[#3213] Added `HashtagsTableMigrator.count/1`.

lib/pleroma/migrators/hashtags_table_migrator.ex

@@ -85,19 +85,8 @@ defmodule Pleroma.Migrators.HashtagsTableMigrator do
 
     max_processed_id = data_migration.data["max_processed_id"] || 0
 
-    # Note: most objects have Mention-type AS2 tags and no hashtags (but we can't filter them out)
-    from(
-      object in Object,
-      left_join: hashtag in assoc(object, :hashtags),
-      where: object.id > ^max_processed_id,
-      where: is_nil(hashtag.id),
-      where:
-        fragment("(?)->'tag' IS NOT NULL AND (?)->'tag' != '[]'::jsonb", object.data, object.data),
-      select: %{
-        id: object.id,
-        tag: fragment("(?)->'tag'", object.data)
-      }
-    )
+    query()
+    |> where([object], object.id > ^max_processed_id)
     |> Repo.chunk_stream(100, :batches, timeout: :infinity)
     |> Stream.each(fn objects ->
       object_ids = Enum.map(objects, & &1.id)
@@ -155,6 +144,21 @@ defmodule Pleroma.Migrators.HashtagsTableMigrator do
     {:noreply, state}
   end
 
+  defp query do
+    # Note: most objects have Mention-type AS2 tags and no hashtags (but we can't filter them out)
+    from(
+      object in Object,
+      left_join: hashtag in assoc(object, :hashtags),
+      where: is_nil(hashtag.id),
+      where:
+        fragment("(?)->'tag' IS NOT NULL AND (?)->'tag' != '[]'::jsonb", object.data, object.data),
+      select: %{
+        id: object.id,
+        tag: fragment("(?)->'tag'", object.data)
+      }
+    )
+  end
+
   defp transfer_object_hashtags(object) do
     hashtags = Object.object_data_hashtags(%{"tag" => object.tag})
 
@@ -188,6 +192,18 @@ defmodule Pleroma.Migrators.HashtagsTableMigrator do
     end)
   end
 
+  def count(force \\ false) do
+    stored_count = state()[:count]
+
+    if stored_count && !force do
+      stored_count
+    else
+      count = Repo.aggregate(query(), :count, :id)
+      put_stat(:count, count)
+      count
+    end
+  end
+
   defp persist_stats(data_migration) do
     runner_state = Map.drop(state(), [:status])
     _ = DataMigration.update(data_migration, %{data: runner_state})