Merge branch 'feature/object-hashtags-rework' into 'develop'

Hashtags extraction from objects. Background migration infrastructure.

Closes #1840 and #2455

See merge request pleroma/pleroma!3213

24 files changed, 1068 insertions, 127 deletions

diff --git a/lib/mix/tasks/pleroma/database.ex b/lib/mix/tasks/pleroma/database.ex
index 2403ed581..e7f4b67a4 100644
--- a/lib/mix/tasks/pleroma/database.ex
+++ b/lib/mix/tasks/pleroma/database.ex
@@ -8,10 +8,13 @@ defmodule Mix.Tasks.Pleroma.Database do
   alias Pleroma.Object
   alias Pleroma.Repo
   alias Pleroma.User
+
   require Logger
   require Pleroma.Constants
+
   import Ecto.Query
   import Mix.Pleroma
+
   use Mix.Task
 
   @shortdoc "A collection of database related tasks"
@@ -214,4 +217,32 @@ defmodule Mix.Tasks.Pleroma.Database do
       shell_info('Done.')
     end
   end
+
+  # Rolls back a specific migration (leaving subsequent migrations applied).
+  # WARNING: imposes a risk of unrecoverable data loss — proceed at your own responsibility.
+  # Based on https://stackoverflow.com/a/53825840
+  def run(["rollback", version]) do
+    prompt = "SEVERE WARNING: this operation may result in unrecoverable data loss. Continue?"
+
+    if shell_prompt(prompt, "n") in ~w(Yn Y y) do
+      {_, result, _} =
+        Ecto.Migrator.with_repo(Pleroma.Repo, fn repo ->
+          version = String.to_integer(version)
+          re = ~r/^#{version}_.*\.exs/
+          path = Ecto.Migrator.migrations_path(repo)
+
+          with {_, "" <> file} <- {:find, Enum.find(File.ls!(path), &String.match?(&1, re))},
+               {_, [{mod, _} | _]} <- {:compile, Code.compile_file(Path.join(path, file))},
+               {_, :ok} <- {:rollback, Ecto.Migrator.down(repo, version, mod)} do
+            {:ok, "Reversed migration: #{file}"}
+          else
+            {:find, _} -> {:error, "No migration found with version prefix: #{version}"}
+            {:compile, e} -> {:error, "Problem compiling migration module: #{inspect(e)}"}
+            {:rollback, e} -> {:error, "Problem reversing migration: #{inspect(e)}"}
+          end
+        end)
+
+      shell_info(inspect(result))
+    end
+  end
 end
diff --git a/lib/pleroma/activity.ex b/lib/pleroma/activity.ex
index 6542e684e..d59403884 100644
--- a/lib/pleroma/activity.ex
+++ b/lib/pleroma/activity.ex
@@ -113,6 +113,7 @@ defmodule Pleroma.Activity do
     from([a] in query,
       left_join: b in Bookmark,
       on: b.user_id == ^user.id and b.activity_id == a.id,
+      as: :bookmark,
       preload: [bookmark: b]
     )
   end
@@ -123,6 +124,7 @@ defmodule Pleroma.Activity do
     from([a] in query,
       left_join: r in ReportNote,
       on: a.id == r.activity_id,
+      as: :report_note,
       preload: [report_notes: r]
     )
   end
diff --git a/lib/pleroma/activity/ir/topics.ex b/lib/pleroma/activity/ir/topics.ex
index d94395fc1..7a603a615 100644
--- a/lib/pleroma/activity/ir/topics.ex
+++ b/lib/pleroma/activity/ir/topics.ex
@@ -48,14 +48,12 @@ defmodule Pleroma.Activity.Ir.Topics do
     tags
   end
 
-  defp hashtags_to_topics(%{data: %{"tag" => tags}}) do
-    tags
-    |> Enum.filter(&is_bitstring(&1))
-    |> Enum.map(fn tag -> "hashtag:" <> tag end)
+  defp hashtags_to_topics(object) do
+    object
+    |> Object.hashtags()
+    |> Enum.map(fn hashtag -> "hashtag:" <> hashtag end)
   end
 
-  defp hashtags_to_topics(_), do: []
-
   defp remote_topics(%{local: true}), do: []
 
   defp remote_topics(%{actor: actor}) when is_binary(actor),
diff --git a/lib/pleroma/application.ex b/lib/pleroma/application.ex
index c853a2bb4..06d399b2e 100644
--- a/lib/pleroma/application.ex
+++ b/lib/pleroma/application.ex
@@ -103,9 +103,7 @@ defmodule Pleroma.Application do
         task_children(@mix_env) ++
         dont_run_in_test(@mix_env) ++
         chat_child(chat_enabled?()) ++
-        [
-          Pleroma.Gopher.Server
-        ]
+        [Pleroma.Gopher.Server]
 
     # See http://elixir-lang.org/docs/stable/elixir/Supervisor.html
     # for other strategies and supported options
@@ -230,6 +228,12 @@ defmodule Pleroma.Application do
          keys: :duplicate,
          partitions: System.schedulers_online()
        ]}
+    ] ++ background_migrators()
+  end
+
+  defp background_migrators do
+    [
+      Pleroma.Migrators.HashtagsTableMigrator
     ]
   end
 
diff --git a/lib/pleroma/config.ex b/lib/pleroma/config.ex
index 2e15a3719..54e332595 100644
--- a/lib/pleroma/config.ex
+++ b/lib/pleroma/config.ex
@@ -99,4 +99,8 @@ defmodule Pleroma.Config do
   def oauth_consumer_strategies, do: get([:auth, :oauth_consumer_strategies], [])
 
   def oauth_consumer_enabled?, do: oauth_consumer_strategies() != []
+
+  def feature_enabled?(feature_name) do
+    get([:features, feature_name]) not in [nil, false, :disabled, :auto]
+  end
 end
diff --git a/lib/pleroma/data_migration.ex b/lib/pleroma/data_migration.ex
new file mode 100644
index 000000000..1377af16e
--- /dev/null
+++ b/lib/pleroma/data_migration.ex
@@ -0,0 +1,45 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.DataMigration do
+  use Ecto.Schema
+
+  alias Pleroma.DataMigration
+  alias Pleroma.DataMigration.State
+  alias Pleroma.Repo
+
+  import Ecto.Changeset
+  import Ecto.Query
+
+  schema "data_migrations" do
+    field(:name, :string)
+    field(:state, State, default: :pending)
+    field(:feature_lock, :boolean, default: false)
+    field(:params, :map, default: %{})
+    field(:data, :map, default: %{})
+
+    timestamps()
+  end
+
+  def changeset(data_migration, params \\ %{}) do
+    data_migration
+    |> cast(params, [:name, :state, :feature_lock, :params, :data])
+    |> validate_required([:name])
+    |> unique_constraint(:name)
+  end
+
+  def update_one_by_id(id, params \\ %{}) do
+    with {1, _} <-
+           from(dm in DataMigration, where: dm.id == ^id)
+           |> Repo.update_all(set: params) do
+      :ok
+    end
+  end
+
+  def get_by_name(name) do
+    Repo.get_by(DataMigration, name: name)
+  end
+
+  def populate_hashtags_table, do: get_by_name("populate_hashtags_table")
+end
diff --git a/lib/pleroma/delivery.ex b/lib/pleroma/delivery.ex
index e8d536767..511d5cf58 100644
--- a/lib/pleroma/delivery.ex
+++ b/lib/pleroma/delivery.ex
@@ -9,7 +9,6 @@ defmodule Pleroma.Delivery do
   alias Pleroma.Object
   alias Pleroma.Repo
   alias Pleroma.User
-  alias Pleroma.User
 
   import Ecto.Changeset
   import Ecto.Query
diff --git a/lib/pleroma/ecto_enums.ex b/lib/pleroma/ecto_enums.ex
index f198cccb7..2a9addabc 100644
--- a/lib/pleroma/ecto_enums.ex
+++ b/lib/pleroma/ecto_enums.ex
@@ -17,3 +17,11 @@ defenum(Pleroma.FollowingRelationship.State,
   follow_accept: 2,
   follow_reject: 3
 )
+
+defenum(Pleroma.DataMigration.State,
+  pending: 1,
+  running: 2,
+  complete: 3,
+  failed: 4,
+  manual: 5
+)
diff --git a/lib/pleroma/hashtag.ex b/lib/pleroma/hashtag.ex
new file mode 100644
index 000000000..53e2e9c89
--- /dev/null
+++ b/lib/pleroma/hashtag.ex
@@ -0,0 +1,106 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Hashtag do
+  use Ecto.Schema
+
+  import Ecto.Changeset
+  import Ecto.Query
+
+  alias Ecto.Multi
+  alias Pleroma.Hashtag
+  alias Pleroma.Object
+  alias Pleroma.Repo
+
+  schema "hashtags" do
+    field(:name, :string)
+
+    many_to_many(:objects, Object, join_through: "hashtags_objects", on_replace: :delete)
+
+    timestamps()
+  end
+
+  def normalize_name(name) do
+    name
+    |> String.downcase()
+    |> String.trim()
+  end
+
+  def get_or_create_by_name(name) do
+    changeset = changeset(%Hashtag{}, %{name: name})
+
+    Repo.insert(
+      changeset,
+      on_conflict: [set: [name: get_field(changeset, :name)]],
+      conflict_target: :name,
+      returning: true
+    )
+  end
+
+  def get_or_create_by_names(names) when is_list(names) do
+    names = Enum.map(names, &normalize_name/1)
+    timestamp = NaiveDateTime.truncate(NaiveDateTime.utc_now(), :second)
+
+    structs =
+      Enum.map(names, fn name ->
+        %Hashtag{}
+        |> changeset(%{name: name})
+        |> Map.get(:changes)
+        |> Map.merge(%{inserted_at: timestamp, updated_at: timestamp})
+      end)
+
+    try do
+      with {:ok, %{query_op: hashtags}} <-
+             Multi.new()
+             |> Multi.insert_all(:insert_all_op, Hashtag, structs,
+               on_conflict: :nothing,
+               conflict_target: :name
+             )
+             |> Multi.run(:query_op, fn _repo, _changes ->
+               {:ok, Repo.all(from(ht in Hashtag, where: ht.name in ^names))}
+             end)
+             |> Repo.transaction() do
+        {:ok, hashtags}
+      else
+        {:error, _name, value, _changes_so_far} -> {:error, value}
+      end
+    rescue
+      e -> {:error, e}
+    end
+  end
+
+  def changeset(%Hashtag{} = struct, params) do
+    struct
+    |> cast(params, [:name])
+    |> update_change(:name, &normalize_name/1)
+    |> validate_required([:name])
+    |> unique_constraint(:name)
+  end
+
+  def unlink(%Object{id: object_id}) do
+    with {_, hashtag_ids} <-
+           from(hto in "hashtags_objects",
+             where: hto.object_id == ^object_id,
+             select: hto.hashtag_id
+           )
+           |> Repo.delete_all(),
+         {:ok, unreferenced_count} <- delete_unreferenced(hashtag_ids) do
+      {:ok, length(hashtag_ids), unreferenced_count}
+    end
+  end
+
+  @delete_unreferenced_query """
+  DELETE FROM hashtags WHERE id IN
+    (SELECT hashtags.id FROM hashtags
+      LEFT OUTER JOIN hashtags_objects
+        ON hashtags_objects.hashtag_id = hashtags.id
+      WHERE hashtags_objects.hashtag_id IS NULL AND hashtags.id = ANY($1));
+  """
+
+  def delete_unreferenced(ids) do
+    with {:ok, %{num_rows: deleted_count}} <- Repo.query(@delete_unreferenced_query, [ids]) do
+      {:ok, deleted_count}
+    end
+  end
+end
diff --git a/lib/pleroma/migrators/hashtags_table_migrator.ex b/lib/pleroma/migrators/hashtags_table_migrator.ex
new file mode 100644
index 000000000..b84058e11
--- /dev/null
+++ b/lib/pleroma/migrators/hashtags_table_migrator.ex
@@ -0,0 +1,208 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Migrators.HashtagsTableMigrator do
+  defmodule State do
+    use Pleroma.Migrators.Support.BaseMigratorState
+
+    @impl Pleroma.Migrators.Support.BaseMigratorState
+    defdelegate data_migration(), to: Pleroma.DataMigration, as: :populate_hashtags_table
+  end
+
+  use Pleroma.Migrators.Support.BaseMigrator
+
+  alias Pleroma.Hashtag
+  alias Pleroma.Migrators.Support.BaseMigrator
+  alias Pleroma.Object
+
+  @impl BaseMigrator
+  def feature_config_path, do: [:features, :improved_hashtag_timeline]
+
+  @impl BaseMigrator
+  def fault_rate_allowance, do: Config.get([:populate_hashtags_table, :fault_rate_allowance], 0)
+
+  @impl BaseMigrator
+  def perform do
+    data_migration_id = data_migration_id()
+    max_processed_id = get_stat(:max_processed_id, 0)
+
+    Logger.info("Transferring embedded hashtags to `hashtags` (from oid: #{max_processed_id})...")
+
+    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)
+
+      results = Enum.map(objects, &transfer_object_hashtags(&1))
+
+      failed_ids =
+        results
+        |> Enum.filter(&(elem(&1, 0) == :error))
+        |> Enum.map(&elem(&1, 1))
+
+      # Count of objects with hashtags: `{:noop, id}` is returned for objects having other AS2 tags
+      chunk_affected_count =
+        results
+        |> Enum.filter(&(elem(&1, 0) == :ok))
+        |> length()
+
+      for failed_id <- failed_ids do
+        _ =
+          Repo.query(
+            "INSERT INTO data_migration_failed_ids(data_migration_id, record_id) " <>
+              "VALUES ($1, $2) ON CONFLICT DO NOTHING;",
+            [data_migration_id, failed_id]
+          )
+      end
+
+      _ =
+        Repo.query(
+          "DELETE FROM data_migration_failed_ids " <>
+            "WHERE data_migration_id = $1 AND record_id = ANY($2)",
+          [data_migration_id, object_ids -- failed_ids]
+        )
+
+      max_object_id = Enum.at(object_ids, -1)
+
+      put_stat(:max_processed_id, max_object_id)
+      increment_stat(:iteration_processed_count, length(object_ids))
+      increment_stat(:processed_count, length(object_ids))
+      increment_stat(:failed_count, length(failed_ids))
+      increment_stat(:affected_count, chunk_affected_count)
+      put_stat(:records_per_second, records_per_second())
+      persist_state()
+
+      # A quick and dirty approach to controlling the load this background migration imposes
+      sleep_interval = Config.get([:populate_hashtags_table, :sleep_interval_ms], 0)
+      Process.sleep(sleep_interval)
+    end)
+    |> Stream.run()
+  end
+
+  @impl BaseMigrator
+  def query do
+    # Note: most objects have Mention-type AS2 tags and no hashtags (but we can't filter them out)
+    # Note: not checking activity type, expecting remove_non_create_objects_hashtags/_ to clean up
+    from(
+      object in Object,
+      where:
+        fragment("(?)->'tag' IS NOT NULL AND (?)->'tag' != '[]'::jsonb", object.data, object.data),
+      select: %{
+        id: object.id,
+        tag: fragment("(?)->'tag'", object.data)
+      }
+    )
+    |> join(:left, [o], hashtags_objects in fragment("SELECT object_id FROM hashtags_objects"),
+      on: hashtags_objects.object_id == o.id
+    )
+    |> where([_o, hashtags_objects], is_nil(hashtags_objects.object_id))
+  end
+
+  @spec transfer_object_hashtags(Map.t()) :: {:noop | :ok | :error, integer()}
+  defp transfer_object_hashtags(object) do
+    embedded_tags = if Map.has_key?(object, :tag), do: object.tag, else: object.data["tag"]
+    hashtags = Object.object_data_hashtags(%{"tag" => embedded_tags})
+
+    if Enum.any?(hashtags) do
+      transfer_object_hashtags(object, hashtags)
+    else
+      {:noop, object.id}
+    end
+  end
+
+  defp transfer_object_hashtags(object, hashtags) do
+    Repo.transaction(fn ->
+      with {:ok, hashtag_records} <- Hashtag.get_or_create_by_names(hashtags) do
+        maps = Enum.map(hashtag_records, &%{hashtag_id: &1.id, object_id: object.id})
+        base_error = "ERROR when inserting hashtags_objects for object with id #{object.id}"
+
+        try do
+          with {rows_count, _} when is_integer(rows_count) <-
+                 Repo.insert_all("hashtags_objects", maps, on_conflict: :nothing) do
+            object.id
+          else
+            e ->
+              Logger.error("#{base_error}: #{inspect(e)}")
+              Repo.rollback(object.id)
+          end
+        rescue
+          e ->
+            Logger.error("#{base_error}: #{inspect(e)}")
+            Repo.rollback(object.id)
+        end
+      else
+        e ->
+          error = "ERROR: could not create hashtags for object #{object.id}: #{inspect(e)}"
+          Logger.error(error)
+          Repo.rollback(object.id)
+      end
+    end)
+  end
+
+  @impl BaseMigrator
+  def retry_failed do
+    data_migration_id = data_migration_id()
+
+    failed_objects_query()
+    |> Repo.chunk_stream(100, :one)
+    |> Stream.each(fn object ->
+      with {res, _} when res != :error <- transfer_object_hashtags(object) do
+        _ =
+          Repo.query(
+            "DELETE FROM data_migration_failed_ids " <>
+              "WHERE data_migration_id = $1 AND record_id = $2",
+            [data_migration_id, object.id]
+          )
+      end
+    end)
+    |> Stream.run()
+
+    put_stat(:failed_count, failures_count())
+    persist_state()
+
+    force_continue()
+  end
+
+  defp failed_objects_query do
+    from(o in Object)
+    |> join(:inner, [o], dmf in fragment("SELECT * FROM data_migration_failed_ids"),
+      on: dmf.record_id == o.id
+    )
+    |> where([_o, dmf], dmf.data_migration_id == ^data_migration_id())
+    |> order_by([o], asc: o.id)
+  end
+
+  @doc """
+  Service func to delete `hashtags_objects` for legacy objects not associated with Create activity.
+  Also deletes unreferenced `hashtags` records (might occur after deletion of `hashtags_objects`).
+  """
+  def delete_non_create_activities_hashtags do
+    hashtags_objects_cleanup_query = """
+    DELETE FROM hashtags_objects WHERE object_id IN
+      (SELECT DISTINCT objects.id FROM objects
+        JOIN hashtags_objects ON hashtags_objects.object_id = objects.id LEFT JOIN activities
+          ON COALESCE(activities.data->'object'->>'id', activities.data->>'object') =
+            (objects.data->>'id')
+          AND activities.data->>'type' = 'Create'
+        WHERE activities.id IS NULL);
+    """
+
+    hashtags_cleanup_query = """
+    DELETE FROM hashtags WHERE id IN
+      (SELECT hashtags.id FROM hashtags
+        LEFT OUTER JOIN hashtags_objects
+          ON hashtags_objects.hashtag_id = hashtags.id
+        WHERE hashtags_objects.hashtag_id IS NULL);
+    """
+
+    {:ok, %{num_rows: hashtags_objects_count}} =
+      Repo.query(hashtags_objects_cleanup_query, [], timeout: :infinity)
+
+    {:ok, %{num_rows: hashtags_count}} =
+      Repo.query(hashtags_cleanup_query, [], timeout: :infinity)
+
+    {:ok, hashtags_objects_count, hashtags_count}
+  end
+end
diff --git a/lib/pleroma/migrators/support/base_migrator.ex b/lib/pleroma/migrators/support/base_migrator.ex
new file mode 100644
index 000000000..1f8a5402b
--- /dev/null
+++ b/lib/pleroma/migrators/support/base_migrator.ex
@@ -0,0 +1,210 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Migrators.Support.BaseMigrator do
+  @moduledoc """
+  Base background migrator functionality.
+  """
+
+  @callback perform() :: any()
+  @callback retry_failed() :: any()
+  @callback feature_config_path() :: list(atom())
+  @callback query() :: Ecto.Query.t()
+  @callback fault_rate_allowance() :: integer() | float()
+
+  defmacro __using__(_opts) do
+    quote do
+      use GenServer
+
+      require Logger
+
+      import Ecto.Query
+
+      alias __MODULE__.State
+      alias Pleroma.Config
+      alias Pleroma.Repo
+
+      @behaviour Pleroma.Migrators.Support.BaseMigrator
+
+      defdelegate data_migration(), to: State
+      defdelegate data_migration_id(), to: State
+      defdelegate state(), to: State
+      defdelegate persist_state(), to: State, as: :persist_to_db
+      defdelegate get_stat(key, value \\ nil), to: State, as: :get_data_key
+      defdelegate put_stat(key, value), to: State, as: :put_data_key
+      defdelegate increment_stat(key, increment), to: State, as: :increment_data_key
+
+      @reg_name {:global, __MODULE__}
+
+      def whereis, do: GenServer.whereis(@reg_name)
+
+      def start_link(_) do
+        case whereis() do
+          nil ->
+            GenServer.start_link(__MODULE__, nil, name: @reg_name)
+
+          pid ->
+            {:ok, pid}
+        end
+      end
+
+      @impl true
+      def init(_) do
+        {:ok, nil, {:continue, :init_state}}
+      end
+
+      @impl true
+      def handle_continue(:init_state, _state) do
+        {:ok, _} = State.start_link(nil)
+
+        data_migration = data_migration()
+        manual_migrations = Config.get([:instance, :manual_data_migrations], [])
+
+        cond do
+          Config.get(:env) == :test ->
+            update_status(:noop)
+
+          is_nil(data_migration) ->
+            message = "Data migration does not exist."
+            update_status(:failed, message)
+            Logger.error("#{__MODULE__}: #{message}")
+
+          data_migration.state == :manual or data_migration.name in manual_migrations ->
+            message = "Data migration is in manual execution or manual fix mode."
+            update_status(:manual, message)
+            Logger.warn("#{__MODULE__}: #{message}")
+
+          data_migration.state == :complete ->
+            on_complete(data_migration)
+
+          true ->
+            send(self(), :perform)
+        end
+
+        {:noreply, nil}
+      end
+
+      @impl true
+      def handle_info(:perform, state) do
+        State.reinit()
+
+        update_status(:running)
+        put_stat(:iteration_processed_count, 0)
+        put_stat(:started_at, NaiveDateTime.utc_now())
+
+        perform()
+
+        fault_rate = fault_rate()
+        put_stat(:fault_rate, fault_rate)
+        fault_rate_allowance = fault_rate_allowance()
+
+        cond do
+          fault_rate == 0 ->
+            set_complete()
+
+          is_float(fault_rate) and fault_rate <= fault_rate_allowance ->
+            message = """
+            Done with fault rate of #{fault_rate} which doesn't exceed #{fault_rate_allowance}.
+            Putting data migration to manual fix mode. Try running `#{__MODULE__}.retry_failed/0`.
+            """
+
+            Logger.warn("#{__MODULE__}: #{message}")
+            update_status(:manual, message)
+            on_complete(data_migration())
+
+          true ->
+            message = "Too many failures. Try running `#{__MODULE__}.retry_failed/0`."
+            Logger.error("#{__MODULE__}: #{message}")
+            update_status(:failed, message)
+        end
+
+        persist_state()
+        {:noreply, state}
+      end
+
+      defp on_complete(data_migration) do
+        if data_migration.feature_lock || feature_state() == :disabled do
+          Logger.warn(
+            "#{__MODULE__}: migration complete but feature is locked; consider enabling."
+          )
+
+          :noop
+        else
+          Config.put(feature_config_path(), :enabled)
+          :ok
+        end
+      end
+
+      @doc "Approximate count for current iteration (including processed records count)"
+      def count(force \\ false, timeout \\ :infinity) do
+        stored_count = get_stat(:count)
+
+        if stored_count && !force do
+          stored_count
+        else
+          processed_count = get_stat(:processed_count, 0)
+          max_processed_id = get_stat(:max_processed_id, 0)
+          query = where(query(), [entity], entity.id > ^max_processed_id)
+
+          count = Repo.aggregate(query, :count, :id, timeout: timeout) + processed_count
+          put_stat(:count, count)
+          persist_state()
+
+          count
+        end
+      end
+
+      def failures_count do
+        with {:ok, %{rows: [[count]]}} <-
+               Repo.query(
+                 "SELECT COUNT(record_id) FROM data_migration_failed_ids WHERE data_migration_id = $1;",
+                 [data_migration_id()]
+               ) do
+          count
+        end
+      end
+
+      def feature_state, do: Config.get(feature_config_path())
+
+      def force_continue do
+        send(whereis(), :perform)
+      end
+
+      def force_restart do
+        :ok = State.reset()
+        force_continue()
+      end
+
+      def set_complete do
+        update_status(:complete)
+        persist_state()
+        on_complete(data_migration())
+      end
+
+      defp update_status(status, message \\ nil) do
+        put_stat(:state, status)
+        put_stat(:message, message)
+      end
+
+      defp fault_rate do
+        with failures_count when is_integer(failures_count) <- failures_count() do
+          failures_count / Enum.max([get_stat(:affected_count, 0), 1])
+        else
+          _ -> :error
+        end
+      end
+
+      defp records_per_second do
+        get_stat(:iteration_processed_count, 0) / Enum.max([running_time(), 1])
+      end
+
+      defp running_time do
+        NaiveDateTime.diff(
+          NaiveDateTime.utc_now(),
+          get_stat(:started_at, NaiveDateTime.utc_now())
+        )
+      end
+    end
+  end
+end
diff --git a/lib/pleroma/migrators/support/base_migrator_state.ex b/lib/pleroma/migrators/support/base_migrator_state.ex
new file mode 100644
index 000000000..b698587f2
--- /dev/null
+++ b/lib/pleroma/migrators/support/base_migrator_state.ex
@@ -0,0 +1,117 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Migrators.Support.BaseMigratorState do
+  @moduledoc """
+  Base background migrator state functionality.
+  """
+
+  @callback data_migration() :: Pleroma.DataMigration.t()
+
+  defmacro __using__(_opts) do
+    quote do
+      use Agent
+
+      alias Pleroma.DataMigration
+
+      @behaviour Pleroma.Migrators.Support.BaseMigratorState
+      @reg_name {:global, __MODULE__}
+
+      def start_link(_) do
+        Agent.start_link(fn -> load_state_from_db() end, name: @reg_name)
+      end
+
+      def data_migration, do: raise("data_migration/0 is not implemented")
+      defoverridable data_migration: 0
+
+      defp load_state_from_db do
+        data_migration = data_migration()
+
+        data =
+          if data_migration do
+            Map.new(data_migration.data, fn {k, v} -> {String.to_atom(k), v} end)
+          else
+            %{}
+          end
+
+        %{
+          data_migration_id: data_migration && data_migration.id,
+          data: data
+        }
+      end
+
+      def persist_to_db do
+        %{data_migration_id: data_migration_id, data: data} = state()
+
+        if data_migration_id do
+          DataMigration.update_one_by_id(data_migration_id, data: data)
+        else
+          {:error, :nil_data_migration_id}
+        end
+      end
+
+      def reset do
+        %{data_migration_id: data_migration_id} = state()
+
+        with false <- is_nil(data_migration_id),
+             :ok <-
+               DataMigration.update_one_by_id(data_migration_id,
+                 state: :pending,
+                 data: %{}
+               ) do
+          reinit()
+        else
+          true -> {:error, :nil_data_migration_id}
+          e -> e
+        end
+      end
+
+      def reinit do
+        Agent.update(@reg_name, fn _state -> load_state_from_db() end)
+      end
+
+      def state do
+        Agent.get(@reg_name, & &1)
+      end
+
+      def get_data_key(key, default \\ nil) do
+        get_in(state(), [:data, key]) || default
+      end
+
+      def put_data_key(key, value) do
+        _ = persist_non_data_change(key, value)
+
+        Agent.update(@reg_name, fn state ->
+          put_in(state, [:data, key], value)
+        end)
+      end
+
+      def increment_data_key(key, increment \\ 1) do
+        Agent.update(@reg_name, fn state ->
+          initial_value = get_in(state, [:data, key]) || 0
+          updated_value = initial_value + increment
+          put_in(state, [:data, key], updated_value)
+        end)
+      end
+
+      defp persist_non_data_change(:state, value) do
+        with true <- get_data_key(:state) != value,
+             true <- value in Pleroma.DataMigration.State.__valid_values__(),
+             %{data_migration_id: data_migration_id} when not is_nil(data_migration_id) <-
+               state() do
+          DataMigration.update_one_by_id(data_migration_id, state: value)
+        else
+          false -> :ok
+          _ -> {:error, :nil_data_migration_id}
+        end
+      end
+
+      defp persist_non_data_change(_, _) do
+        nil
+      end
+
+      def data_migration_id, do: Map.get(state(), :data_migration_id)
+    end
+  end
+end
diff --git a/lib/pleroma/object.ex b/lib/pleroma/object.ex
index aaf123840..3ba749d1a 100644
--- a/lib/pleroma/object.ex
+++ b/lib/pleroma/object.ex
@@ -10,6 +10,7 @@ defmodule Pleroma.Object do
 
   alias Pleroma.Activity
   alias Pleroma.Config
+  alias Pleroma.Hashtag
   alias Pleroma.Object
   alias Pleroma.Object.Fetcher
   alias Pleroma.ObjectTombstone
@@ -28,6 +29,8 @@ defmodule Pleroma.Object do
   schema "objects" do
     field(:data, :map)
 
+    many_to_many(:hashtags, Hashtag, join_through: "hashtags_objects", on_replace: :delete)
+
     timestamps()
   end
 
@@ -49,7 +52,8 @@ defmodule Pleroma.Object do
   end
 
   def create(data) do
-    Object.change(%Object{}, %{data: data})
+    %Object{}
+    |> Object.change(%{data: data})
     |> Repo.insert()
   end
 
@@ -58,8 +62,41 @@ defmodule Pleroma.Object do
     |> cast(params, [:data])
     |> validate_required([:data])
     |> unique_constraint(:ap_id, name: :objects_unique_apid_index)
+    # Expecting `maybe_handle_hashtags_change/1` to run last:
+    |> maybe_handle_hashtags_change(struct)
+  end
+
+  # Note: not checking activity type (assuming non-legacy objects are associated with Create act.)
+  defp maybe_handle_hashtags_change(changeset, struct) do
+    with %Ecto.Changeset{valid?: true} <- changeset,
+         data_hashtags_change = get_change(changeset, :data),
+         {_, true} <- {:changed, hashtags_changed?(struct, data_hashtags_change)},
+         {:ok, hashtag_records} <-
+           data_hashtags_change
+           |> object_data_hashtags()
+           |> Hashtag.get_or_create_by_names() do
+      put_assoc(changeset, :hashtags, hashtag_records)
+    else
+      %{valid?: false} ->
+        changeset
+
+      {:changed, false} ->
+        changeset
+
+      {:error, _} ->
+        validate_change(changeset, :data, fn _, _ ->
+          [data: "error referencing hashtags"]
+        end)
+    end
+  end
+
+  defp hashtags_changed?(%Object{} = struct, %{"tag" => _} = data) do
+    Enum.sort(embedded_hashtags(struct)) !=
+      Enum.sort(object_data_hashtags(data))
   end
 
+  defp hashtags_changed?(_, _), do: false
+
   def get_by_id(nil), do: nil
   def get_by_id(id), do: Repo.get(Object, id)
 
@@ -187,9 +224,13 @@ defmodule Pleroma.Object do
   def swap_object_with_tombstone(object) do
     tombstone = make_tombstone(object)
 
-    object
-    |> Object.change(%{data: tombstone})
-    |> Repo.update()
+    with {:ok, object} <-
+           object
+           |> Object.change(%{data: tombstone})
+           |> Repo.update() do
+      Hashtag.unlink(object)
+      {:ok, object}
+    end
   end
 
   def delete(%Object{data: %{"id" => id}} = object) do
@@ -349,4 +390,39 @@ defmodule Pleroma.Object do
 
   def self_replies(object, opts \\ []),
     do: replies(object, Keyword.put(opts, :self_only, true))
+
+  def tags(%Object{data: %{"tag" => tags}}) when is_list(tags), do: tags
+
+  def tags(_), do: []
+
+  def hashtags(%Object{} = object) do
+    # Note: always using embedded hashtags regardless whether they are migrated to hashtags table
+    #   (embedded hashtags stay in sync anyways, and we avoid extra joins and preload hassle)
+    embedded_hashtags(object)
+  end
+
+  def embedded_hashtags(%Object{data: data}) do
+    object_data_hashtags(data)
+  end
+
+  def embedded_hashtags(_), do: []
+
+  def object_data_hashtags(%{"tag" => tags}) when is_list(tags) do
+    tags
+    |> Enum.filter(fn
+      %{"type" => "Hashtag"} = data -> Map.has_key?(data, "name")
+      plain_text when is_bitstring(plain_text) -> true
+      _ -> false
+    end)
+    |> Enum.map(fn
+      %{"name" => "#" <> hashtag} -> String.downcase(hashtag)
+      %{"name" => hashtag} -> String.downcase(hashtag)
+      hashtag when is_bitstring(hashtag) -> String.downcase(hashtag)
+    end)
+    |> Enum.uniq()
+    # Note: "" elements (plain text) might occur in `data.tag` for incoming objects
+    |> Enum.filter(&(&1 not in [nil, ""]))
+  end
+
+  def object_data_hashtags(_), do: []
 end
diff --git a/lib/pleroma/pagination.ex b/lib/pleroma/pagination.ex
index 0d24e1010..33e45a0eb 100644
--- a/lib/pleroma/pagination.ex
+++ b/lib/pleroma/pagination.ex
@@ -93,6 +93,7 @@ defmodule Pleroma.Pagination do
       max_id: :string,
       offset: :integer,
       limit: :integer,
+      skip_extra_order: :boolean,
       skip_order: :boolean
     }
 
@@ -114,6 +115,8 @@ defmodule Pleroma.Pagination do
 
   defp restrict(query, :order, %{skip_order: true}, _), do: query
 
+  defp restrict(%{order_bys: [_ | _]} = query, :order, %{skip_extra_order: true}, _), do: query
+
   defp restrict(query, :order, %{min_id: _}, table_binding) do
     order_by(
       query,
diff --git a/lib/pleroma/repo.ex b/lib/pleroma/repo.ex
index 4556352d0..b8ea06e33 100644
--- a/lib/pleroma/repo.ex
+++ b/lib/pleroma/repo.ex
@@ -8,6 +8,8 @@ defmodule Pleroma.Repo do
     adapter: Ecto.Adapters.Postgres,
     migration_timestamps: [type: :naive_datetime_usec]
 
+  use Ecto.Explain
+
   import Ecto.Query
   require Logger
 
@@ -63,8 +65,8 @@ defmodule Pleroma.Repo do
   iex> Pleroma.Repo.chunk_stream(Pleroma.Activity.Queries.by_actor(ap_id), 500, :batches)
   """
   @spec chunk_stream(Ecto.Query.t(), integer(), atom()) :: Enumerable.t()
-  def chunk_stream(query, chunk_size, returns_as \\ :one) do
-    # We don't actually need start and end funcitons of resource streaming,
+  def chunk_stream(query, chunk_size, returns_as \\ :one, query_options \\ []) do
+    # We don't actually need start and end functions of resource streaming,
     # but it seems to be the only way to not fetch records one-by-one and
     # have individual records be the elements of the stream, instead of
     # lists of records
@@ -76,7 +78,7 @@ defmodule Pleroma.Repo do
           |> order_by(asc: :id)
           |> where([r], r.id > ^last_id)
           |> limit(^chunk_size)
-          |> all()
+          |> all(query_options)
           |> case do
             [] ->
               {:halt, last_id}
diff --git a/lib/pleroma/web/activity_pub/activity_pub.ex b/lib/pleroma/web/activity_pub/activity_pub.ex
index 5b45e2ca1..230faf024 100644
--- a/lib/pleroma/web/activity_pub/activity_pub.ex
+++ b/lib/pleroma/web/activity_pub/activity_pub.ex
@@ -10,6 +10,7 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
   alias Pleroma.Conversation
   alias Pleroma.Conversation.Participation
   alias Pleroma.Filter
+  alias Pleroma.Hashtag
   alias Pleroma.Maps
   alias Pleroma.Notification
   alias Pleroma.Object
@@ -465,6 +466,23 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
     |> Repo.one()
   end
 
+  defp fetch_paginated_optimized(query, opts, pagination) do
+    # Note: tag-filtering funcs may apply "ORDER BY objects.id DESC",
+    #   and extra sorting on "activities.id DESC NULLS LAST" would worse the query plan
+    opts = Map.put(opts, :skip_extra_order, true)
+
+    Pagination.fetch_paginated(query, opts, pagination)
+  end
+
+  def fetch_activities(recipients, opts \\ %{}, pagination \\ :keyset) do
+    list_memberships = Pleroma.List.memberships(opts[:user])
+
+    fetch_activities_query(recipients ++ list_memberships, opts)
+    |> fetch_paginated_optimized(opts, pagination)
+    |> Enum.reverse()
+    |> maybe_update_cc(list_memberships, opts[:user])
+  end
+
   @spec fetch_public_or_unlisted_activities(map(), Pagination.type()) :: [Activity.t()]
   def fetch_public_or_unlisted_activities(opts \\ %{}, pagination \\ :keyset) do
     opts = Map.delete(opts, :user)
@@ -472,7 +490,7 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
     [Constants.as_public()]
     |> fetch_activities_query(opts)
     |> restrict_unlisted(opts)
-    |> Pagination.fetch_paginated(opts, pagination)
+    |> fetch_paginated_optimized(opts, pagination)
   end
 
   @spec fetch_public_activities(map(), Pagination.type()) :: [Activity.t()]
@@ -693,51 +711,143 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
 
   defp restrict_since(query, _), do: query
 
-  defp restrict_tag_reject(_query, %{tag_reject: _tag_reject, skip_preload: true}) do
-    raise "Can't use the child object without preloading!"
+  defp restrict_embedded_tag_all(_query, %{tag_all: _tag_all, skip_preload: true}) do
+    raise_on_missing_preload()
+  end
+
+  defp restrict_embedded_tag_all(query, %{tag_all: [_ | _] = tag_all}) do
+    from(
+      [_activity, object] in query,
+      where: fragment("(?)->'tag' \\?& (?)", object.data, ^tag_all)
+    )
+  end
+
+  defp restrict_embedded_tag_all(query, %{tag_all: tag}) when is_binary(tag) do
+    restrict_embedded_tag_any(query, %{tag: tag})
+  end
+
+  defp restrict_embedded_tag_all(query, _), do: query
+
+  defp restrict_embedded_tag_any(_query, %{tag: _tag, skip_preload: true}) do
+    raise_on_missing_preload()
+  end
+
+  defp restrict_embedded_tag_any(query, %{tag: [_ | _] = tag_any}) do
+    from(
+      [_activity, object] in query,
+      where: fragment("(?)->'tag' \\?| (?)", object.data, ^tag_any)
+    )
   end
 
-  defp restrict_tag_reject(query, %{tag_reject: [_ | _] = tag_reject}) do
+  defp restrict_embedded_tag_any(query, %{tag: tag}) when is_binary(tag) do
+    restrict_embedded_tag_any(query, %{tag: [tag]})
+  end
+
+  defp restrict_embedded_tag_any(query, _), do: query
+
+  defp restrict_embedded_tag_reject_any(_query, %{tag_reject: _tag_reject, skip_preload: true}) do
+    raise_on_missing_preload()
+  end
+
+  defp restrict_embedded_tag_reject_any(query, %{tag_reject: [_ | _] = tag_reject}) do
     from(
       [_activity, object] in query,
       where: fragment("not (?)->'tag' \\?| (?)", object.data, ^tag_reject)
     )
   end
 
-  defp restrict_tag_reject(query, _), do: query
+  defp restrict_embedded_tag_reject_any(query, %{tag_reject: tag_reject})
+       when is_binary(tag_reject) do
+    restrict_embedded_tag_reject_any(query, %{tag_reject: [tag_reject]})
+  end
 
-  defp restrict_tag_all(_query, %{tag_all: _tag_all, skip_preload: true}) do
-    raise "Can't use the child object without preloading!"
+  defp restrict_embedded_tag_reject_any(query, _), do: query
+
+  defp object_ids_query_for_tags(tags) do
+    from(hto in "hashtags_objects")
+    |> join(:inner, [hto], ht in Pleroma.Hashtag, on: hto.hashtag_id == ht.id)
+    |> where([hto, ht], ht.name in ^tags)
+    |> select([hto], hto.object_id)
+    |> distinct([hto], true)
+  end
+
+  defp restrict_hashtag_all(_query, %{tag_all: _tag, skip_preload: true}) do
+    raise_on_missing_preload()
+  end
+
+  defp restrict_hashtag_all(query, %{tag_all: [single_tag]}) do
+    restrict_hashtag_any(query, %{tag: single_tag})
   end
 
-  defp restrict_tag_all(query, %{tag_all: [_ | _] = tag_all}) do
+  defp restrict_hashtag_all(query, %{tag_all: [_ | _] = tags}) do
     from(
       [_activity, object] in query,
-      where: fragment("(?)->'tag' \\?& (?)", object.data, ^tag_all)
+      where:
+        fragment(
+          """
+          (SELECT array_agg(hashtags.name) FROM hashtags JOIN hashtags_objects
+            ON hashtags_objects.hashtag_id = hashtags.id WHERE hashtags.name = ANY(?)
+              AND hashtags_objects.object_id = ?) @> ?
+          """,
+          ^tags,
+          object.id,
+          ^tags
+        )
     )
   end
 
-  defp restrict_tag_all(query, _), do: query
+  defp restrict_hashtag_all(query, %{tag_all: tag}) when is_binary(tag) do
+    restrict_hashtag_all(query, %{tag_all: [tag]})
+  end
 
-  defp restrict_tag(_query, %{tag: _tag, skip_preload: true}) do
-    raise "Can't use the child object without preloading!"
+  defp restrict_hashtag_all(query, _), do: query
+
+  defp restrict_hashtag_any(_query, %{tag: _tag, skip_preload: true}) do
+    raise_on_missing_preload()
   end
 
-  defp restrict_tag(query, %{tag: tag}) when is_list(tag) do
+  defp restrict_hashtag_any(query, %{tag: [_ | _] = tags}) do
+    hashtag_ids =
+      from(ht in Hashtag, where: ht.name in ^tags, select: ht.id)
+      |> Repo.all()
+
+    # Note: NO extra ordering should be done on "activities.id desc nulls last" for optimal plan
     from(
       [_activity, object] in query,
-      where: fragment("(?)->'tag' \\?| (?)", object.data, ^tag)
+      join: hto in "hashtags_objects",
+      on: hto.object_id == object.id,
+      where: hto.hashtag_id in ^hashtag_ids,
+      distinct: [desc: object.id],
+      order_by: [desc: object.id]
     )
   end
 
-  defp restrict_tag(query, %{tag: tag}) when is_binary(tag) do
+  defp restrict_hashtag_any(query, %{tag: tag}) when is_binary(tag) do
+    restrict_hashtag_any(query, %{tag: [tag]})
+  end
+
+  defp restrict_hashtag_any(query, _), do: query
+
+  defp restrict_hashtag_reject_any(_query, %{tag_reject: _tag_reject, skip_preload: true}) do
+    raise_on_missing_preload()
+  end
+
+  defp restrict_hashtag_reject_any(query, %{tag_reject: [_ | _] = tags_reject}) do
     from(
       [_activity, object] in query,
-      where: fragment("(?)->'tag' \\? (?)", object.data, ^tag)
+      where: object.id not in subquery(object_ids_query_for_tags(tags_reject))
     )
   end
 
-  defp restrict_tag(query, _), do: query
+  defp restrict_hashtag_reject_any(query, %{tag_reject: tag_reject}) when is_binary(tag_reject) do
+    restrict_hashtag_reject_any(query, %{tag_reject: [tag_reject]})
+  end
+
+  defp restrict_hashtag_reject_any(query, _), do: query
+
+  defp raise_on_missing_preload do
+    raise "Can't use the child object without preloading!"
+  end
 
   defp restrict_recipients(query, [], _user), do: query
 
@@ -1098,6 +1208,26 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
 
   defp maybe_order(query, _), do: query
 
+  defp normalize_fetch_activities_query_opts(opts) do
+    Enum.reduce([:tag, :tag_all, :tag_reject], opts, fn key, opts ->
+      case opts[key] do
+        value when is_bitstring(value) ->
+          Map.put(opts, key, Hashtag.normalize_name(value))
+
+        value when is_list(value) ->
+          normalized_value =
+            value
+            |> Enum.map(&Hashtag.normalize_name/1)
+            |> Enum.uniq()
+
+          Map.put(opts, key, normalized_value)
+
+        _ ->
+          opts
+      end
+    end)
+  end
+
   defp fetch_activities_query_ap_ids_ops(opts) do
     source_user = opts[:muting_user]
     ap_id_relationships = if source_user, do: [:mute, :reblog_mute], else: []
@@ -1121,6 +1251,8 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
   end
 
   def fetch_activities_query(recipients, opts \\ %{}) do
+    opts = normalize_fetch_activities_query_opts(opts)
+
     {restrict_blocked_opts, restrict_muted_opts, restrict_muted_reblogs_opts} =
       fetch_activities_query_ap_ids_ops(opts)
 
@@ -1128,50 +1260,51 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
       skip_thread_containment: Config.get([:instance, :skip_thread_containment])
     }
 
-    Activity
-    |> maybe_preload_objects(opts)
-    |> maybe_preload_bookmarks(opts)
-    |> maybe_preload_report_notes(opts)
-    |> maybe_set_thread_muted_field(opts)
-    |> maybe_order(opts)
-    |> restrict_recipients(recipients, opts[:user])
-    |> restrict_replies(opts)
-    |> restrict_tag(opts)
-    |> restrict_tag_reject(opts)
-    |> restrict_tag_all(opts)
-    |> restrict_since(opts)
-    |> restrict_local(opts)
-    |> restrict_remote(opts)
-    |> restrict_actor(opts)
-    |> restrict_type(opts)
-    |> restrict_state(opts)
-    |> restrict_favorited_by(opts)
-    |> restrict_blocked(restrict_blocked_opts)
-    |> restrict_muted(restrict_muted_opts)
-    |> restrict_filtered(opts)
-    |> restrict_media(opts)
-    |> restrict_visibility(opts)
-    |> restrict_thread_visibility(opts, config)
-    |> restrict_reblogs(opts)
-    |> restrict_pinned(opts)
-    |> restrict_muted_reblogs(restrict_muted_reblogs_opts)
-    |> restrict_instance(opts)
-    |> restrict_announce_object_actor(opts)
-    |> restrict_filtered(opts)
-    |> Activity.restrict_deactivated_users()
-    |> exclude_poll_votes(opts)
-    |> exclude_chat_messages(opts)
-    |> exclude_invisible_actors(opts)
-    |> exclude_visibility(opts)
-  end
-
-  def fetch_activities(recipients, opts \\ %{}, pagination \\ :keyset) do
-    list_memberships = Pleroma.List.memberships(opts[:user])
-
-    fetch_activities_query(recipients ++ list_memberships, opts)
-    |> Pagination.fetch_paginated(opts, pagination)
-    |> Enum.reverse()
-    |> maybe_update_cc(list_memberships, opts[:user])
+    query =
+      Activity
+      |> maybe_preload_objects(opts)
+      |> maybe_preload_bookmarks(opts)
+      |> maybe_preload_report_notes(opts)
+      |> maybe_set_thread_muted_field(opts)
+      |> maybe_order(opts)
+      |> restrict_recipients(recipients, opts[:user])
+      |> restrict_replies(opts)
+      |> restrict_since(opts)
+      |> restrict_local(opts)
+      |> restrict_remote(opts)
+      |> restrict_actor(opts)
+      |> restrict_type(opts)
+      |> restrict_state(opts)
+      |> restrict_favorited_by(opts)
+      |> restrict_blocked(restrict_blocked_opts)
+      |> restrict_muted(restrict_muted_opts)
+      |> restrict_filtered(opts)
+      |> restrict_media(opts)
+      |> restrict_visibility(opts)
+      |> restrict_thread_visibility(opts, config)
+      |> restrict_reblogs(opts)
+      |> restrict_pinned(opts)
+      |> restrict_muted_reblogs(restrict_muted_reblogs_opts)
+      |> restrict_instance(opts)
+      |> restrict_announce_object_actor(opts)
+      |> restrict_filtered(opts)
+      |> Activity.restrict_deactivated_users()
+      |> exclude_poll_votes(opts)
+      |> exclude_chat_messages(opts)
+      |> exclude_invisible_actors(opts)
+      |> exclude_visibility(opts)
+
+    if Config.feature_enabled?(:improved_hashtag_timeline) do
+      query
+      |> restrict_hashtag_any(opts)
+      |> restrict_hashtag_all(opts)
+      |> restrict_hashtag_reject_any(opts)
+    else
+      query
+      |> restrict_embedded_tag_any(opts)
+      |> restrict_embedded_tag_all(opts)
+      |> restrict_embedded_tag_reject_any(opts)
+    end
   end
 
   @doc """
diff --git a/lib/pleroma/web/activity_pub/mrf/simple_policy.ex b/lib/pleroma/web/activity_pub/mrf/simple_policy.ex
index bb3838d2c..0b1be8c51 100644
--- a/lib/pleroma/web/activity_pub/mrf/simple_policy.ex
+++ b/lib/pleroma/web/activity_pub/mrf/simple_policy.ex
@@ -74,9 +74,11 @@ defmodule Pleroma.Web.ActivityPub.MRF.SimplePolicy do
 
     object =
       if MRF.subdomain_match?(media_nsfw, actor_host) do
-        tags = (child_object["tag"] || []) ++ ["nsfw"]
-        child_object = Map.put(child_object, "tag", tags)
-        child_object = Map.put(child_object, "sensitive", true)
+        child_object =
+          child_object
+          |> Map.put("tag", (child_object["tag"] || []) ++ ["nsfw"])
+          |> Map.put("sensitive", true)
+
         Map.put(object, "object", child_object)
       else
         object
diff --git a/lib/pleroma/web/activity_pub/transmogrifier.ex b/lib/pleroma/web/activity_pub/transmogrifier.ex
index 4d9a5617e..0a701334f 100644
--- a/lib/pleroma/web/activity_pub/transmogrifier.ex
+++ b/lib/pleroma/web/activity_pub/transmogrifier.ex
@@ -32,18 +32,18 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
   """
   def fix_object(object, options \\ []) do
     object
-    |> strip_internal_fields
-    |> fix_actor
-    |> fix_url
-    |> fix_attachments
-    |> fix_context
+    |> strip_internal_fields()
+    |> fix_actor()
+    |> fix_url()
+    |> fix_attachments()
+    |> fix_context()
     |> fix_in_reply_to(options)
-    |> fix_emoji
-    |> fix_tag
-    |> set_sensitive
-    |> fix_content_map
-    |> fix_addressing
-    |> fix_summary
+    |> fix_emoji()
+    |> fix_tag()
+    |> set_sensitive()
+    |> fix_content_map()
+    |> fix_addressing()
+    |> fix_summary()
     |> fix_type(options)
   end
 
@@ -315,10 +315,9 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
     tags =
       tag
       |> Enum.filter(fn data -> data["type"] == "Hashtag" and data["name"] end)
-      |> Enum.map(fn %{"name" => name} ->
-        name
-        |> String.slice(1..-1)
-        |> String.downcase()
+      |> Enum.map(fn
+        %{"name" => "#" <> hashtag} -> String.downcase(hashtag)
+        %{"name" => hashtag} -> String.downcase(hashtag)
       end)
 
     Map.put(object, "tag", tag ++ tags)
diff --git a/lib/pleroma/web/feed/feed_view.ex b/lib/pleroma/web/feed/feed_view.ex
index df97d2f46..66940f311 100644
--- a/lib/pleroma/web/feed/feed_view.ex
+++ b/lib/pleroma/web/feed/feed_view.ex
@@ -32,6 +32,7 @@ defmodule Pleroma.Web.Feed.FeedView do
 
     %{
       activity: activity,
+      object: object,
       data: Map.get(object, :data),
       actor: actor
     }
diff --git a/lib/pleroma/web/mastodon_api/controllers/timeline_controller.ex b/lib/pleroma/web/mastodon_api/controllers/timeline_controller.ex
index cef299aa4..c611958be 100644
--- a/lib/pleroma/web/mastodon_api/controllers/timeline_controller.ex
+++ b/lib/pleroma/web/mastodon_api/controllers/timeline_controller.ex
@@ -133,34 +133,25 @@ defmodule Pleroma.Web.MastodonAPI.TimelineController do
   end
 
   defp hashtag_fetching(params, user, local_only) do
-    tags =
+    # Note: not sanitizing tag options at this stage (may be mix-cased, have duplicates etc.)
+    tags_any =
       [params[:tag], params[:any]]
       |> List.flatten()
-      |> Enum.uniq()
-      |> Enum.reject(&is_nil/1)
-      |> Enum.map(&String.downcase/1)
-
-    tag_all =
-      params
-      |> Map.get(:all, [])
-      |> Enum.map(&String.downcase/1)
-
-    tag_reject =
-      params
-      |> Map.get(:none, [])
-      |> Enum.map(&String.downcase/1)
-
-    _activities =
-      params
-      |> Map.put(:type, "Create")
-      |> Map.put(:local_only, local_only)
-      |> Map.put(:blocking_user, user)
-      |> Map.put(:muting_user, user)
-      |> Map.put(:user, user)
-      |> Map.put(:tag, tags)
-      |> Map.put(:tag_all, tag_all)
-      |> Map.put(:tag_reject, tag_reject)
-      |> ActivityPub.fetch_public_activities()
+      |> Enum.filter(& &1)
+
+    tag_all = Map.get(params, :all, [])
+    tag_reject = Map.get(params, :none, [])
+
+    params
+    |> Map.put(:type, "Create")
+    |> Map.put(:local_only, local_only)
+    |> Map.put(:blocking_user, user)
+    |> Map.put(:muting_user, user)
+    |> Map.put(:user, user)
+    |> Map.put(:tag, tags_any)
+    |> Map.put(:tag_all, tag_all)
+    |> Map.put(:tag_reject, tag_reject)
+    |> ActivityPub.fetch_public_activities()
   end
 
   # GET /api/v1/timelines/tag/:tag
diff --git a/lib/pleroma/web/mastodon_api/views/status_view.ex b/lib/pleroma/web/mastodon_api/views/status_view.ex
index f3f54e03d..d30c9fa68 100644
--- a/lib/pleroma/web/mastodon_api/views/status_view.ex
+++ b/lib/pleroma/web/mastodon_api/views/status_view.ex
@@ -198,8 +198,10 @@ defmodule Pleroma.Web.MastodonAPI.StatusView do
     like_count = object.data["like_count"] || 0
     announcement_count = object.data["announcement_count"] || 0
 
-    tags = object.data["tag"] || []
-    sensitive = object.data["sensitive"] || Enum.member?(tags, "nsfw")
+    hashtags = Object.hashtags(object)
+    sensitive = object.data["sensitive"] || Enum.member?(hashtags, "nsfw")
+
+    tags = Object.tags(object)
 
     tag_mentions =
       tags
diff --git a/lib/pleroma/web/templates/feed/feed/_activity.atom.eex b/lib/pleroma/web/templates/feed/feed/_activity.atom.eex
index 3fd150c4e..6688830ba 100644
--- a/lib/pleroma/web/templates/feed/feed/_activity.atom.eex
+++ b/lib/pleroma/web/templates/feed/feed/_activity.atom.eex
@@ -22,7 +22,7 @@
     <link type="text/html" href='<%= @data["external_url"] %>' rel="alternate"/>
   <% end %>
 
-  <%= for tag <- @data["tag"] || [] do %>
+  <%= for tag <- Pleroma.Object.hashtags(@object) do %>
     <category term="<%= tag %>"></category>
   <% end %>
 
diff --git a/lib/pleroma/web/templates/feed/feed/_activity.rss.eex b/lib/pleroma/web/templates/feed/feed/_activity.rss.eex
index 947bbb099..592b9dcdc 100644
--- a/lib/pleroma/web/templates/feed/feed/_activity.rss.eex
+++ b/lib/pleroma/web/templates/feed/feed/_activity.rss.eex
@@ -22,7 +22,7 @@
 
   <link rel="ostatus:conversation"><%= activity_context(@activity) %></link>
 
-  <%= for tag <- @data["tag"] || [] do %>
+  <%= for tag <- Pleroma.Object.hashtags(@object) do %>
     <category term="<%= tag %>"></category>
   <% end %>
 
diff --git a/lib/pleroma/web/templates/feed/feed/_tag_activity.atom.eex b/lib/pleroma/web/templates/feed/feed/_tag_activity.atom.eex
index cf5874a91..c2de28fe4 100644
--- a/lib/pleroma/web/templates/feed/feed/_tag_activity.atom.eex
+++ b/lib/pleroma/web/templates/feed/feed/_tag_activity.atom.eex
@@ -41,7 +41,7 @@
       <% end %>
     <% end %>
 
-    <%= for tag <- @data["tag"] || [] do %>
+    <%= for tag <- Pleroma.Object.hashtags(@object) do %>
       <category term="<%= tag %>"></category>
     <% end %>