From 89c9a6f1c1a64a236db8ce16dfde9e86a2bca448 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9CWill?= <“gia19001@byui.edu”>
Date: Wed, 11 Feb 2026 13:27:07 -0700
Subject: [PATCH 1/7] issue #611 solution

---
 .tool-versions                                |   2 +-
 CHANGELOG.md                                  |   6 +
 .../migration_generator.ex                    |  23 +++-
 test/migration_generator_test.exs             | 121 ++++++++++++++++++
 4 files changed, 149 insertions(+), 3 deletions(-)

diff --git a/.tool-versions b/.tool-versions
index 0fa52d96..ac3977b1 100644
--- a/.tool-versions
+++ b/.tool-versions
@@ -1,3 +1,3 @@
 erlang 27.1.2
-elixir 1.18.4-otp-27
+elixir 1.18.1
 pipx 1.8.0
diff --git a/CHANGELOG.md b/CHANGELOG.md
index f5b1d166..583bb5c1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,12 @@ See [Conventional Commits](https://www.conventionalcommits.org) for commit guide
 
 <!-- changelog -->
 
+## [Unreleased]
+
+### Bug Fixes:
+
+* avoid dropping and re-adding foreign key when only reference index changes (#611)
+
 ## [v2.6.29](https://github.com/ash-project/ash_postgres/compare/v2.6.28...v2.6.29) (2026-02-03)
 
 
diff --git a/lib/migration_generator/migration_generator.ex b/lib/migration_generator/migration_generator.ex
index 14c3079e..ee8ecb3c 100644
--- a/lib/migration_generator/migration_generator.ex
+++ b/lib/migration_generator/migration_generator.ex
@@ -2153,7 +2153,8 @@ defmodule AshPostgres.MigrationGenerator do
           table: snapshot.table,
           schema: snapshot.schema,
           source: attribute.source,
-          multitenancy: snapshot.multitenancy
+          multitenancy: snapshot.multitenancy,
+          old_multitenancy: old_snapshot.multitenancy
         }
       end)
 
@@ -2662,7 +2663,8 @@ defmodule AshPostgres.MigrationGenerator do
             []
           end
 
-        if Map.get(old_attribute, :references) != Map.get(new_attribute, :references) do
+        if Map.get(old_attribute, :references) != Map.get(new_attribute, :references) and
+             references_differ_beyond_index?(old_attribute, new_attribute) do
           redo_deferrability =
             if has_reference?(old_snapshot.multitenancy, old_attribute) and
                  differently_deferrable?(new_attribute, old_attribute) do
@@ -2770,6 +2772,23 @@ defmodule AshPostgres.MigrationGenerator do
 
   defp differently_deferrable?(_, _), do: false
 
+  # When the only reference change is index? (add/remove index), we should not emit
+  # DropForeignKey + AlterAttribute; the separate AddReferenceIndex/RemoveReferenceIndex
+  # operations handle it. This avoids migrations that drop and re-add the same FK.
+  defp references_differ_beyond_index?(old_attr, new_attr) do
+    old_refs = Map.get(old_attr, :references)
+    new_refs = Map.get(new_attr, :references)
+
+    cond do
+      old_refs == new_refs -> false
+      is_nil(old_refs) or is_nil(new_refs) -> true
+      true ->
+        old_without_index = Map.delete(old_refs, :index?)
+        new_without_index = Map.delete(new_refs, :index?)
+        old_without_index != new_without_index
+    end
+  end
+
   # This exists to handle the fact that the remapping of the key name -> source caused attributes
   # to be considered unequal. We ignore things that only differ in that way using this function.
   defp attributes_unequal?(left, right, repo, _old_snapshot, _new_snapshot, ignore_names?) do
diff --git a/test/migration_generator_test.exs b/test/migration_generator_test.exs
index 4345f3e6..1d2dc1db 100644
--- a/test/migration_generator_test.exs
+++ b/test/migration_generator_test.exs
@@ -1775,6 +1775,127 @@ defmodule AshPostgres.MigrationGeneratorTest do
       assert File.read!(file) =~ ~S{create index(:posts, [:post_id])}
     end
 
+    test "changing only reference index? does not drop and re-add foreign key (issue #611)" do
+      # First generate: reference with index?: true
+      defresource PostRefIdx, "posts" do
+        attributes do
+          uuid_primary_key(:id)
+          attribute(:key_id, :uuid, allow_nil?: false, public?: true)
+          attribute(:foobar, :string, public?: true)
+        end
+
+        actions do
+          defaults([:create, :read, :update, :destroy])
+        end
+      end
+
+      defresource Post2RefIdx, "posts" do
+        attributes do
+          uuid_primary_key(:id)
+          attribute(:name, :string, public?: true)
+          attribute(:related_key_id, :uuid, public?: true)
+        end
+
+        relationships do
+          belongs_to(:post, PostRefIdx, public?: true)
+        end
+
+        actions do
+          defaults([:create, :read, :update, :destroy])
+        end
+
+        postgres do
+          references do
+            reference(:post, index?: true)
+          end
+        end
+      end
+
+      defmodule DomainRefIdx do
+        use Ash.Domain
+        resources do
+          resource(PostRefIdx)
+          resource(Post2RefIdx)
+        end
+      end
+
+      AshPostgres.MigrationGenerator.generate(DomainRefIdx,
+        snapshot_path: "test_snapshots_path",
+        migration_path: "test_migration_path",
+        quiet: true,
+        format: false,
+        auto_name: true
+      )
+
+      # Second generate: same reference but index?: false (only index change)
+      defresource PostRefNoIdx, "posts" do
+        attributes do
+          uuid_primary_key(:id)
+          attribute(:key_id, :uuid, allow_nil?: false, public?: true)
+          attribute(:foobar, :string, public?: true)
+        end
+
+        actions do
+          defaults([:create, :read, :update, :destroy])
+        end
+      end
+
+      defresource Post2RefNoIdx, "posts" do
+        attributes do
+          uuid_primary_key(:id)
+          attribute(:name, :string, public?: true)
+          attribute(:related_key_id, :uuid, public?: true)
+        end
+
+        relationships do
+          belongs_to(:post, PostRefNoIdx, public?: true)
+        end
+
+        actions do
+          defaults([:create, :read, :update, :destroy])
+        end
+
+        postgres do
+          references do
+            reference(:post, index?: false)
+          end
+        end
+      end
+
+      defmodule DomainRefNoIdx do
+        use Ash.Domain
+        resources do
+          resource(PostRefNoIdx)
+          resource(Post2RefNoIdx)
+        end
+      end
+
+      AshPostgres.MigrationGenerator.generate(DomainRefNoIdx,
+        snapshot_path: "test_snapshots_path",
+        migration_path: "test_migration_path",
+        quiet: true,
+        format: false,
+        auto_name: true
+      )
+
+      [_, file2] =
+        Path.wildcard("test_migration_path/**/*_migrate_resources*.exs")
+        |> Enum.reject(&String.contains?(&1, "extensions"))
+        |> Enum.sort()
+
+      content = File.read!(file2)
+
+      # Should only drop the index, not touch the foreign key
+      assert content =~ ~S{drop_if_exists index(:posts, [:post_id])},
+             "migration should drop the reference index when index? changes to false"
+
+      refute content =~ ~S{drop constraint(:posts, "posts_post_id_fkey")},
+             "migration should not drop the foreign key when only index? changed (issue #611)"
+
+      refute content =~ ~S{modify :post_id, references(},
+             "migration should not modify references when only index? changed (issue #611)"
+    end
+
     test "references with deferrable modifications generate changes with the correct schema" do
       defposts do
         attributes do

From 6635753aca6ce885257e7016b05c691b67127e15 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9CWill?= <“gia19001@byui.edu”>
Date: Wed, 11 Feb 2026 13:27:07 -0700
Subject: [PATCH 2/7] issue #611 solution

---
 .tool-versions                                |   2 +-
 .../migration_generator.ex                    |  23 +++-
 test/migration_generator_test.exs             | 121 ++++++++++++++++++
 3 files changed, 143 insertions(+), 3 deletions(-)

diff --git a/.tool-versions b/.tool-versions
index 0fa52d96..ac3977b1 100644
--- a/.tool-versions
+++ b/.tool-versions
@@ -1,3 +1,3 @@
 erlang 27.1.2
-elixir 1.18.4-otp-27
+elixir 1.18.1
 pipx 1.8.0
diff --git a/lib/migration_generator/migration_generator.ex b/lib/migration_generator/migration_generator.ex
index 14c3079e..ee8ecb3c 100644
--- a/lib/migration_generator/migration_generator.ex
+++ b/lib/migration_generator/migration_generator.ex
@@ -2153,7 +2153,8 @@ defmodule AshPostgres.MigrationGenerator do
           table: snapshot.table,
           schema: snapshot.schema,
           source: attribute.source,
-          multitenancy: snapshot.multitenancy
+          multitenancy: snapshot.multitenancy,
+          old_multitenancy: old_snapshot.multitenancy
         }
       end)
 
@@ -2662,7 +2663,8 @@ defmodule AshPostgres.MigrationGenerator do
             []
           end
 
-        if Map.get(old_attribute, :references) != Map.get(new_attribute, :references) do
+        if Map.get(old_attribute, :references) != Map.get(new_attribute, :references) and
+             references_differ_beyond_index?(old_attribute, new_attribute) do
           redo_deferrability =
             if has_reference?(old_snapshot.multitenancy, old_attribute) and
                  differently_deferrable?(new_attribute, old_attribute) do
@@ -2770,6 +2772,23 @@ defmodule AshPostgres.MigrationGenerator do
 
   defp differently_deferrable?(_, _), do: false
 
+  # When the only reference change is index? (add/remove index), we should not emit
+  # DropForeignKey + AlterAttribute; the separate AddReferenceIndex/RemoveReferenceIndex
+  # operations handle it. This avoids migrations that drop and re-add the same FK.
+  defp references_differ_beyond_index?(old_attr, new_attr) do
+    old_refs = Map.get(old_attr, :references)
+    new_refs = Map.get(new_attr, :references)
+
+    cond do
+      old_refs == new_refs -> false
+      is_nil(old_refs) or is_nil(new_refs) -> true
+      true ->
+        old_without_index = Map.delete(old_refs, :index?)
+        new_without_index = Map.delete(new_refs, :index?)
+        old_without_index != new_without_index
+    end
+  end
+
   # This exists to handle the fact that the remapping of the key name -> source caused attributes
   # to be considered unequal. We ignore things that only differ in that way using this function.
   defp attributes_unequal?(left, right, repo, _old_snapshot, _new_snapshot, ignore_names?) do
diff --git a/test/migration_generator_test.exs b/test/migration_generator_test.exs
index 4345f3e6..1d2dc1db 100644
--- a/test/migration_generator_test.exs
+++ b/test/migration_generator_test.exs
@@ -1775,6 +1775,127 @@ defmodule AshPostgres.MigrationGeneratorTest do
       assert File.read!(file) =~ ~S{create index(:posts, [:post_id])}
     end
 
+    test "changing only reference index? does not drop and re-add foreign key (issue #611)" do
+      # First generate: reference with index?: true
+      defresource PostRefIdx, "posts" do
+        attributes do
+          uuid_primary_key(:id)
+          attribute(:key_id, :uuid, allow_nil?: false, public?: true)
+          attribute(:foobar, :string, public?: true)
+        end
+
+        actions do
+          defaults([:create, :read, :update, :destroy])
+        end
+      end
+
+      defresource Post2RefIdx, "posts" do
+        attributes do
+          uuid_primary_key(:id)
+          attribute(:name, :string, public?: true)
+          attribute(:related_key_id, :uuid, public?: true)
+        end
+
+        relationships do
+          belongs_to(:post, PostRefIdx, public?: true)
+        end
+
+        actions do
+          defaults([:create, :read, :update, :destroy])
+        end
+
+        postgres do
+          references do
+            reference(:post, index?: true)
+          end
+        end
+      end
+
+      defmodule DomainRefIdx do
+        use Ash.Domain
+        resources do
+          resource(PostRefIdx)
+          resource(Post2RefIdx)
+        end
+      end
+
+      AshPostgres.MigrationGenerator.generate(DomainRefIdx,
+        snapshot_path: "test_snapshots_path",
+        migration_path: "test_migration_path",
+        quiet: true,
+        format: false,
+        auto_name: true
+      )
+
+      # Second generate: same reference but index?: false (only index change)
+      defresource PostRefNoIdx, "posts" do
+        attributes do
+          uuid_primary_key(:id)
+          attribute(:key_id, :uuid, allow_nil?: false, public?: true)
+          attribute(:foobar, :string, public?: true)
+        end
+
+        actions do
+          defaults([:create, :read, :update, :destroy])
+        end
+      end
+
+      defresource Post2RefNoIdx, "posts" do
+        attributes do
+          uuid_primary_key(:id)
+          attribute(:name, :string, public?: true)
+          attribute(:related_key_id, :uuid, public?: true)
+        end
+
+        relationships do
+          belongs_to(:post, PostRefNoIdx, public?: true)
+        end
+
+        actions do
+          defaults([:create, :read, :update, :destroy])
+        end
+
+        postgres do
+          references do
+            reference(:post, index?: false)
+          end
+        end
+      end
+
+      defmodule DomainRefNoIdx do
+        use Ash.Domain
+        resources do
+          resource(PostRefNoIdx)
+          resource(Post2RefNoIdx)
+        end
+      end
+
+      AshPostgres.MigrationGenerator.generate(DomainRefNoIdx,
+        snapshot_path: "test_snapshots_path",
+        migration_path: "test_migration_path",
+        quiet: true,
+        format: false,
+        auto_name: true
+      )
+
+      [_, file2] =
+        Path.wildcard("test_migration_path/**/*_migrate_resources*.exs")
+        |> Enum.reject(&String.contains?(&1, "extensions"))
+        |> Enum.sort()
+
+      content = File.read!(file2)
+
+      # Should only drop the index, not touch the foreign key
+      assert content =~ ~S{drop_if_exists index(:posts, [:post_id])},
+             "migration should drop the reference index when index? changes to false"
+
+      refute content =~ ~S{drop constraint(:posts, "posts_post_id_fkey")},
+             "migration should not drop the foreign key when only index? changed (issue #611)"
+
+      refute content =~ ~S{modify :post_id, references(},
+             "migration should not modify references when only index? changed (issue #611)"
+    end
+
     test "references with deferrable modifications generate changes with the correct schema" do
       defposts do
         attributes do

From 76e3ca145f050e7cda1ff6e3c66bd8b994a4493c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9CWill?= <“gia19001@byui.edu”>
Date: Wed, 18 Feb 2026 13:09:27 -0700
Subject: [PATCH 3/7] Revert CHANGELOG and .tool-versions per maintainer
 feedback

---
 .tool-versions |  2 +-
 CHANGELOG.md   | 29 +++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/.tool-versions b/.tool-versions
index ac3977b1..0fa52d96 100644
--- a/.tool-versions
+++ b/.tool-versions
@@ -1,3 +1,3 @@
 erlang 27.1.2
-elixir 1.18.1
+elixir 1.18.4-otp-27
 pipx 1.8.0
diff --git a/CHANGELOG.md b/CHANGELOG.md
index f5b1d166..66cea698 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,35 @@ See [Conventional Commits](https://www.conventionalcommits.org) for commit guide
 
 <!-- changelog -->
 
+## [v2.6.32](https://github.com/ash-project/ash_postgres/compare/v2.6.31...v2.6.32) (2026-02-11)
+
+
+
+
+### Bug Fixes:
+
+* produce correct error on `restrict` managed_relationship behavior (#690) by lincolnhuls
+
+### Improvements:
+
+* Split up usage rules into sub-rules (#691) by Mylan Connolly
+
+## [v2.6.31](https://github.com/ash-project/ash_postgres/compare/v2.6.30...v2.6.31) (2026-02-05)
+
+
+
+
+### Bug Fixes:
+
+* handle atomic no_rollback errors during creates by Zach Daniel
+
+* correct test expectation for `first` aggregate with `include_nil?` (#683) by sevenseacat
+
+## [v2.6.30](https://github.com/ash-project/ash_postgres/compare/v2.6.29...v2.6.30) (2026-02-04)
+
+
+* fix for atomic create support
+
 ## [v2.6.29](https://github.com/ash-project/ash_postgres/compare/v2.6.28...v2.6.29) (2026-02-03)
 
 

From c00ef1779eca023dbb5c0c2134e04d08907262ad Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9CWill?= <“gia19001@byui.edu”>
Date: Wed, 18 Feb 2026 13:55:09 -0700
Subject: [PATCH 4/7] Update #611 test to use setup context (snapshot_path,
 migration_path)

---
 test/migration_generator_test.exs | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/test/migration_generator_test.exs b/test/migration_generator_test.exs
index 6452c0f0..2f6a7368 100644
--- a/test/migration_generator_test.exs
+++ b/test/migration_generator_test.exs
@@ -1817,7 +1817,10 @@ defmodule AshPostgres.MigrationGeneratorTest do
       assert File.read!(file) =~ ~S{create index(:posts, [:post_id])}
     end
 
-    test "changing only reference index? does not drop and re-add foreign key (issue #611)" do
+    test "changing only reference index? does not drop and re-add foreign key (issue #611)", %{
+      snapshot_path: snapshot_path,
+      migration_path: migration_path
+    } do
       # First generate: reference with index?: true
       defresource PostRefIdx, "posts" do
         attributes do
@@ -1862,8 +1865,8 @@ defmodule AshPostgres.MigrationGeneratorTest do
       end
 
       AshPostgres.MigrationGenerator.generate(DomainRefIdx,
-        snapshot_path: "test_snapshots_path",
-        migration_path: "test_migration_path",
+        snapshot_path: snapshot_path,
+        migration_path: migration_path,
         quiet: true,
         format: false,
         auto_name: true
@@ -1913,15 +1916,15 @@ defmodule AshPostgres.MigrationGeneratorTest do
       end
 
       AshPostgres.MigrationGenerator.generate(DomainRefNoIdx,
-        snapshot_path: "test_snapshots_path",
-        migration_path: "test_migration_path",
+        snapshot_path: snapshot_path,
+        migration_path: migration_path,
         quiet: true,
         format: false,
         auto_name: true
       )
 
       [_, file2] =
-        Path.wildcard("test_migration_path/**/*_migrate_resources*.exs")
+        Path.wildcard("#{migration_path}/**/*_migrate_resources*.exs")
         |> Enum.reject(&String.contains?(&1, "extensions"))
         |> Enum.sort()
 

From 7765d59b1e87dfe08817dee933f90b59449ee6b8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9CWill?= <“gia19001@byui.edu”>
Date: Mon, 2 Mar 2026 14:08:31 -0700
Subject: [PATCH 5/7] Ensure identity unique indexes precede self-referential
 foreign keys

---
 .../migration_generator.ex                    | 84 ++++++++++++++++++-
 lib/migration_generator/operation.ex          |  1 +
 test/migration_generator_test.exs             | 79 +++++++++++++++++
 3 files changed, 162 insertions(+), 2 deletions(-)

diff --git a/lib/migration_generator/migration_generator.ex b/lib/migration_generator/migration_generator.ex
index 1d0af41b..d1bb0e2d 100644
--- a/lib/migration_generator/migration_generator.ex
+++ b/lib/migration_generator/migration_generator.ex
@@ -1518,6 +1518,76 @@ defmodule AshPostgres.MigrationGenerator do
     true
   end
 
+  # CreateTable must appear before AddUniqueIndex for the same table (table must exist first).
+  defp after?(
+         %Operation.CreateTable{table: table, schema: schema},
+         %Operation.AddUniqueIndex{table: table, schema: schema}
+       ),
+       do: false
+
+  # Unique index must be created before any alter that adds FKs referencing it (issue #236).
+  defp after?(
+         %Operation.AddUniqueIndex{table: table, schema: schema},
+         %Operation.AlterAttribute{table: table, schema: schema}
+       ),
+       do: false
+
+  # Do not place AddUniqueIndex after CreateTable (must be after columns are added).
+  defp after?(
+         %Operation.AddUniqueIndex{table: table, schema: schema},
+         %Operation.CreateTable{table: table, schema: schema}
+       ),
+       do: false
+
+  # Place AddUniqueIndex after the last AddAttribute for the same table so it
+  # appears before AlterAttributes (issue #236).
+  defp after?(
+         %Operation.AddUniqueIndex{
+           insert_after_attribute_order: max_order,
+           table: table,
+           schema: schema
+         },
+         %Operation.AddAttribute{
+           table: table,
+           schema: schema,
+           attribute: %{order: order}
+         }
+       )
+       when not is_nil(max_order) and order == max_order,
+       do: true
+
+  defp after?(
+         %Operation.AddUniqueIndex{
+           insert_after_attribute_order: max_order,
+           table: table,
+           schema: schema
+         },
+         %Operation.AddAttribute{
+           table: table,
+           schema: schema,
+           attribute: %{order: order}
+         }
+       )
+       when not is_nil(max_order) and order != max_order,
+       do: false
+
+  defp after?(
+         %Operation.AddUniqueIndex{
+           identity: %{keys: keys},
+           table: table,
+           schema: schema
+         },
+         %Operation.AlterAttribute{
+           table: table,
+           schema: schema,
+           new_attribute: %{
+             references: %{table: table, destination_attribute: destination_attribute}
+           }
+         }
+       ) do
+    destination_attribute not in List.wrap(keys)
+  end
+
   defp after?(
          %Operation.AddUniqueIndex{
            table: table,
@@ -2267,6 +2337,7 @@ defmodule AshPostgres.MigrationGenerator do
           identity: identity,
           schema: snapshot.schema,
           table: snapshot.table,
+          insert_after_attribute_order: max(0, length(snapshot.attributes) - 1),
           concurrently: opts.concurrent_indexes
         }
       end)
@@ -2301,13 +2372,22 @@ defmodule AshPostgres.MigrationGenerator do
         }
       end)
 
+    # Place unique indexes after create/add attributes but before alter attributes
+    # so FKs that reference identity columns see the unique index (issue #236).
+    {creates_and_adds, alter_and_rest} =
+      Enum.split_while(attribute_operations, fn
+        %Operation.AlterAttribute{} -> false
+        _ -> true
+      end)
+
     [
       pkey_operations,
       unique_indexes_to_remove,
-      attribute_operations,
+      creates_and_adds,
+      unique_indexes_to_add,
+      alter_and_rest,
       reference_indexes_to_add,
       reference_indexes_to_remove,
-      unique_indexes_to_add,
       unique_indexes_to_rename,
       constraints_to_remove,
       constraints_to_add,
diff --git a/lib/migration_generator/operation.ex b/lib/migration_generator/operation.ex
index 978298d3..405baba7 100644
--- a/lib/migration_generator/operation.ex
+++ b/lib/migration_generator/operation.ex
@@ -862,6 +862,7 @@ defmodule AshPostgres.MigrationGenerator.Operation do
       :schema,
       :multitenancy,
       :old_multitenancy,
+      :insert_after_attribute_order,
       no_phase: true,
       concurrently: false
     ]
diff --git a/test/migration_generator_test.exs b/test/migration_generator_test.exs
index 2f6a7368..43cc11f0 100644
--- a/test/migration_generator_test.exs
+++ b/test/migration_generator_test.exs
@@ -99,6 +99,13 @@ defmodule AshPostgres.MigrationGeneratorTest do
     end
   end
 
+  defp position_of_substring(string, substring) do
+    case :binary.match(string, substring) do
+      {pos, _len} -> pos
+      :nomatch -> nil
+    end
+  end
+
   defmacrop defresource(mod, table, do: body) do
     quote do
       Code.compiler_options(ignore_module_conflict: true)
@@ -1677,6 +1684,78 @@ defmodule AshPostgres.MigrationGeneratorTest do
                ~S[references(:posts, column: :id, name: "posts_post_id_fkey", type: :uuid, prefix: "public")]
     end
 
+    @tag :issue_236
+    test "unique index is created before dependent foreign key (issue #236)", %{
+      snapshot_path: snapshot_path,
+      migration_path: migration_path
+    } do
+      defresource Template, "templates" do
+        attributes do
+          uuid_primary_key(:id)
+        end
+      end
+
+      defresource Phase, "phases" do
+        attributes do
+          uuid_primary_key(:id)
+        end
+      end
+
+      defresource TemplatePhase, "template_phase" do
+        attributes do
+          uuid_primary_key(:id)
+          attribute(:name, :string, allow_nil?: false, public?: true)
+        end
+
+        identities do
+          identity(:id, [:id])
+        end
+
+        relationships do
+          belongs_to(:template, Template, primary_key?: true, allow_nil?: false, public?: true)
+          belongs_to(:phase, Phase, primary_key?: true, allow_nil?: false, public?: true)
+
+          belongs_to(:template_phase, __MODULE__) do
+            source_attribute(:follows)
+            destination_attribute(:id)
+            attribute_writable?(true)
+            allow_nil?(true)
+            public?(true)
+          end
+        end
+      end
+
+      defdomain([Template, Phase, TemplatePhase])
+
+      AshPostgres.MigrationGenerator.generate(Domain,
+        snapshot_path: snapshot_path,
+        migration_path: migration_path,
+        quiet: true,
+        format: false,
+        auto_name: true
+      )
+
+      assert [file] =
+               Path.wildcard("#{migration_path}/**/*_migrate_resources*.exs")
+               |> Enum.reject(&String.contains?(&1, "extensions"))
+
+      file_contents = File.read!(file)
+
+      unique_index_pos =
+        position_of_substring(
+          file_contents,
+          ~S{create unique_index(:template_phase, [:id], name: "template_phase_id_index")}
+        )
+
+      follows_fk_pos = position_of_substring(file_contents, "references(:template_phase")
+
+      assert unique_index_pos && follows_fk_pos,
+             "expected migration to contain both the unique index and the follows foreign key"
+
+      assert unique_index_pos < follows_fk_pos,
+             "expected unique index creation to appear before the follows foreign key modification"
+    end
+
     test "references are inferred automatically if the attribute has a different type", %{
       snapshot_path: snapshot_path,
       migration_path: migration_path

From 48c2be5193b4f9572c85391c0d7594493173c4f6 Mon Sep 17 00:00:00 2001
From: Zach Daniel <zachary.s.daniel@gmail.com>
Date: Tue, 3 Mar 2026 06:24:15 -0500
Subject: [PATCH 6/7] Apply suggestion from @zachdaniel

---
 lib/migration_generator/migration_generator.ex | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/migration_generator/migration_generator.ex b/lib/migration_generator/migration_generator.ex
index 9208bdf8..4eca73b7 100644
--- a/lib/migration_generator/migration_generator.ex
+++ b/lib/migration_generator/migration_generator.ex
@@ -1525,7 +1525,7 @@ defmodule AshPostgres.MigrationGenerator do
        ),
        do: false
 
-  # Unique index must be created before any alter that adds FKs referencing it (issue #236).
+  # Unique index must be created before any alter that adds FKs referencing it.
   defp after?(
          %Operation.AddUniqueIndex{table: table, schema: schema},
          %Operation.AlterAttribute{table: table, schema: schema}

From ec7988077b4b86125fa66d385624e24928b7d96f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9CWill?= <“gia19001@byui.edu”>
Date: Wed, 4 Mar 2026 13:23:31 -0700
Subject: [PATCH 7/7] Compute AddUniqueIndex order from identity keys

---
 lib/migration_generator/migration_generator.ex | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/lib/migration_generator/migration_generator.ex b/lib/migration_generator/migration_generator.ex
index 4eca73b7..bbd9b573 100644
--- a/lib/migration_generator/migration_generator.ex
+++ b/lib/migration_generator/migration_generator.ex
@@ -2333,11 +2333,22 @@ defmodule AshPostgres.MigrationGenerator do
         end)
       end
       |> Enum.map(fn identity ->
+        orders =
+          identity.keys
+          |> Enum.map(&Enum.find_index(snapshot.attributes, fn attr -> attr.source == &1 end))
+          |> Enum.reject(&is_nil/1)
+
+        insert_after_attribute_order =
+          case orders do
+            [] -> nil
+            _ -> Enum.max(orders)
+          end
+
         %Operation.AddUniqueIndex{
           identity: identity,
           schema: snapshot.schema,
           table: snapshot.table,
-          insert_after_attribute_order: max(0, length(snapshot.attributes) - 1),
+          insert_after_attribute_order: insert_after_attribute_order,
           concurrently: opts.concurrent_indexes
         }
       end)