1 files changed, 25 insertions, 0 deletions
diff --git a/db/migrate/20201110221400_create_experiment_subjects.rb b/db/migrate/20201110221400_create_experiment_subjects.rb
new file mode 100644
index 00000000000..0c04d5b219f
--- /dev/null
+++ b/db/migrate/20201110221400_create_experiment_subjects.rb
@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+class CreateExperimentSubjects < ActiveRecord::Migration[6.0]
+  DOWNTIME = false
+
+  def up
+    create_table :experiment_subjects do |t|
+      t.references :experiment, index: true, foreign_key: { on_delete: :cascade }, null: false
+      t.bigint :user_id, index: true
+      t.bigint :group_id, index: true
+      t.bigint :project_id, index: true
+      t.integer :variant, limit: 2, null: false, default: 0
+      t.timestamps_with_timezone null: false
+    end
+
+    # Require exactly one of user_id, group_id, or project_id to be NOT NULL
+    execute <<-SQL
+      ALTER TABLE experiment_subjects ADD CONSTRAINT chk_has_one_subject CHECK (num_nonnulls(user_id, group_id, project_id) = 1);
+    SQL
+  end
+
+  def down
+    drop_table :experiment_subjects
+  end
+end