Rename the primary key index when renaming a table in pg

Also checked to make sure this does not affect foreign key constraints.
(It doesn't).

Fixes #12856
Closes #14088

1 files changed, 34 insertions, 0 deletions

diff --git a/activerecord/test/cases/adapters/postgresql/rename_table_test.rb b/activerecord/test/cases/adapters/postgresql/rename_table_test.rb
new file mode 100644
index 0000000000..056a035622
--- /dev/null
+++ b/activerecord/test/cases/adapters/postgresql/rename_table_test.rb
@@ -0,0 +1,34 @@
+require "cases/helper"
+
+class PostgresqlRenameTableTest < ActiveRecord::TestCase
+  def setup
+    @connection = ActiveRecord::Base.connection
+    @connection.create_table :before_rename, force: true
+  end
+
+  def teardown
+    @connection.execute 'DROP TABLE IF EXISTS "before_rename"'
+    @connection.execute 'DROP TABLE IF EXISTS "after_rename"'
+  end
+
+  test "renaming a table also renames the primary key index" do
+    # sanity check
+    assert_equal 1, num_indices_named("before_rename_pkey")
+    assert_equal 0, num_indices_named("after_rename_pkey")
+
+    @connection.rename_table :before_rename, :after_rename
+
+    assert_equal 0, num_indices_named("before_rename_pkey")
+    assert_equal 1, num_indices_named("after_rename_pkey")
+  end
+
+  private
+
+  def num_indices_named(name)
+    @connection.execute(<<-SQL).values.length
+      SELECT 1 FROM "pg_index"
+        JOIN "pg_class" ON "pg_index"."indexrelid" = "pg_class"."oid"
+        WHERE "pg_class"."relname" = '#{name}'
+    SQL
+  end
+end