Page Scroll Goals: migration step 3 (#5036)

* migration: add scroll_threshold to goals

* do not drop the old index yet

* add scroll_threshold field to goal schema + new unique constraint

* adjust test to test what it claims to

* mix format

* add migration

priv/repo/migrations/20250130121019_drop_unique_page_path_constraint_from_goals.exs

@@ -0,0 +1,22 @@
+defmodule Plausible.Repo.Migrations.DropUniquePagePathConstraintFromGoals do
+  use Ecto.Migration
+
+  @disable_ddl_transaction true
+  @disable_migration_lock true
+
+  # Plausible.Repo.Migrations.GoalsUnique
+  @old_index unique_index(
+               :goals,
+               [:site_id, :page_path],
+               where: "page_path IS NOT NULL",
+               name: :goals_page_path_unique
+             )
+
+  def up do
+    drop(@old_index)
+  end
+
+  def down do
+    create(@old_index)
+  end
+end