Add active_visitors column to imported_pages CH table (#4028)

priv/ingest_repo/migrations/20240419133926_add_active_visitors_to_imported_pages.exs

@@ -0,0 +1,19 @@
+defmodule Plausible.IngestRepo.Migrations.AddActiveVisitorsToImportedPages do
+  use Ecto.Migration
+
+  def up do
+    execute """
+    ALTER TABLE imported_pages
+    #{Plausible.MigrationUtils.on_cluster_statement("imported_pages")}
+    ADD COLUMN active_visitors UInt64
+    """
+  end
+
+  def down do
+    execute """
+    ALTER TABLE imported_pages
+    #{Plausible.MigrationUtils.on_cluster_statement("imported_pages")}
+    DROP COLUMN active_visitors
+    """
+  end
+end