Maintain index options during change_column operations

CHANGELOG.md

@@ -17,5 +17,6 @@
 - [#1320](https://github.com/rails-sqlserver/activerecord-sqlserver-adapter/pull/1320) Fix SQL statement to calculate `updated_at` when upserting.
 - [#1327](https://github.com/rails-sqlserver/activerecord-sqlserver-adapter/pull/1327) Fix multiple `nil` identity columns for merge insert.
 - [#1338](https://github.com/rails-sqlserver/activerecord-sqlserver-adapter/pull/1338) Fix `insert_all`/`upsert_all` for table names containing numbers.
+- [#1345](https://github.com/rails-sqlserver/activerecord-sqlserver-adapter/pull/1345) Maintain index options during `change_column` operations.
 
 Please check [8-0-stable](https://github.com/rails-sqlserver/activerecord-sqlserver-adapter/blob/8-0-stable/CHANGELOG.md) for previous changes.

lib/active_record/connection_adapters/sqlserver/schema_statements.rb

@@ -210,12 +210,14 @@ def change_column(table_name, column_name, type, options = {})
             sql_commands << "ALTER TABLE #{quote_table_name(table_name)} ADD CONSTRAINT #{default_constraint_name(table_name, column_name)} DEFAULT #{default} FOR #{quote_column_name(column_name)}"
           end
 
+          sql_commands.each { |c| execute(c) }
+
           # Add any removed indexes back
           indexes.each do |index|
-            sql_commands << "CREATE INDEX #{quote_table_name(index.name)} ON #{quote_table_name(table_name)} (#{index.columns.map { |c| quote_column_name(c) }.join(", ")})"
+            create_index_def = CreateIndexDefinition.new(index)
+            execute schema_creation.accept(create_index_def)
           end
 
-          sql_commands.each { |c| execute(c) }
           clear_cache!
         end
 

test/cases/change_column_index_test_sqlserver.rb

@@ -0,0 +1,108 @@
+# frozen_string_literal: true
+
+require "cases/helper_sqlserver"
+
+class ChangeColumnIndexTestSqlServer < ActiveRecord::TestCase
+  class CreateClientsWithUniqueIndex < ActiveRecord::Migration[8.0]
+    def up
+      create_table :clients do |t|
+        t.string :name, limit: 15
+      end
+      add_index :clients, :name, unique: true
+    end
+
+    def down
+      drop_table :clients
+    end
+  end
+
+  class CreateBlogPostsWithMultipleIndexesOnTheSameColumn < ActiveRecord::Migration[8.0]
+    def up
+      create_table :blog_posts do |t|
+        t.string :title, limit: 15
+        t.string :subtitle
+      end
+      add_index :blog_posts, :title, unique: true, where: "([blog_posts].[title] IS NOT NULL)", name: "custom_index_name"
+      add_index :blog_posts, [:title, :subtitle], unique: true
+    end
+
+    def down
+      drop_table :blog_posts
+    end
+  end
+
+  class ChangeClientsNameLength < ActiveRecord::Migration[8.0]
+    def up
+      change_column :clients, :name, :string, limit: 30
+    end
+  end
+
+  class ChangeBlogPostsTitleLength < ActiveRecord::Migration[8.0]
+    def up
+      change_column :blog_posts, :title, :string, limit: 30
+    end
+  end
+
+  before do
+    @old_verbose = ActiveRecord::Migration.verbose
+    ActiveRecord::Migration.verbose = false
+
+    CreateClientsWithUniqueIndex.new.up
+    CreateBlogPostsWithMultipleIndexesOnTheSameColumn.new.up
+  end
+
+  after do
+    CreateClientsWithUniqueIndex.new.down
+    CreateBlogPostsWithMultipleIndexesOnTheSameColumn.new.down
+
+    ActiveRecord::Migration.verbose = @old_verbose
+  end
+
+  def test_index_uniqueness_is_maintained_after_column_change
+    indexes = ActiveRecord::Base.connection.indexes("clients")
+    columns = ActiveRecord::Base.connection.columns("clients")
+    assert_equal columns.find { |column| column.name == "name" }.limit, 15
+    assert_equal indexes.size, 1
+    assert_equal indexes.first.name, "index_clients_on_name"
+    assert indexes.first.unique
+
+    ChangeClientsNameLength.new.up
+
+    indexes = ActiveRecord::Base.connection.indexes("clients")
+    columns = ActiveRecord::Base.connection.columns("clients")
+    assert_equal columns.find { |column| column.name == "name" }.limit, 30
+    assert_equal indexes.size, 1
+    assert_equal indexes.first.name, "index_clients_on_name"
+    assert indexes.first.unique
+  end
+
+  def test_multiple_index_options_are_maintained_after_column_change
+    indexes = ActiveRecord::Base.connection.indexes("blog_posts")
+    columns = ActiveRecord::Base.connection.columns("blog_posts")
+    assert_equal columns.find { |column| column.name == "title" }.limit, 15
+    assert_equal indexes.size, 2
+
+    index_1 = indexes.find { |index| index.columns == ["title"] }
+    assert_equal index_1.name, "custom_index_name"
+    assert_equal index_1.where, "([blog_posts].[title] IS NOT NULL)"
+    assert index_1.unique
+
+    index_2 = indexes.find { |index| index.columns == ["title", "subtitle"] }
+    assert index_2.unique
+
+    ChangeBlogPostsTitleLength.new.up
+
+    indexes = ActiveRecord::Base.connection.indexes("blog_posts")
+    columns = ActiveRecord::Base.connection.columns("blog_posts")
+    assert_equal columns.find { |column| column.name == "title" }.limit, 30
+    assert_equal indexes.size, 2
+
+    index_1 = indexes.find { |index| index.columns == ["title"] }
+    assert_equal index_1.name, "custom_index_name"
+    assert_equal index_1.where, "([blog_posts].[title] IS NOT NULL)"
+    assert index_1.unique
+
+    index_2 = indexes.find { |index| index.columns == ["title", "subtitle"] }
+    assert index_2.unique
+  end
+end