Rename the Repository table to PoolRepository

To separate the different kinds of repositories we have at GitLab this
table will be renamed to pool_repositories. A project can, for now at
least, be member of none, or one of these. The table will get additional
columns in a later merge request where more logic is implemented for the
model.

Further included is a small refactor of logic around hashing ids for the
disk_path, mainly to ensure a previous implementation is reusable.

The disk_path for the pool_repositories table no longer has a NOT NULL
constraint, but given the hashing of the ID requires the DB to assign
the record an ID, an after_create hook is used to update the value.

A related MR is:
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/23143, adding
tables for 'normal' repositories and wiki_repositories.

3 files changed, 29 insertions, 9 deletions

diff --git a/db/migrate/20181120082911_rename_repositories_pool_repositories.rb b/db/migrate/20181120082911_rename_repositories_pool_repositories.rb
new file mode 100644
index 00000000000..165771c4775
--- /dev/null
+++ b/db/migrate/20181120082911_rename_repositories_pool_repositories.rb
@@ -0,0 +1,11 @@
+class RenameRepositoriesPoolRepositories < ActiveRecord::Migration[5.0]
+  include Gitlab::Database::MigrationHelpers
+
+  # This change doesn't require downtime as the table is not in use, so we're
+  # free to change an empty table
+  DOWNTIME = false
+
+  def change
+    rename_table :repositories, :pool_repositories
+  end
+end
diff --git a/db/migrate/20181123135036_drop_not_null_constraint_pool_repository_disk_path.rb b/db/migrate/20181123135036_drop_not_null_constraint_pool_repository_disk_path.rb
new file mode 100644
index 00000000000..bcd969e91c5
--- /dev/null
+++ b/db/migrate/20181123135036_drop_not_null_constraint_pool_repository_disk_path.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+class DropNotNullConstraintPoolRepositoryDiskPath < ActiveRecord::Migration[5.0]
+  DOWNTIME = false
+
+  def change
+    change_column_null :pool_repositories, :disk_path, true
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index e0ca571df5a..810afcdcfd5 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -1501,6 +1501,13 @@ ActiveRecord::Schema.define(version: 20181126153547) do
     t.index ["user_id"], name: "index_personal_access_tokens_on_user_id", using: :btree
   end
 
+  create_table "pool_repositories", id: :bigserial, force: :cascade do |t|
+    t.integer "shard_id", null: false
+    t.string "disk_path"
+    t.index ["disk_path"], name: "index_pool_repositories_on_disk_path", unique: true, using: :btree
+    t.index ["shard_id"], name: "index_pool_repositories_on_shard_id", using: :btree
+  end
+
   create_table "programming_languages", force: :cascade do |t|
     t.string "name", null: false
     t.string "color", null: false
@@ -1798,13 +1805,6 @@ ActiveRecord::Schema.define(version: 20181126153547) do
     t.index ["project_id"], name: "index_remote_mirrors_on_project_id", using: :btree
   end
 
-  create_table "repositories", id: :bigserial, force: :cascade do |t|
-    t.integer "shard_id", null: false
-    t.string "disk_path", null: false
-    t.index ["disk_path"], name: "index_repositories_on_disk_path", unique: true, using: :btree
-    t.index ["shard_id"], name: "index_repositories_on_shard_id", using: :btree
-  end
-
   create_table "repository_languages", id: false, force: :cascade do |t|
     t.integer "project_id", null: false
     t.integer "programming_language_id", null: false
@@ -2377,6 +2377,7 @@ ActiveRecord::Schema.define(version: 20181126153547) do
   add_foreign_key "oauth_openid_requests", "oauth_access_grants", column: "access_grant_id", name: "fk_oauth_openid_requests_oauth_access_grants_access_grant_id"
   add_foreign_key "pages_domains", "projects", name: "fk_ea2f6dfc6f", on_delete: :cascade
   add_foreign_key "personal_access_tokens", "users"
+  add_foreign_key "pool_repositories", "shards", on_delete: :restrict
   add_foreign_key "project_authorizations", "projects", on_delete: :cascade
   add_foreign_key "project_authorizations", "users", on_delete: :cascade
   add_foreign_key "project_auto_devops", "projects", on_delete: :cascade
@@ -2389,7 +2390,7 @@ ActiveRecord::Schema.define(version: 20181126153547) do
   add_foreign_key "project_import_data", "projects", name: "fk_ffb9ee3a10", on_delete: :cascade
   add_foreign_key "project_mirror_data", "projects", on_delete: :cascade
   add_foreign_key "project_statistics", "projects", on_delete: :cascade
-  add_foreign_key "projects", "repositories", column: "pool_repository_id", name: "fk_6e5c14658a", on_delete: :nullify
+  add_foreign_key "projects", "pool_repositories", name: "fk_6e5c14658a", on_delete: :nullify
   add_foreign_key "prometheus_metrics", "projects", on_delete: :cascade
   add_foreign_key "protected_branch_merge_access_levels", "protected_branches", name: "fk_8a3072ccb3", on_delete: :cascade
   add_foreign_key "protected_branch_push_access_levels", "protected_branches", name: "fk_9ffc86a3d9", on_delete: :cascade
@@ -2401,7 +2402,6 @@ ActiveRecord::Schema.define(version: 20181126153547) do
   add_foreign_key "push_event_payloads", "events", name: "fk_36c74129da", on_delete: :cascade
   add_foreign_key "releases", "projects", name: "fk_47fe2a0596", on_delete: :cascade
   add_foreign_key "remote_mirrors", "projects", on_delete: :cascade
-  add_foreign_key "repositories", "shards", on_delete: :restrict
   add_foreign_key "repository_languages", "projects", on_delete: :cascade
   add_foreign_key "resource_label_events", "issues", on_delete: :cascade
   add_foreign_key "resource_label_events", "labels", on_delete: :nullify