrate/20170124174637_add_foreign_keys_to_timelogs.rb b/db/migrate/20170124174637_add_foreign_keys_to_timelogs.rb
index 7956463e12c..69bfa2d3fc4 100644
--- a/db/migrate/20170124174637_add_foreign_keys_to_timelogs.rb
+++ b/db/migrate/20170124174637_add_foreign_keys_to_timelogs.rb
@@ -5,11 +5,11 @@ class AddForeignKeysToTimelogs < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 
   # Set this constant to true if this migration requires downtime.
-  DOWNTIME = true
+  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 = 'Adding foreign keys'
+  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
@@ -20,23 +20,32 @@ class AddForeignKeysToTimelogs < ActiveRecord::Migration
   #
   # To disable transactions uncomment the following line and remove these
   # comments:
-  # disable_ddl_transaction!
+  disable_ddl_transaction!
 
   def up
     change_table :timelogs do |t|
-      t.references :issue, index: true, foreign_key: { on_delete: :cascade }
-      t.references :merge_request, index: true, foreign_key: { on_delete: :cascade }
+      t.column :issue_id, :integer
+      t.column :merge_request_id, :integer
+    end
+
+    add_concurrent_index :timelogs, :issue_id
+    add_concurrent_index :timelogs, :merge_request_id
+
+    if Gitlab::Database.postgresql?
+      execute <<-EOF
+        ALTER TABLE timelogs ADD CONSTRAINT "fk_timelogs_issues_issue_id" FOREIGN KEY (issue_id) REFERENCES "issues" (id) ON DELETE CASCADE NOT VALID;
+        ALTER TABLE timelogs ADD CONSTRAINT "fk_timelogs_merge_requests_merge_request_id" FOREIGN KEY (merge_request_id) REFERENCES "merge_requests" (id) ON DELETE CASCADE NOT VALID;
+      EOF
+    else
+      execute "ALTER TABLE timelogs ADD CONSTRAINT fk_timelogs_issues_issue_id FOREIGN KEY (issue_id) REFERENCES issues(id) ON DELETE CASCADE;"
+      execute "ALTER TABLE timelogs ADD CONSTRAINT fk_timelogs_merge_requests_merge_request_id FOREIGN KEY (merge_request_id) REFERENCES merge_requests(id) ON DELETE CASCADE;"
     end
 
     Timelog.where(trackable_type: 'Issue').update_all("issue_id = trackable_id")
     Timelog.where(trackable_type: 'MergeRequest').update_all("merge_request_id = trackable_id")
-
-    remove_columns :timelogs, :trackable_id, :trackable_type
   end
 
   def down
-    add_reference :timelogs, :trackable, polymorphic: true, index: true
-
     Timelog.where('issue_id IS NOT NULL').update_all("trackable_id = issue_id, trackable_type = 'Issue'")
     Timelog.where('merge_request_id IS NOT NULL').update_all("trackable_id = merge_request_id, trackable_type = 'MergeRequest'")