Atomic generation of internal ids for issues.

2 files changed, 44 insertions, 0 deletions

diff --git a/db/migrate/20180305095250_create_internal_ids_table.rb b/db/migrate/20180305095250_create_internal_ids_table.rb
new file mode 100644
index 00000000000..19c1904bb43
--- /dev/null
+++ b/db/migrate/20180305095250_create_internal_ids_table.rb
@@ -0,0 +1,35 @@
+class CreateInternalIdsTable < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    create_table :internal_ids do |t|
+      t.references :project
+      t.integer :usage, null: false
+      t.integer :last_value, null: false
+    end
+
+    unless index_exists?(:internal_ids, [:usage, :project_id])
+      add_index :internal_ids, [:usage, :project_id], unique: true
+    end
+
+    unless foreign_key_exists?(:internal_ids, :project_id)
+      add_concurrent_foreign_key :internal_ids, :projects, column: :project_id, on_delete: :cascade
+    end
+  end
+
+  def down
+    drop_table :internal_ids
+  end
+
+  private
+
+  def foreign_key_exists?(table, column)
+    foreign_keys(table).any? do |key|
+      key.options[:column] == column.to_s
+    end
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index ab4370e2754..3785bf14d5c 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -866,6 +866,14 @@ ActiveRecord::Schema.define(version: 20180309160427) do
 
   add_index "identities", ["user_id"], name: "index_identities_on_user_id", using: :btree
 
+  create_table "internal_ids", force: :cascade do |t|
+    t.integer "project_id"
+    t.integer "usage", null: false
+    t.integer "last_value", null: false
+  end
+
+  add_index "internal_ids", ["usage", "project_id"], name: "index_internal_ids_on_usage_and_project_id", unique: true, using: :btree
+
   create_table "issue_assignees", id: false, force: :cascade do |t|
     t.integer "user_id", null: false
     t.integer "issue_id", null: false
@@ -2058,6 +2066,7 @@ ActiveRecord::Schema.define(version: 20180309160427) do
   add_foreign_key "gpg_signatures", "gpg_keys", on_delete: :nullify
   add_foreign_key "gpg_signatures", "projects", on_delete: :cascade
   add_foreign_key "group_custom_attributes", "namespaces", column: "group_id", on_delete: :cascade
+  add_foreign_key "internal_ids", "projects", name: "fk_f7d46b66c6", on_delete: :cascade
   add_foreign_key "issue_assignees", "issues", name: "fk_b7d881734a", on_delete: :cascade
   add_foreign_key "issue_assignees", "users", name: "fk_5e0c8d9154", on_delete: :cascade
   add_foreign_key "issue_metrics", "issues", on_delete: :cascade