Merge branch 'feature/akkoma-prune-old-posts' into 'develop'

add options to mix prune_objects to delete more things

See merge request pleroma/pleroma!3952

changelog.d/akkoma-prune-options.add

@@ -0,0 +1 @@
+Add options to the mix prune_objects task

docs/administration/CLI_tasks/database.md

@@ -21,16 +21,18 @@ Replaces embedded objects with references to them in the `objects` table. Only n
     mix pleroma.database remove_embedded_objects [option ...]
     ```
 
-
 ### Options
 - `--vacuum` - run `VACUUM FULL` after the embedded objects are replaced with their references
 
 ## Prune old remote posts from the database
 
-This will prune remote posts older than 90 days (configurable with [`config :pleroma, :instance, remote_post_retention_days`](../../configuration/cheatsheet.md#instance)) from the database, they will be refetched from source when accessed.
+This will prune remote posts older than 90 days (configurable with [`config :pleroma, :instance, remote_post_retention_days`](../../configuration/cheatsheet.md#instance)) from the database. Pruned posts may be refetched in some cases.
+
+!!! note
+    The disk space will only be reclaimed after a proper vacuum. By default Postgresql does this for you on a regular basis, but if your instance has been running for a long time and there are many rows deleted, it may be advantageous to use `VACUUM FULL` (e.g. by using the `--vacuum` option).
 
 !!! danger
-    The disk space will only be reclaimed after `VACUUM FULL`. You may run out of disk space during the execution of the task or vacuuming if you don't have about 1/3rds of the database size free.
+    You may run out of disk space during the execution of the task or vacuuming if you don't have about 1/3rds of the database size free. Vacuum causes a substantial increase in I/O traffic, and may lead to a degraded experience while it is running.
 
 === "OTP"
 
@@ -45,7 +47,11 @@ This will prune remote posts older than 90 days (configurable with [`config :ple
     ```
 
 ### Options
-- `--vacuum` - run `VACUUM FULL` after the objects are pruned
+
+- `--keep-threads` - Don't prune posts when they are part of a thread where at least one post has seen local interaction (e.g. one of the posts is a local post, or is favourited by a local user, or has been repeated by a local user...). It also won't delete posts when at least one of the posts in that thread is kept (e.g. because one of the posts has seen recent activity).
+- `--keep-non-public` - Keep non-public posts like DM's and followers-only, even if they are remote.
+- `--prune-orphaned-activities` - Also prune orphaned activities afterwards. Activities are things like Like, Create, Announce, Flag (aka reports). They can significantly help reduce the database size.  Note: this can take a very long time.
+- `--vacuum` - Run `VACUUM FULL` after the objects are pruned. This should not be used on a regular basis, but is useful if your instance has been running for a long time before pruning.
 
 ## Create a conversation for all existing DMs
 
@@ -93,6 +99,9 @@ Can be safely re-run
 
 ## Vacuum the database
 
+!!! note
+    By default Postgresql has an autovacuum deamon running. While the tasks described here can help in some cases, they shouldn't be needed on a regular basis. See [the Postgresql docs on vacuuming](https://www.postgresql.org/docs/current/sql-vacuum.html) for more information on this.
+
 ### Analyze
 
 Running an `analyze` vacuum job can improve performance by updating statistics used by the query planner. **It is safe to cancel this.**

lib/mix/tasks/pleroma/database.ex

@@ -67,43 +67,168 @@ def run(["prune_objects" | args]) do
       OptionParser.parse(
         args,
         strict: [
-          vacuum: :boolean
+          vacuum: :boolean,
+          keep_threads: :boolean,
+          keep_non_public: :boolean,
+          prune_orphaned_activities: :boolean
         ]
       )
 
     start_pleroma()
 
     deadline = Pleroma.Config.get([:instance, :remote_post_retention_days])
+    time_deadline = NaiveDateTime.utc_now() |> NaiveDateTime.add(-(deadline * 86_400))
 
-    Logger.info("Pruning objects older than #{deadline} days")
+    log_message = "Pruning objects older than #{deadline} days"
 
-    time_deadline =
+    log_message =
-      NaiveDateTime.utc_now()
+      if Keyword.get(options, :keep_non_public) do
-      |> NaiveDateTime.add(-(deadline * 86_400))
+        log_message <> ", keeping non public posts"
+      else
+        log_message
+      end
 
-    from(o in Object,
+    log_message =
-      where:
+      if Keyword.get(options, :keep_threads) do
-        fragment(
+        log_message <> ", keeping threads intact"
-          "?->'to' \\? ? OR ?->'cc' \\? ?",
+      else
-          o.data,
+        log_message
-          ^Pleroma.Constants.as_public(),
+      end
-          o.data,
+
-          ^Pleroma.Constants.as_public()
+    log_message =
-        ),
+      if Keyword.get(options, :prune_orphaned_activities) do
-      where: o.inserted_at < ^time_deadline,
+        log_message <> ", pruning orphaned activities"
-      where:
+      else
+        log_message
+      end
+
+    log_message =
+      if Keyword.get(options, :vacuum) do
+        log_message <>
+          ", doing a full vacuum (you shouldn't do this as a recurring maintanance task)"
+      else
+        log_message
+      end
+
+    Logger.info(log_message)
+
+    if Keyword.get(options, :keep_threads) do
+      # We want to delete objects from threads where
+      # 1. the newest post is still old
+      # 2. none of the activities is local
+      # 3. none of the activities is bookmarked
+      # 4. optionally none of the posts is non-public
+      deletable_context =
+        if Keyword.get(options, :keep_non_public) do
+          Pleroma.Activity
+          |> join(:left, [a], b in Pleroma.Bookmark, on: a.id == b.activity_id)
+          |> group_by([a], fragment("? ->> 'context'::text", a.data))
+          |> having(
+            [a],
+            not fragment(
+              # Posts (checked on Create Activity) is non-public
+              "bool_or((not(?->'to' \\? ? OR ?->'cc' \\? ?)) and ? ->> 'type' = 'Create')",
+              a.data,
+              ^Pleroma.Constants.as_public(),
+              a.data,
+              ^Pleroma.Constants.as_public(),
+              a.data
+            )
+          )
+        else
+          Pleroma.Activity
+          |> join(:left, [a], b in Pleroma.Bookmark, on: a.id == b.activity_id)
+          |> group_by([a], fragment("? ->> 'context'::text", a.data))
+        end
+        |> having([a], max(a.updated_at) < ^time_deadline)
+        |> having([a], not fragment("bool_or(?)", a.local))
+        |> having([_, b], fragment("max(?::text) is null", b.id))
+        |> select([a], fragment("? ->> 'context'::text", a.data))
+
+      Pleroma.Object
+      |> where([o], fragment("? ->> 'context'::text", o.data) in subquery(deletable_context))
+    else
+      if Keyword.get(options, :keep_non_public) do
+        Pleroma.Object
+        |> where(
+          [o],
+          fragment(
+            "?->'to' \\? ? OR ?->'cc' \\? ?",
+            o.data,
+            ^Pleroma.Constants.as_public(),
+            o.data,
+            ^Pleroma.Constants.as_public()
+          )
+        )
+      else
+        Pleroma.Object
+      end
+      |> where([o], o.updated_at < ^time_deadline)
+      |> where(
+        [o],
         fragment("split_part(?->>'actor', '/', 3) != ?", o.data, ^Pleroma.Web.Endpoint.host())
-    )
+      )
+    end
     |> Repo.delete_all(timeout: :infinity)
 
-    prune_hashtags_query = """
+    if !Keyword.get(options, :keep_threads) do
+      # Without the --keep-threads option, it's possible that bookmarked
+      # objects have been deleted. We remove the corresponding bookmarks.
+      """
+      delete from public.bookmarks
+      where id in (
+        select b.id from public.bookmarks b
+        left join public.activities a on b.activity_id = a.id
+        left join public.objects o on a."data" ->> 'object' = o.data ->> 'id'
+        where o.id is null
+      )
+      """
+      |> Repo.query([], timeout: :infinity)
+    end
+
+    if Keyword.get(options, :prune_orphaned_activities) do
+      # Prune activities who link to a single object
+      """
+      delete from public.activities
+      where id in (
+        select a.id from public.activities a
+        left join public.objects o on a.data ->> 'object' = o.data ->> 'id'
+        left join public.activities a2 on a.data ->> 'object' = a2.data ->> 'id'
+        left join public.users u  on a.data ->> 'object' = u.ap_id
+        where not a.local
+        and jsonb_typeof(a."data" -> 'object') = 'string'
+        and o.id is null
+        and a2.id is null
+        and u.id is null
+      )
+      """
+      |> Repo.query([], timeout: :infinity)
+
+      # Prune activities who link to an array of objects
+      """
+      delete from public.activities
+      where id in (
+        select a.id from public.activities a
+        join json_array_elements_text((a."data" -> 'object')::json) as j on jsonb_typeof(a."data" -> 'object') = 'array'
+        left join public.objects o on j.value = o.data ->> 'id'
+        left join public.activities a2 on j.value = a2.data ->> 'id'
+        left join public.users u  on j.value = u.ap_id
+        group by a.id
+        having max(o.data ->> 'id') is null
+        and max(a2.data ->> 'id') is null
+        and max(u.ap_id) is null
+      )
+      """
+      |> Repo.query([], timeout: :infinity)
+    end
+
+    """
     DELETE FROM hashtags AS ht
     WHERE NOT EXISTS (
       SELECT 1 FROM hashtags_objects hto
       WHERE ht.id = hto.hashtag_id)
     """
-
+    |> Repo.query()
-    Repo.query(prune_hashtags_query)
 
     if Keyword.get(options, :vacuum) do
       Maintenance.vacuum("full")

test/mix/tasks/pleroma/database_test.exs

@@ -7,6 +7,7 @@ defmodule Mix.Tasks.Pleroma.DatabaseTest do
   use Oban.Testing, repo: Pleroma.Repo
 
   alias Pleroma.Activity
+  alias Pleroma.Bookmark
   alias Pleroma.Object
   alias Pleroma.Repo
   alias Pleroma.User
@@ -45,28 +46,509 @@ test "it replaces objects with references" do
   end
 
   describe "prune_objects" do
-    test "it prunes old objects from the database" do
+    setup do
-      insert(:note)
       deadline = Pleroma.Config.get([:instance, :remote_post_retention_days]) + 1
 
-      date =
+      old_insert_date =
         Timex.now()
         |> Timex.shift(days: -deadline)
         |> Timex.to_naive_datetime()
         |> NaiveDateTime.truncate(:second)
 
-      %{id: id} =
+      %{old_insert_date: old_insert_date}
+    end
+
+    test "it prunes old objects from the database", %{old_insert_date: old_insert_date} do
+      insert(:note)
+
+      %{id: note_remote_public_id} =
         :note
         |> insert()
-        |> Ecto.Changeset.change(%{inserted_at: date})
+        |> Ecto.Changeset.change(%{updated_at: old_insert_date})
         |> Repo.update!()
 
-      assert length(Repo.all(Object)) == 2
+      note_remote_non_public =
+        %{id: note_remote_non_public_id, data: note_remote_non_public_data} =
+        :note
+        |> insert()
+
+      note_remote_non_public
+      |> Ecto.Changeset.change(%{
+        updated_at: old_insert_date,
+        data: note_remote_non_public_data |> update_in(["to"], fn _ -> [] end)
+      })
+      |> Repo.update!()
+
+      assert length(Repo.all(Object)) == 3
 
       Mix.Tasks.Pleroma.Database.run(["prune_objects"])
 
       assert length(Repo.all(Object)) == 1
-      refute Object.get_by_id(id)
+      refute Object.get_by_id(note_remote_public_id)
+      refute Object.get_by_id(note_remote_non_public_id)
+    end
+
+    test "it cleans up bookmarks", %{old_insert_date: old_insert_date} do
+      user = insert(:user)
+      {:ok, old_object_activity} = CommonAPI.post(user, %{status: "yadayada"})
+
+      Repo.one(Object)
+      |> Ecto.Changeset.change(%{updated_at: old_insert_date})
+      |> Repo.update!()
+
+      {:ok, new_object_activity} = CommonAPI.post(user, %{status: "yadayada"})
+
+      {:ok, _} = Bookmark.create(user.id, old_object_activity.id)
+      {:ok, _} = Bookmark.create(user.id, new_object_activity.id)
+
+      assert length(Repo.all(Object)) == 2
+      assert length(Repo.all(Bookmark)) == 2
+
+      Mix.Tasks.Pleroma.Database.run(["prune_objects"])
+
+      assert length(Repo.all(Object)) == 1
+      assert length(Repo.all(Bookmark)) == 1
+      refute Bookmark.get(user.id, old_object_activity.id)
+    end
+
+    test "with the --keep-non-public option it still keeps non-public posts even if they are not local",
+         %{old_insert_date: old_insert_date} do
+      insert(:note)
+
+      %{id: note_remote_id} =
+        :note
+        |> insert()
+        |> Ecto.Changeset.change(%{updated_at: old_insert_date})
+        |> Repo.update!()
+
+      note_remote_non_public =
+        %{data: note_remote_non_public_data} =
+        :note
+        |> insert()
+
+      note_remote_non_public
+      |> Ecto.Changeset.change(%{
+        updated_at: old_insert_date,
+        data: note_remote_non_public_data |> update_in(["to"], fn _ -> [] end)
+      })
+      |> Repo.update!()
+
+      assert length(Repo.all(Object)) == 3
+
+      Mix.Tasks.Pleroma.Database.run(["prune_objects", "--keep-non-public"])
+
+      assert length(Repo.all(Object)) == 2
+      refute Object.get_by_id(note_remote_id)
+    end
+
+    test "with the --keep-threads and --keep-non-public option it keeps old threads with non-public replies even if the interaction is not local",
+         %{old_insert_date: old_insert_date} do
+      # For non-public we only check Create Activities because only these are relevant for threads
+      # Flags are always non-public, Announces from relays can be non-public...
+
+      remote_user1 = insert(:user, local: false)
+      remote_user2 = insert(:user, local: false)
+
+      # Old remote non-public reply (should be kept)
+      {:ok, old_remote_post1_activity} =
+        CommonAPI.post(remote_user1, %{status: "some thing", local: false})
+
+      old_remote_post1_activity
+      |> Ecto.Changeset.change(%{local: false, updated_at: old_insert_date})
+      |> Repo.update!()
+
+      {:ok, old_remote_non_public_reply_activity} =
+        CommonAPI.post(remote_user2, %{
+          status: "some reply",
+          in_reply_to_status_id: old_remote_post1_activity.id
+        })
+
+      old_remote_non_public_reply_activity
+      |> Ecto.Changeset.change(%{
+        local: false,
+        updated_at: old_insert_date,
+        data: old_remote_non_public_reply_activity.data |> update_in(["to"], fn _ -> [] end)
+      })
+      |> Repo.update!()
+
+      # Old remote non-public Announce (should be removed)
+      {:ok, old_remote_post2_activity = %{data: %{"object" => old_remote_post2_id}}} =
+        CommonAPI.post(remote_user1, %{status: "some thing", local: false})
+
+      old_remote_post2_activity
+      |> Ecto.Changeset.change(%{local: false, updated_at: old_insert_date})
+      |> Repo.update!()
+
+      {:ok, old_remote_non_public_repeat_activity} =
+        CommonAPI.repeat(old_remote_post2_activity.id, remote_user2)
+
+      old_remote_non_public_repeat_activity
+      |> Ecto.Changeset.change(%{
+        local: false,
+        updated_at: old_insert_date,
+        data: old_remote_non_public_repeat_activity.data |> update_in(["to"], fn _ -> [] end)
+      })
+      |> Repo.update!()
+
+      assert length(Repo.all(Object)) == 3
+
+      Mix.Tasks.Pleroma.Database.run(["prune_objects", "--keep-threads", "--keep-non-public"])
+
+      Repo.all(Pleroma.Activity)
+      assert length(Repo.all(Object)) == 2
+      refute Object.get_by_ap_id(old_remote_post2_id)
+    end
+
+    test "with the --keep-threads option it still keeps non-old threads even with no local interactions" do
+      remote_user = insert(:user, local: false)
+      remote_user2 = insert(:user, local: false)
+
+      {:ok, remote_post_activity} =
+        CommonAPI.post(remote_user, %{status: "some thing", local: false})
+
+      {:ok, remote_post_reply_activity} =
+        CommonAPI.post(remote_user2, %{
+          status: "some reply",
+          in_reply_to_status_id: remote_post_activity.id
+        })
+
+      remote_post_activity
+      |> Ecto.Changeset.change(%{local: false})
+      |> Repo.update!()
+
+      remote_post_reply_activity
+      |> Ecto.Changeset.change(%{local: false})
+      |> Repo.update!()
+
+      assert length(Repo.all(Object)) == 2
+
+      Mix.Tasks.Pleroma.Database.run(["prune_objects", "--keep-threads"])
+
+      assert length(Repo.all(Object)) == 2
+    end
+
+    test "with the --keep-threads option it deletes old threads with no local interaction", %{
+      old_insert_date: old_insert_date
+    } do
+      remote_user = insert(:user, local: false)
+      remote_user2 = insert(:user, local: false)
+
+      {:ok, old_remote_post_activity} =
+        CommonAPI.post(remote_user, %{status: "some thing", local: false})
+
+      old_remote_post_activity
+      |> Ecto.Changeset.change(%{local: false, updated_at: old_insert_date})
+      |> Repo.update!()
+
+      {:ok, old_remote_post_reply_activity} =
+        CommonAPI.post(remote_user2, %{
+          status: "some reply",
+          in_reply_to_status_id: old_remote_post_activity.id
+        })
+
+      old_remote_post_reply_activity
+      |> Ecto.Changeset.change(%{local: false, updated_at: old_insert_date})
+      |> Repo.update!()
+
+      {:ok, old_favourite_activity} =
+        CommonAPI.favorite(remote_user2, old_remote_post_activity.id)
+
+      old_favourite_activity
+      |> Ecto.Changeset.change(%{local: false, updated_at: old_insert_date})
+      |> Repo.update!()
+
+      {:ok, old_repeat_activity} = CommonAPI.repeat(old_remote_post_activity.id, remote_user2)
+
+      old_repeat_activity
+      |> Ecto.Changeset.change(%{local: false, updated_at: old_insert_date})
+      |> Repo.update!()
+
+      assert length(Repo.all(Object)) == 2
+
+      Mix.Tasks.Pleroma.Database.run(["prune_objects", "--keep-threads"])
+
+      assert length(Repo.all(Object)) == 0
+    end
+
+    test "with the --keep-threads option it keeps old threads with local interaction", %{
+      old_insert_date: old_insert_date
+    } do
+      remote_user = insert(:user, local: false)
+      local_user = insert(:user, local: true)
+
+      # local reply
+      {:ok, old_remote_post1_activity} =
+        CommonAPI.post(remote_user, %{status: "some thing", local: false})
+
+      old_remote_post1_activity
+      |> Ecto.Changeset.change(%{local: false, updated_at: old_insert_date})
+      |> Repo.update!()
+
+      {:ok, old_local_post2_reply_activity} =
+        CommonAPI.post(local_user, %{
+          status: "some reply",
+          in_reply_to_status_id: old_remote_post1_activity.id
+        })
+
+      old_local_post2_reply_activity
+      |> Ecto.Changeset.change(%{local: true, updated_at: old_insert_date})
+      |> Repo.update!()
+
+      # local Like
+      {:ok, old_remote_post3_activity} =
+        CommonAPI.post(remote_user, %{status: "some thing", local: false})
+
+      old_remote_post3_activity
+      |> Ecto.Changeset.change(%{local: false, updated_at: old_insert_date})
+      |> Repo.update!()
+
+      {:ok, old_favourite_activity} = CommonAPI.favorite(local_user, old_remote_post3_activity.id)
+
+      old_favourite_activity
+      |> Ecto.Changeset.change(%{local: true, updated_at: old_insert_date})
+      |> Repo.update!()
+
+      # local Announce
+      {:ok, old_remote_post4_activity} =
+        CommonAPI.post(remote_user, %{status: "some thing", local: false})
+
+      old_remote_post4_activity
+      |> Ecto.Changeset.change(%{local: false, updated_at: old_insert_date})
+      |> Repo.update!()
+
+      {:ok, old_repeat_activity} = CommonAPI.repeat(old_remote_post4_activity.id, local_user)
+
+      old_repeat_activity
+      |> Ecto.Changeset.change(%{local: true, updated_at: old_insert_date})
+      |> Repo.update!()
+
+      assert length(Repo.all(Object)) == 4
+
+      Mix.Tasks.Pleroma.Database.run(["prune_objects", "--keep-threads"])
+
+      assert length(Repo.all(Object)) == 4
+    end
+
+    test "with the --keep-threads option it keeps old threads with bookmarked posts", %{
+      old_insert_date: old_insert_date
+    } do
+      remote_user = insert(:user, local: false)
+      local_user = insert(:user, local: true)
+
+      {:ok, old_remote_post_activity} =
+        CommonAPI.post(remote_user, %{status: "some thing", local: false})
+
+      old_remote_post_activity
+      |> Ecto.Changeset.change(%{local: false, updated_at: old_insert_date})
+      |> Repo.update!()
+
+      Pleroma.Bookmark.create(local_user.id, old_remote_post_activity.id)
+
+      assert length(Repo.all(Object)) == 1
+
+      Mix.Tasks.Pleroma.Database.run(["prune_objects", "--keep-threads"])
+
+      assert length(Repo.all(Object)) == 1
+    end
+
+    test "We don't have unexpected tables which may contain objects that are referenced by activities" do
+      # We can delete orphaned activities. For that we look for the objects
+      # they reference in the 'objects', 'activities', and 'users' table.
+      # If someone adds another table with objects (idk, maybe with separate
+      # relations, or collections or w/e), then we need to make sure we
+      # add logic for that in the 'prune_objects' task so that we don't
+      # wrongly delete their corresponding activities.
+      # So when someone adds (or removes) a table, this test will fail.
+      # Either the table contains objects which can be referenced from the
+      # activities table
+      # => in that case the prune_objects job should be adapted so we don't
+      #    delete activities who still have the referenced object.
+      # Or it doesn't contain objects which can be referenced from the activities table
+      # => in that case you can add/remove the table to/from this (sorted) list.
+
+      assert Repo.query!(
+               "SELECT table_name FROM information_schema.tables WHERE table_schema='public' AND table_type='BASE TABLE';"
+             ).rows
+             |> Enum.sort() == [
+               ["activities"],
+               ["announcement_read_relationships"],
+               ["announcements"],
+               ["apps"],
+               ["backups"],
+               ["bookmark_folders"],
+               ["bookmarks"],
+               ["chat_message_references"],
+               ["chats"],
+               ["config"],
+               ["conversation_participation_recipient_ships"],
+               ["conversation_participations"],
+               ["conversations"],
+               ["counter_cache"],
+               ["data_migration_failed_ids"],
+               ["data_migrations"],
+               ["deliveries"],
+               ["filters"],
+               ["following_relationships"],
+               ["hashtags"],
+               ["hashtags_objects"],
+               ["instances"],
+               ["lists"],
+               ["markers"],
+               ["mfa_tokens"],
+               ["moderation_log"],
+               ["notifications"],
+               ["oauth_authorizations"],
+               ["oauth_tokens"],
+               ["oban_jobs"],
+               ["oban_peers"],
+               ["objects"],
+               ["password_reset_tokens"],
+               ["push_subscriptions"],
+               ["registrations"],
+               ["report_notes"],
+               ["rich_media_card"],
+               ["rules"],
+               ["scheduled_activities"],
+               ["schema_migrations"],
+               ["thread_mutes"],
+               # ["user_follows_hashtag"],                  # not in pleroma
+               # ["user_frontend_setting_profiles"],        # not in pleroma
+               ["user_invite_tokens"],
+               ["user_notes"],
+               ["user_relationships"],
+               ["users"]
+             ]
+    end
+
+    test "it prunes orphaned activities with the --prune-orphaned-activities" do
+      # Add a remote activity which references an Object
+      %Object{} |> Map.merge(%{data: %{"id" => "object_for_activity"}}) |> Repo.insert()
+
+      %Activity{}
+      |> Map.merge(%{
+        local: false,
+        data: %{"id" => "remote_activity_with_object", "object" => "object_for_activity"}
+      })
+      |> Repo.insert()
+
+      # Add a remote activity which references an activity
+      %Activity{}
+      |> Map.merge(%{
+        local: false,
+        data: %{
+          "id" => "remote_activity_with_activity",
+          "object" => "remote_activity_with_object"
+        }
+      })
+      |> Repo.insert()
+
+      # Add a remote activity which references an Actor
+      %User{} |> Map.merge(%{ap_id: "actor"}) |> Repo.insert()
+
+      %Activity{}
+      |> Map.merge(%{
+        local: false,
+        data: %{"id" => "remote_activity_with_actor", "object" => "actor"}
+      })
+      |> Repo.insert()
+
+      # Add a remote activity without existing referenced object, activity or actor
+      %Activity{}
+      |> Map.merge(%{
+        local: false,
+        data: %{
+          "id" => "remote_activity_without_existing_referenced_object",
+          "object" => "non_existing"
+        }
+      })
+      |> Repo.insert()
+
+      # Add a local activity without existing referenced object, activity or actor
+      %Activity{}
+      |> Map.merge(%{
+        local: true,
+        data: %{"id" => "local_activity_with_actor", "object" => "non_existing"}
+      })
+      |> Repo.insert()
+
+      # The remote activities without existing reference,
+      # and only the remote activities without existing reference, are deleted
+      # if, and only if, we provide the --prune-orphaned-activities option
+      assert length(Repo.all(Activity)) == 5
+      Mix.Tasks.Pleroma.Database.run(["prune_objects"])
+      assert length(Repo.all(Activity)) == 5
+      Mix.Tasks.Pleroma.Database.run(["prune_objects", "--prune-orphaned-activities"])
+      activities = Repo.all(Activity)
+
+      assert "remote_activity_without_existing_referenced_object" not in Enum.map(
+               activities,
+               fn a -> a.data["id"] end
+             )
+
+      assert length(activities) == 4
+    end
+
+    test "it prunes orphaned activities with the --prune-orphaned-activities when the objects are referenced from an array" do
+      %Object{} |> Map.merge(%{data: %{"id" => "existing_object"}}) |> Repo.insert()
+      %User{} |> Map.merge(%{ap_id: "existing_actor"}) |> Repo.insert()
+
+      # Multiple objects, one object exists (keep)
+      %Activity{}
+      |> Map.merge(%{
+        local: false,
+        data: %{
+          "id" => "remote_activity_existing_object",
+          "object" => ["non_ existing_object", "existing_object"]
+        }
+      })
+      |> Repo.insert()
+
+      # Multiple objects, one actor exists (keep)
+      %Activity{}
+      |> Map.merge(%{
+        local: false,
+        data: %{
+          "id" => "remote_activity_existing_actor",
+          "object" => ["non_ existing_object", "existing_actor"]
+        }
+      })
+      |> Repo.insert()
+
+      # Multiple objects, one activity exists (keep)
+      %Activity{}
+      |> Map.merge(%{
+        local: false,
+        data: %{
+          "id" => "remote_activity_existing_activity",
+          "object" => ["non_ existing_object", "remote_activity_existing_actor"]
+        }
+      })
+      |> Repo.insert()
+
+      # Multiple objects none exist (prune)
+      %Activity{}
+      |> Map.merge(%{
+        local: false,
+        data: %{
+          "id" => "remote_activity_without_existing_referenced_object",
+          "object" => ["owo", "whats_this"]
+        }
+      })
+      |> Repo.insert()
+
+      assert length(Repo.all(Activity)) == 4
+      Mix.Tasks.Pleroma.Database.run(["prune_objects"])
+      assert length(Repo.all(Activity)) == 4
+      Mix.Tasks.Pleroma.Database.run(["prune_objects", "--prune-orphaned-activities"])
+      activities = Repo.all(Activity)
+      assert length(activities) == 3
+
+      assert "remote_activity_without_existing_referenced_object" not in Enum.map(
+               activities,
+               fn a -> a.data["id"] end
+             )
+
+      assert length(activities) == 3
     end
   end