improvement: add show_keysets_for_all_actions? configuration

It is quite expensive to load fields when they won't be used, and
ultimately it is unlikely that we will want to use the keyset retrieved
from an action that isn't performing keyset pagination.

config/config.exs

@@ -29,6 +29,7 @@ if Mix.env() == :test do
     Ash.Test.Support.PolicySimple.Domain
   ]
 
+  config :ash, :show_keysets_for_all_actions?, false
   config :ash, :policies, no_filter_static_forbidden_reads?: false
 
   config :ash, :custom_expressions, [Ash.Test.Expressions.JaroDistance]

lib/ash/actions/read/read.ex

@@ -214,7 +214,12 @@ defmodule Ash.Actions.Read do
     opts = Keyword.delete(opts, :page)
     query = Ash.Query.page(query, page_opts)
 
-    query = load_and_select_sort(query)
+    query =
+      if opts[:initial_data] do
+        query
+      else
+        load_and_select_sort(query, page_opts)
+      end
 
     query = add_relationship_count_aggregates(query)
 
@@ -2604,21 +2609,9 @@ defmodule Ash.Actions.Read do
       end
 
     paginated =
-      cond do
-        page_opts[:before] || page_opts[:after] ->
-          keyset_pagination(query, pagination, page_opts)
-
-        page_opts[:offset] ->
-          limit_offset_pagination(query, pagination, page_opts)
-
-        pagination.offset? && pagination.keyset? ->
-          keyset_pagination(query, pagination, page_opts)
-
-        pagination.offset? ->
-          limit_offset_pagination(query, pagination, page_opts)
-
-        true ->
-          keyset_pagination(query, pagination, page_opts)
+      case pagination_type(page_opts, query.action.pagination) do
+        :keyset -> keyset_pagination(query, pagination, page_opts)
+        :offset -> limit_offset_pagination(query, pagination, page_opts)
       end
 
     case paginated do
@@ -2634,6 +2627,30 @@ defmodule Ash.Actions.Read do
     end
   end
 
+  defp pagination_type(_page_opts, pagination) when pagination in [nil, false], do: nil
+
+  defp pagination_type(page_opts, pagination) do
+    cond do
+      !page_opts ->
+        nil
+
+      page_opts[:before] || page_opts[:after] ->
+        :keyset
+
+      page_opts[:offset] ->
+        :offset
+
+      pagination.keyset? ->
+        :keyset
+
+      pagination.offset? ->
+        :offset
+
+      true ->
+        nil
+    end
+  end
+
   defp keyset_pagination(query, pagination, opts) do
     limited = Ash.Query.limit(query, limit(query, opts[:limit], query.limit, pagination) + 1)
 
@@ -2677,18 +2694,35 @@ defmodule Ash.Actions.Read do
     end
   end
 
-  defp load_and_select_sort(query) do
-    query.resource
-    |> Ash.Resource.Info.actions()
-    |> Enum.any?(&match?(%{pagination: %{keyset?: true}}, &1))
-    |> if do
-      query.sort
-      |> Enum.map(&elem(&1, 0))
-      |> then(fn load ->
-        Ash.Query.load(query, load)
-      end)
+  defp load_and_select_sort(query, page_opts) do
+    if Application.get_env(:ash, :show_keysets_for_all_actions?, true) do
+      # in 4.0 remove this branch
+      show_keyset? =
+        query.resource
+        |> Ash.Resource.Info.actions()
+        |> Enum.any?(&match?(%{pagination: %{keyset?: true}}, &1))
+
+      if show_keyset? do
+        query.sort
+        |> Enum.map(&elem(&1, 0))
+        |> then(fn load ->
+          Ash.Query.load(query, load)
+        end)
+      else
+        false
+      end
     else
-      query
+      case pagination_type(page_opts, query.action.pagination) do
+        :keyset ->
+          query.sort
+          |> Enum.map(&elem(&1, 0))
+          |> then(fn load ->
+            Ash.Query.load(query, load)
+          end)
+
+        _ ->
+          query
+      end
     end
   end
 

lib/mix/tasks/install/ash.install.ex

@@ -59,6 +59,12 @@ defmodule Mix.Tasks.Ash.Install do
       [:include_embedded_source_by_default?],
       false
     )
+    |> Igniter.Project.Config.configure(
+      "config.exs",
+      :ash,
+      [:show_keysets_for_all_actions?],
+      false
+    )
     |> Igniter.Project.Config.configure(
       "config.exs",
       :ash,