diff --git a/apps/els_core/src/els_config.erl b/apps/els_core/src/els_config.erl
index 7c7facf5f..4007f3971 100644
--- a/apps/els_core/src/els_config.erl
+++ b/apps/els_core/src/els_config.erl
@@ -267,8 +267,8 @@ consult_config([Path | Paths], ReportMissingConfig) ->
       [Config] -> {Path, Config}
   catch
     Class:Error ->
-      ?LOG_WARNING( "Could not read config file: path=~p class=~p error=~p"
-                  , [Path, Class, Error]),
+      ?LOG_DEBUG( "Could not read config file: path=~p class=~p error=~p"
+                , [Path, Class, Error]),
       consult_config(Paths, ReportMissingConfig)
   end.
 
diff --git a/apps/els_core/src/els_utils.erl b/apps/els_core/src/els_utils.erl
index ded6b42b1..80b02013b 100644
--- a/apps/els_core/src/els_utils.erl
+++ b/apps/els_core/src/els_utils.erl
@@ -110,7 +110,7 @@ find_header(Id) ->
       {ok, Uri};
     [] ->
       FileName = atom_to_list(Id) ++ ".hrl",
-      els_indexing:find_and_index_file(FileName)
+      els_indexing:find_and_deeply_index_file(FileName)
   end.
 
 %% @doc Look for a module in the DB
@@ -128,14 +128,14 @@ find_module(Id) ->
 find_modules(Id) ->
   {ok, Candidates} = els_dt_document_index:lookup(Id),
   case [Uri || #{kind := module, uri := Uri} <- Candidates] of
-      [] ->
-          FileName = atom_to_list(Id) ++ ".erl",
-          case els_indexing:find_and_index_file(FileName) of
-              {ok, Uri} -> {ok, [Uri]};
-              Error -> Error
-          end;
-      Uris ->
-          {ok, prioritize_uris(Uris)}
+    [] ->
+      FileName = atom_to_list(Id) ++ ".erl",
+      case els_indexing:find_and_deeply_index_file(FileName) of
+        {ok, Uri} -> {ok, [Uri]};
+        Error -> Error
+      end;
+    Uris ->
+      {ok, prioritize_uris(Uris)}
   end.
 
 %% @doc Look for a document in the DB.
@@ -150,13 +150,13 @@ lookup_document(Uri) ->
       {ok, Document};
     {ok, []} ->
       Path = els_uri:path(Uri),
-      {ok, Uri} = els_indexing:index_file(Path),
+      {ok, Uri} = els_indexing:shallow_index(Path, app),
       case els_dt_document:lookup(Uri) of
         {ok, [Document]} ->
           {ok, Document};
-        Error ->
-          ?LOG_INFO("Document lookup failed [error=~p] [uri=~p]", [Error, Uri]),
-          {error, Error}
+        {ok, []} ->
+          ?LOG_INFO("Document lookup failed [uri=~p]", [Uri]),
+          {error, document_lookup_failed}
       end
   end.
 
diff --git a/apps/els_lsp/src/els_background_job.erl b/apps/els_lsp/src/els_background_job.erl
index d58b71908..a5687d8c3 100644
--- a/apps/els_lsp/src/els_background_job.erl
+++ b/apps/els_lsp/src/els_background_job.erl
@@ -187,13 +187,21 @@ terminate(normal, #{ config := #{on_complete := OnComplete}
   ?LOG_DEBUG("Background job completed.", []),
   OnComplete(InternalState),
   ok;
-terminate(Reason, #{ config := #{on_error := OnError}
+terminate(Reason, #{ config := #{ on_error := OnError
+                                , title := Title
+                                }
                    , internal_state := InternalState
                    , token := Token
                    , total := Total
                    , progress_enabled := ProgressEnabled
                    }) ->
-  ?LOG_WARNING( "Background job aborted. [reason=~p]", [Reason]),
+  case Reason of
+    shutdown ->
+      ?LOG_DEBUG("Background job terminated.", []);
+    _ ->
+      ?LOG_ERROR( "Background job aborted. [reason=~p] [title=~p",
+                  [Reason, Title])
+  end,
   notify_end(Token, Total, ProgressEnabled),
   OnError(InternalState),
   ok.
diff --git a/apps/els_lsp/src/els_buffer_server.erl b/apps/els_lsp/src/els_buffer_server.erl
new file mode 100644
index 000000000..293037323
--- /dev/null
+++ b/apps/els_lsp/src/els_buffer_server.erl
@@ -0,0 +1,126 @@
+%%%=============================================================================
+%%% @doc Buffer edits to an open buffer to avoid re-indexing too often.
+%%% @end
+%%%=============================================================================
+-module(els_buffer_server).
+
+%%==============================================================================
+%% API
+%%==============================================================================
+-export([ new/2
+        , stop/1
+        , apply_edits/2
+        , flush/1
+        ]).
+
+-export([ start_link/2 ]).
+
+%%==============================================================================
+%% Callbacks for the gen_server behaviour
+%%==============================================================================
+-behaviour(gen_server).
+-export([ init/1
+        , handle_call/3
+        , handle_cast/2
+        , handle_info/2
+        ]).
+
+%%==============================================================================
+%% Macro Definitions
+%%==============================================================================
+-define(FLUSH_DELAY, 200). %% ms
+
+%%==============================================================================
+%% Type Definitions
+%%==============================================================================
+-type text() :: binary().
+-type state() :: #{ uri := uri()
+                  , text := text()
+                  , ref := undefined | reference()
+                  , pending := [{pid(), any()}]
+                  }.
+-type buffer() :: pid().
+
+%%==============================================================================
+%% Includes
+%%==============================================================================
+-include_lib("kernel/include/logger.hrl").
+-include("els_lsp.hrl").
+
+%%==============================================================================
+%% API
+%%==============================================================================
+-spec new(uri(), text()) -> {ok, pid()}.
+new(Uri, Text) ->
+  supervisor:start_child(els_buffer_sup, [Uri, Text]).
+
+-spec stop(buffer()) -> ok.
+stop(Buffer) ->
+  supervisor:terminate_child(els_buffer_sup, Buffer).
+
+-spec apply_edits(buffer(), [els_text:edit()]) -> ok.
+apply_edits(Buffer, Edits) ->
+  gen_server:cast(Buffer, {apply_edits, Edits}).
+
+-spec flush(buffer()) -> text().
+flush(Buffer) ->
+  gen_server:call(Buffer, {flush}).
+
+-spec start_link(uri(), text()) -> {ok, buffer()}.
+start_link(Uri, Text) ->
+  gen_server:start_link(?MODULE, {Uri, Text}, []).
+
+%%==============================================================================
+%% Callbacks for the gen_server behaviour
+%%==============================================================================
+-spec init({uri(), text()}) -> {ok, state()}.
+init({Uri, Text}) ->
+  {ok, #{ uri => Uri, text => Text, ref => undefined, pending => [] }}.
+
+-spec handle_call(any(), {pid(), any()}, state()) -> {reply, any(), state()}.
+handle_call({flush}, From, State) ->
+  #{uri := Uri, ref := Ref0, pending := Pending0} = State,
+  ?LOG_DEBUG("[~p] Flushing request [uri=~p]", [?MODULE, Uri]),
+  cancel_flush(Ref0),
+  Ref = schedule_flush(),
+  {noreply, State#{ref => Ref, pending => [From|Pending0]}};
+handle_call(Request, _From, State) ->
+  {reply, {not_implemented, Request}, State}.
+
+-spec handle_cast(any(), state()) -> {noreply, state()}.
+handle_cast({apply_edits, Edits}, #{uri := Uri} = State) ->
+  ?LOG_DEBUG("[~p] Applying edits [uri=~p] [edits=~p]", [?MODULE, Uri, Edits]),
+  #{text := Text0, ref := Ref0} = State,
+  cancel_flush(Ref0),
+  Text = els_text:apply_edits(Text0, Edits),
+  Ref = schedule_flush(),
+  {noreply, State#{text => Text, ref => Ref}}.
+
+-spec handle_info(any(), state()) -> {noreply, state()}.
+handle_info(flush, #{uri := Uri, text := Text, pending := Pending0} = State) ->
+  ?LOG_DEBUG("[~p] Flushing [uri=~p]", [?MODULE, Uri]),
+  do_flush(Uri, Text),
+  [gen_server:reply(From, Text) || From <- Pending0],
+  {noreply, State#{pending => [], ref => undefined}};
+handle_info(_Request, State) ->
+  {noreply, State}.
+
+%%==============================================================================
+%% Internal Functions
+%%==============================================================================
+
+-spec schedule_flush() -> reference().
+schedule_flush() ->
+  erlang:send_after(?FLUSH_DELAY, self(), flush).
+
+-spec cancel_flush(undefined | reference()) -> ok.
+cancel_flush(undefined) ->
+  ok;
+cancel_flush(Ref) ->
+  erlang:cancel_timer(Ref),
+  ok.
+
+-spec do_flush(uri(), text()) -> ok.
+do_flush(Uri, Text) ->
+  {ok, Document} = els_utils:lookup_document(Uri),
+  els_indexing:deep_index(Document#{text => Text}).
diff --git a/apps/els_lsp/src/els_buffer_sup.erl b/apps/els_lsp/src/els_buffer_sup.erl
new file mode 100644
index 000000000..c122983ea
--- /dev/null
+++ b/apps/els_lsp/src/els_buffer_sup.erl
@@ -0,0 +1,47 @@
+%%==============================================================================
+%% Supervisor for Buffers
+%%==============================================================================
+-module(els_buffer_sup).
+
+%%==============================================================================
+%% Behaviours
+%%==============================================================================
+-behaviour(supervisor).
+
+%%==============================================================================
+%% Exports
+%%==============================================================================
+
+%% API
+-export([ start_link/0 ]).
+
+%% Supervisor Callbacks
+-export([ init/1 ]).
+
+%%==============================================================================
+%% Defines
+%%==============================================================================
+-define(SERVER, ?MODULE).
+
+%%==============================================================================
+%% API
+%%==============================================================================
+-spec start_link() -> {ok, pid()}.
+start_link() ->
+  supervisor:start_link({local, ?SERVER}, ?MODULE, []).
+
+%%==============================================================================
+%% Supervisor callbacks
+%%==============================================================================
+-spec init([]) -> {ok, {supervisor:sup_flags(), [supervisor:child_spec()]}}.
+init([]) ->
+  SupFlags = #{ strategy  => simple_one_for_one
+              , intensity => 5
+              , period    => 60
+              },
+  ChildSpecs = [#{ id       => els_buffer_sup
+                 , start    => {els_buffer_server, start_link, []}
+                 , restart  => temporary
+                 , shutdown => 5000
+                 }],
+  {ok, {SupFlags, ChildSpecs}}.
diff --git a/apps/els_lsp/src/els_completion_provider.erl b/apps/els_lsp/src/els_completion_provider.erl
index a8d5c2650..e8d8fec9b 100644
--- a/apps/els_lsp/src/els_completion_provider.erl
+++ b/apps/els_lsp/src/els_completion_provider.erl
@@ -44,8 +44,18 @@ handle_request({completion, Params}, State) ->
                             }
    , <<"textDocument">> := #{<<"uri">> := Uri}
    } = Params,
-  ok = els_index_buffer:flush(Uri),
-  {ok, #{text := Text} = Document} = els_utils:lookup_document(Uri),
+  %% Ensure there are no pending changes.
+  {ok, Document} = els_utils:lookup_document(Uri),
+  #{buffer := Buffer, text := Text0} = Document,
+  Text = case Buffer of
+           undefined ->
+             %% This clause is only kept due to the current test suites,
+             %% where LSP clients can trigger a completion request
+             %% before a did_open
+             Text0;
+           _ ->
+             els_buffer_server:flush(Buffer)
+         end,
   Context = maps:get( <<"context">>
                     , Params
                     , #{ <<"triggerKind">> => ?COMPLETION_TRIGGER_KIND_INVOKED }
diff --git a/apps/els_lsp/src/els_dt_document.erl b/apps/els_lsp/src/els_dt_document.erl
index 6cc4e0376..1c37386ca 100644
--- a/apps/els_lsp/src/els_dt_document.erl
+++ b/apps/els_lsp/src/els_dt_document.erl
@@ -22,7 +22,7 @@
         , delete/1
         ]).
 
--export([ new/2
+-export([ new/3
         , pois/1
         , pois/2
         , get_element_at_pos/3
@@ -31,29 +31,37 @@
         , applications_at_pos/3
         , wrapping_functions/2
         , wrapping_functions/3
+        , find_candidates/1
         ]).
 
 %%==============================================================================
 %% Includes
 %%==============================================================================
 -include("els_lsp.hrl").
+-include_lib("kernel/include/logger.hrl").
 
 %%==============================================================================
 %% Type Definitions
 %%==============================================================================
 -type id()   :: atom().
 -type kind() :: module | header | other.
+-type source() :: otp | app | dep.
+-type buffer() :: pid().
+-export_type([source/0]).
 
 %%==============================================================================
 %% Item Definition
 %%==============================================================================
 
--record(els_dt_document, { uri  :: uri()    | '_'
+-record(els_dt_document, { uri  :: uri()    | '_' | '$1'
                          , id   :: id()     | '_'
                          , kind :: kind()   | '_'
                          , text :: binary() | '_'
                          , md5  :: binary() | '_'
-                         , pois :: [poi()]  | '_'
+                         , pois :: [poi()]  | '_' | ondemand
+                         , source :: source() | '$2'
+                         , buffer :: buffer() | '_' | undefined
+                         , words :: sets:set() | '_' | '$3'
                          }).
 -type els_dt_document() :: #els_dt_document{}.
 
@@ -62,7 +70,10 @@
                  , kind := kind()
                  , text := binary()
                  , md5  => binary()
-                 , pois => [poi()]
+                 , pois => [poi()] | ondemand
+                 , source => source()
+                 , buffer => buffer() | undefined
+                 , words => sets:set()
                  }.
 -export_type([ id/0
              , item/0
@@ -91,6 +102,9 @@ from_item(#{ uri  := Uri
            , text := Text
            , md5  := MD5
            , pois := POIs
+           , source := Source
+           , buffer := Buffer
+           , words := Words
            }) ->
   #els_dt_document{ uri  = Uri
                   , id   = Id
@@ -98,6 +112,9 @@ from_item(#{ uri  := Uri
                   , text = Text
                   , md5  = MD5
                   , pois = POIs
+                  , source = Source
+                  , buffer = Buffer
+                  , words = Words
                   }.
 
 -spec to_item(els_dt_document()) -> item().
@@ -107,6 +124,9 @@ to_item(#els_dt_document{ uri  = Uri
                         , text = Text
                         , md5  = MD5
                         , pois = POIs
+                        , source = Source
+                        , buffer = Buffer
+                        , words = Words
                         }) ->
   #{ uri  => Uri
    , id   => Id
@@ -114,6 +134,9 @@ to_item(#els_dt_document{ uri  = Uri
    , text => Text
    , md5  => MD5
    , pois => POIs
+   , source => Source
+   , buffer => Buffer
+   , words => Words
    }.
 
 -spec insert(item()) -> ok | {error, any()}.
@@ -130,33 +153,39 @@ lookup(Uri) ->
 delete(Uri) ->
   els_db:delete(name(), Uri).
 
--spec new(uri(), binary()) -> item().
-new(Uri, Text) ->
+-spec new(uri(), binary(), source()) -> item().
+new(Uri, Text, Source) ->
   Extension = filename:extension(Uri),
   Id = binary_to_atom(filename:basename(Uri, Extension), utf8),
   case Extension of
     <<".erl">> ->
-      new(Uri, Text, Id, module);
+      new(Uri, Text, Id, module, Source);
     <<".hrl">> ->
-      new(Uri, Text, Id, header);
+      new(Uri, Text, Id, header, Source);
     _  ->
-      new(Uri, Text, Id, other)
+      new(Uri, Text, Id, other, Source)
   end.
 
--spec new(uri(), binary(), atom(), kind()) -> item().
-new(Uri, Text, Id, Kind) ->
-  {ok, POIs} = els_parser:parse(Text),
-  MD5        = erlang:md5(Text),
+-spec new(uri(), binary(), atom(), kind(), source()) -> item().
+new(Uri, Text, Id, Kind, Source) ->
+  MD5 = erlang:md5(Text),
   #{ uri  => Uri
    , id   => Id
    , kind => Kind
    , text => Text
    , md5  => MD5
-   , pois => POIs
+   , pois => ondemand
+   , source => Source
+   , buffer => undefined
+   , words => get_words(Text)
    }.
 
 %% @doc Returns the list of POIs for the current document
 -spec pois(item()) -> [poi()].
+pois(#{ uri := Uri, pois := ondemand }) ->
+  els_indexing:ensure_deeply_indexed(Uri),
+  {ok, #{pois := POIs}} = els_utils:lookup_document(Uri),
+  POIs;
 pois(#{ pois := POIs }) ->
   POIs.
 
@@ -201,3 +230,49 @@ wrapping_functions(Document, Line, Column) ->
 wrapping_functions(Document, Range) ->
   #{start := #{character := Character, line := Line}} = Range,
   wrapping_functions(Document, Line, Character).
+
+-spec find_candidates(atom() | string()) -> [uri()].
+find_candidates(Pattern) ->
+  %% ets:fun2ms(fun(#els_dt_document{source = Source, uri = Uri, words = Words})
+  %% when Source =/= otp -> {Uri, Words} end).
+  MS = [{#els_dt_document{ uri = '$1'
+                         , id = '_'
+                         , kind = '_'
+                         , text = '_'
+                         , md5 = '_'
+                         , pois = '_'
+                         , source = '$2'
+                         , buffer = '_'
+                         , words = '$3'},
+         [{'=/=', '$2', otp}],
+         [{{'$1', '$3'}}]}],
+  All = ets:select(name(), MS),
+  Fun = fun({Uri, Words}) ->
+            case sets:is_element(Pattern, Words) of
+              true -> {true, Uri};
+              false -> false
+            end
+        end,
+  lists:filtermap(Fun, All).
+
+-spec get_words(binary()) -> sets:set().
+get_words(Text) ->
+  case erl_scan:string(els_utils:to_list(Text)) of
+    {ok, Tokens, _EndLocation} ->
+      Fun = fun({atom, _Location, Atom}, Words) ->
+                sets:add_element(Atom, Words);
+               ({string, _Location, String}, Words) ->
+                case filename:extension(String) of
+                  ".hrl" ->
+                    Id = filename:rootname(filename:basename(String)),
+                    sets:add_element(Id, Words);
+                  _ ->
+                    Words
+                end;
+               (_, Words) ->
+                Words
+            end,
+      lists:foldl(Fun, sets:new(), Tokens);
+    {error, ErrorInfo, _ErrorLocation} ->
+      ?LOG_DEBUG("Errors while get_words ~p", [ErrorInfo])
+  end.
diff --git a/apps/els_lsp/src/els_dt_references.erl b/apps/els_lsp/src/els_dt_references.erl
index 0926f1790..52bd98882 100644
--- a/apps/els_lsp/src/els_dt_references.erl
+++ b/apps/els_lsp/src/els_dt_references.erl
@@ -18,7 +18,6 @@
 %%==============================================================================
 
 -export([ delete_by_uri/1
-        , find_all/0
         , find_by/1
         , find_by_id/2
         , insert/2
@@ -45,6 +44,15 @@
                  }.
 -export_type([ item/0 ]).
 
+-type poi_category() :: function
+                      | type
+                      | macro
+                      | record
+                      | include
+                      | include_lib
+                      | behaviour.
+-export_type([ poi_category/0 ]).
+
 %%==============================================================================
 %% Callbacks for the els_db_table Behaviour
 %%==============================================================================
@@ -82,12 +90,6 @@ insert(Kind, Map) when is_map(Map) ->
   Record = from_item(Kind, Map),
   els_db:write(name(), Record).
 
-%% @doc Find all
--spec find_all() -> {ok, [item()]} | {error, any()}.
-find_all() ->
-  Pattern = #els_dt_references{_ = '_'},
-  find_by(Pattern).
-
 %% @doc Find by id
 -spec find_by_id(poi_kind(), any()) -> {ok, [item()]} | {error, any()}.
 find_by_id(Kind, Id) ->
@@ -96,11 +98,13 @@ find_by_id(Kind, Id) ->
   find_by(Pattern).
 
 -spec find_by(tuple()) -> {ok, [item()]}.
-find_by(Pattern) ->
+find_by(#els_dt_references{id = Id} = Pattern) ->
+  Uris = els_text_search:find_candidate_uris(Id),
+  [els_indexing:ensure_deeply_indexed(Uri) || Uri <- Uris],
   {ok, Items} = els_db:match(name(), Pattern),
   {ok, [to_item(Item) || Item <- Items]}.
 
--spec kind_to_category(poi_kind()) -> function | type | macro | record.
+-spec kind_to_category(poi_kind()) -> poi_category().
 kind_to_category(Kind) when Kind =:= application;
                             Kind =:= export_entry;
                             Kind =:= function;
diff --git a/apps/els_lsp/src/els_dt_signatures.erl b/apps/els_lsp/src/els_dt_signatures.erl
index f2a2b8694..1a5b20318 100644
--- a/apps/els_lsp/src/els_dt_signatures.erl
+++ b/apps/els_lsp/src/els_dt_signatures.erl
@@ -19,13 +19,14 @@
 
 -export([ insert/1
         , lookup/1
-        , delete_by_module/1
+        , delete_by_uri/1
         ]).
 
 %%==============================================================================
 %% Includes
 %%==============================================================================
 -include("els_lsp.hrl").
+-include_lib("kernel/include/logger.hrl").
 
 %%==============================================================================
 %% Item Definition
@@ -72,11 +73,18 @@ insert(Map) when is_map(Map) ->
   els_db:write(name(), Record).
 
 -spec lookup(mfa()) -> {ok, [item()]}.
-lookup(MFA) ->
+lookup({M, _F, _A} = MFA) ->
+  {ok, _Uris} = els_utils:find_modules(M),
   {ok, Items} = els_db:lookup(name(), MFA),
   {ok, [to_item(Item) || Item <- Items]}.
 
--spec delete_by_module(atom()) -> ok.
-delete_by_module(Module) ->
-  Pattern = #els_dt_signatures{mfa = {Module, '_', '_'}, _ = '_'},
-  ok = els_db:match_delete(name(), Pattern).
+-spec delete_by_uri(uri()) -> ok.
+delete_by_uri(Uri) ->
+  case filename:extension(Uri) of
+    <<".erl">> ->
+      Module = els_uri:module(Uri),
+      Pattern = #els_dt_signatures{mfa = {Module, '_', '_'}, _ = '_'},
+      ok = els_db:match_delete(name(), Pattern);
+    _ ->
+      ok
+  end.
diff --git a/apps/els_lsp/src/els_index_buffer.erl b/apps/els_lsp/src/els_index_buffer.erl
deleted file mode 100644
index 7687cb12d..000000000
--- a/apps/els_lsp/src/els_index_buffer.erl
+++ /dev/null
@@ -1,140 +0,0 @@
-%% @doc Buffer textedits to avoid spamming indexing for every keystroke
-%%
-%% FIXME: Currently implemented as a simple process.
-%%        Might be nicer to rewrite this as a gen_server
-%% FIXME: Edits are bottlenecked by this single process, so this could slow
-%%        down indexing when making changes in multiple files, this could be
-%%        mitigated by using a worker pool or spawning a process per Uri.
--module(els_index_buffer).
-
--export([ start/0
-        , stop/0
-        , apply_edits_async/2
-        , flush/1
-        , load/2
-        ]).
-
--include_lib("kernel/include/logger.hrl").
--include("els_lsp.hrl").
-
--define(SERVER, ?MODULE).
-
--spec start() -> {ok, pid()} | {error, _}.
-start() ->
-  case whereis(?SERVER) of
-    undefined ->
-      Pid = proc_lib:spawn_link(fun loop/0),
-      true = erlang:register(?SERVER, Pid),
-      ?LOG_INFO("[~p] Started.", [?SERVER]),
-      {ok, Pid};
-    Pid ->
-      {error, {already_started, Pid}}
-  end.
-
--spec stop() -> ok.
-stop() ->
-  ?SERVER ! stop,
-  erlang:unregister(?SERVER),
-  ?LOG_INFO("[~p] Stopped.", [?SERVER]),
-  ok.
-
--spec apply_edits_async(uri(), [els_text:edit()]) -> ok.
-apply_edits_async(Uri, Edits) ->
-  ?SERVER ! {apply_edits, Uri, Edits},
-  ok.
-
--spec load(uri(), binary()) -> ok.
-load(Uri, Text) ->
-  Ref = make_ref(),
-  ?SERVER ! {load, self(), Ref, Uri, Text},
-  receive
-    {Ref, done} ->
-      ok
-  end.
-
--spec flush(uri()) -> ok.
-flush(Uri) ->
-  Ref = make_ref(),
-  ?SERVER ! {flush, self(), Ref, Uri},
-  receive
-    {Ref, done} ->
-      ok
-  end.
-
--spec loop() -> ok.
-loop() ->
-  receive
-    stop -> ok;
-    {apply_edits, Uri, Edits} ->
-      try
-        do_apply_edits(Uri, Edits)
-      catch E:R:St ->
-          ?LOG_ERROR("[~p] Crashed while applying edits ~p: ~p",
-                     [?SERVER, Uri, {E, R, St}])
-      end,
-      loop();
-    {flush, Pid, Ref, Uri} ->
-      try
-        do_flush(Uri)
-      catch E:R:St ->
-          ?LOG_ERROR("[~p] Crashed while flushing ~p: ~p",
-                     [?SERVER, Uri, {E, R, St}])
-      end,
-      Pid ! {Ref, done},
-      loop();
-    {load, Pid, Ref, Uri, Text} ->
-      try
-        do_load(Uri, Text)
-      catch E:R:St ->
-          ?LOG_ERROR("[~p] Crashed while loading ~p: ~p",
-                     [?SERVER, Uri, {E, R, St}])
-      end,
-      Pid ! {Ref, done},
-      loop()
-  end.
-
--spec do_apply_edits(uri(), [els_text:edit()]) -> ok.
-do_apply_edits(Uri, Edits0) ->
-  ?LOG_DEBUG("[~p] Processing index request for ~p", [?SERVER, Uri]),
-  {ok, [#{text := Text0}]} = els_dt_document:lookup(Uri),
-  ?LOG_DEBUG("[~p] Apply edits: ~p", [?SERVER, Edits0]),
-  Text1 = els_text:apply_edits(Text0, Edits0),
-  Text = receive_all(Uri, Text1),
-  ?LOG_DEBUG("[~p] Started indexing ~p", [?SERVER, Uri]),
-  {Duration, ok} = timer:tc(fun() -> els_indexing:index(Uri, Text, 'deep') end),
-  ?LOG_DEBUG("[~p] Done indexing ~p [duration: ~pms]",
-             [?SERVER, Uri, Duration div 1000]),
-  ok.
-
--spec do_flush(uri()) -> ok.
-do_flush(Uri) ->
-  ?LOG_DEBUG("[~p] Flushing ~p", [?SERVER, Uri]),
-  {ok, [#{text := Text0}]} = els_dt_document:lookup(Uri),
-  Text = receive_all(Uri, Text0),
-  {Duration, ok} = timer:tc(fun() -> els_indexing:index(Uri, Text, 'deep') end),
-  ?LOG_DEBUG("[~p] Done flushing ~p [duration: ~pms]",
-             [?SERVER, Uri, Duration div 1000]),
-  ok.
-
--spec do_load(uri(), binary()) -> ok.
-do_load(Uri, Text) ->
-  ?LOG_DEBUG("[~p] Loading ~p", [?SERVER, Uri]),
-  {Duration, ok} =
-    timer:tc(fun() ->
-                 els_indexing:index(Uri, Text, 'deep')
-             end),
-  ?LOG_DEBUG("[~p] Done load ~p [duration: ~pms]",
-             [?SERVER, Uri, Duration div 1000]),
-  ok.
-
--spec receive_all(uri(), binary()) -> binary().
-receive_all(Uri, Text0) ->
-  receive
-    {apply_edits, Uri, Edits} ->
-      ?LOG_DEBUG("[~p] Received more edits ~p.", [?SERVER, Uri]),
-      ?LOG_DEBUG("[~p] Apply edits: ~p", [?SERVER, Edits]),
-      Text = els_text:apply_edits(Text0, Edits),
-      receive_all(Uri, Text)
-  after
-    0 -> Text0
-  end.
diff --git a/apps/els_lsp/src/els_indexing.erl b/apps/els_lsp/src/els_indexing.erl
index f103698d6..dd300ef8a 100644
--- a/apps/els_lsp/src/els_indexing.erl
+++ b/apps/els_lsp/src/els_indexing.erl
@@ -3,12 +3,14 @@
 -callback index(els_dt_document:item()) -> ok.
 
 %% API
--export([ find_and_index_file/1
-        , index_file/1
-        , index/3
+-export([ find_and_deeply_index_file/1
         , index_dir/2
         , start/0
         , maybe_start/0
+        , ensure_deeply_indexed/1
+        , shallow_index/2
+        , deep_index/1
+        , remove/1
         ]).
 
 %%==============================================================================
@@ -20,48 +22,30 @@
 %%==============================================================================
 %% Types
 %%==============================================================================
--type mode()  :: 'deep' | 'shallow'.
 
 %%==============================================================================
 %% Exported functions
 %%==============================================================================
 
--spec find_and_index_file(string()) ->
+-spec find_and_deeply_index_file(string()) ->
    {ok, uri()} | {error, any()}.
-find_and_index_file(FileName) ->
+find_and_deeply_index_file(FileName) ->
   SearchPaths = els_config:get(search_paths),
   case file:path_open( SearchPaths
                      , els_utils:to_binary(FileName)
                      , [read]
                      )
   of
-    {ok, IoDevice, FullName} ->
+    {ok, IoDevice, Path} ->
       %% TODO: Avoid opening file twice
       file:close(IoDevice),
-      index_file(FullName);
+      Uri = els_uri:uri(Path),
+      ensure_deeply_indexed(Uri),
+      {ok, Uri};
     {error, Error} ->
       {error, Error}
   end.
 
--spec index_file(binary()) -> {ok, uri()}.
-index_file(Path) ->
-  GeneratedFilesTag = els_config_indexing:get_generated_files_tag(),
-  try_index_file(Path, 'deep', false, GeneratedFilesTag),
-  {ok, els_uri:uri(Path)}.
-
--spec index_if_not_generated(uri(), binary(), mode(), boolean(), string()) ->
-        ok | skipped.
-index_if_not_generated(Uri, Text, Mode, false, _GeneratedFilesTag) ->
-  index(Uri, Text, Mode);
-index_if_not_generated(Uri, Text, Mode, true, GeneratedFilesTag) ->
-  case is_generated_file(Text, GeneratedFilesTag) of
-    true ->
-      ?LOG_DEBUG("Skip indexing for generated file ~p", [Uri]),
-      skipped;
-    false ->
-      ok = index(Uri, Text, Mode)
-  end.
-
 -spec is_generated_file(binary(), string()) -> boolean().
 is_generated_file(Text, Tag) ->
   [Line|_] = string:split(Text, "\n", leading),
@@ -72,66 +56,84 @@ is_generated_file(Text, Tag) ->
       false
   end.
 
--spec index(uri(), binary(), mode()) -> ok.
-index(Uri, Text, Mode) ->
-  MD5 = erlang:md5(Text),
-  case els_dt_document:lookup(Uri) of
-    {ok, [#{md5 := MD5}]} ->
-      ok;
-    {ok, LookupResult} ->
-      Document = els_dt_document:new(Uri, Text),
-      do_index(Document, Mode, LookupResult =/= [])
+-spec ensure_deeply_indexed(uri()) -> ok.
+ensure_deeply_indexed(Uri) ->
+  {ok, #{pois := POIs} = Document} = els_utils:lookup_document(Uri),
+  case POIs of
+    ondemand ->
+      deep_index(Document);
+    _ ->
+      ok
   end.
 
--spec do_index(els_dt_document:item(), mode(), boolean()) -> ok.
-do_index(#{uri := Uri, id := Id, kind := Kind} = Document, Mode, Reset) ->
-  case Mode of
-    'deep' ->
-      ok = els_dt_document:insert(Document);
-    'shallow' ->
-      %% Don't store detailed POIs when "shallow" indexing.
-      %% They will be reloaded and inserted when needed
-      %% by calling els_utils:lookup_document/1
-      ok
-  end,
-  %% Mapping from document id to uri
-  ModuleItem = els_dt_document_index:new(Id, Uri, Kind),
-  ok = els_dt_document_index:insert(ModuleItem),
-  index_signatures(Document),
-  index_references(Document, Mode, Reset).
+-spec deep_index(els_dt_document:item()) -> ok.
+deep_index(Document) ->
+  #{id := Id, uri := Uri, text := Text, source := Source} = Document,
+  {ok, POIs} = els_parser:parse(Text),
+  ok = els_dt_document:insert(Document#{pois => POIs}),
+  index_signatures(Id, Uri, Text, POIs),
+  case Source of
+    otp ->
+      ok;
+    S when S =:= app orelse S =:= dep ->
+      index_references(Id, Uri, POIs)
+  end.
 
--spec index_signatures(els_dt_document:item()) -> ok.
-index_signatures(#{id := Id, text := Text} = Document) ->
-  Specs  = els_dt_document:pois(Document, [spec]),
-  [ begin
-      #{from := From, to := To} = Range,
-      Spec = els_text:range(Text, From, To),
-      els_dt_signatures:insert(#{ mfa => {Id, F, A} , spec => Spec})
-    end
-    || #{id := {F, A}, range := Range} <- Specs
-  ],
+-spec index_signatures(atom(), uri(), binary(), [poi()]) -> ok.
+index_signatures(Id, Uri, Text, POIs) ->
+  ok = els_dt_signatures:delete_by_uri(Uri),
+  [index_signature(Id, Text, POI) || #{kind := spec} = POI <- POIs],
   ok.
 
--spec index_references(els_dt_document:item(), mode(), boolean()) -> ok.
-index_references(#{uri := Uri} = Document, 'deep', true) ->
-  %% Optimization to only do (non-optimized) match_delete when necessary
-  ok = els_dt_references:delete_by_uri(Uri),
-  index_references(Document, 'deep', false);
-index_references(#{uri := Uri} = Document, 'deep', false) ->
-  %% References
-  POIs  = els_dt_document:pois(Document, [ application
-                                         , behaviour
-                                         , implicit_fun
-                                         , include
-                                         , include_lib
-                                         , type_application
-                                         , import_entry
-                                         ]),
-  [register_reference(Uri, POI) || POI <- POIs],
+-spec index_signature(atom(), binary(), poi()) -> ok.
+index_signature(_M, _Text, #{id := undefined}) ->
   ok;
-index_references(_Document, 'shallow', _) ->
+index_signature(M, Text,   #{id := {F, A}, range := Range}) ->
+  #{from := From, to := To} = Range,
+  Spec = els_text:range(Text, From, To),
+  els_dt_signatures:insert(#{ mfa => {M, F, A}, spec => Spec}).
+
+-spec index_references(atom(), uri(), [poi()]) -> ok.
+index_references(Id, Uri, POIs) ->
+  ok = els_dt_references:delete_by_uri(Uri),
+  ReferenceKinds = [ %% Function
+                     application
+                   , implicit_fun
+                   , import_entry
+                     %% Include
+                   , include
+                   , include_lib
+                     %% Behaviour
+                   , behaviour
+                     %% Type
+                   , type_application
+                   ],
+  [index_reference(Id, Uri, POI)
+   || #{kind := Kind} = POI <- POIs,
+      lists:member(Kind, ReferenceKinds)],
   ok.
 
+-spec index_reference(atom(), uri(), poi()) -> ok.
+index_reference(M, Uri, #{id := {F, A}} = POI) ->
+  index_reference(M, Uri, POI#{id => {M, F, A}});
+index_reference(_M, Uri, #{kind := Kind, id := Id, range := Range}) ->
+  els_dt_references:insert(Kind, #{id => Id, uri => Uri, range => Range}).
+
+-spec shallow_index(binary(), els_dt_document:source()) -> {ok, uri()}.
+shallow_index(Path, Source) ->
+  Uri = els_uri:uri(Path),
+  {ok, Text} = file:read_file(Path),
+  shallow_index(Uri, Text, Source),
+  {ok, Uri}.
+
+-spec shallow_index(uri(), binary(), els_dt_document:source()) -> ok.
+shallow_index(Uri, Text, Source) ->
+  Document = els_dt_document:new(Uri, Text, Source),
+  ok = els_dt_document:insert(Document),
+  #{id := Id, kind := Kind} = Document,
+  ModuleItem = els_dt_document_index:new(Id, Uri, Kind),
+  ok = els_dt_document_index:insert(ModuleItem).
+
 -spec maybe_start() -> true | false.
 maybe_start() ->
   IndexingEnabled = els_config:get(indexing_enabled),
@@ -145,17 +147,18 @@ maybe_start() ->
 
 -spec start() -> ok.
 start() ->
-  start(<<"OTP">>, entries_otp()),
-  start(<<"Applications">>, entries_apps()),
-  start(<<"Dependencies">>, entries_deps()).
-
--spec start(binary(), [{string(), 'deep' | 'shallow'}]) -> ok.
-start(Group, Entries) ->
-  SkipGeneratedFiles = els_config_indexing:get_skip_generated_files(),
-  GeneratedFilesTag = els_config_indexing:get_generated_files_tag(),
-  Task = fun({Dir, Mode}, {Succeeded0, Skipped0, Failed0}) ->
-             {Su, Sk, Fa} = index_dir(Dir, Mode,
-                                      SkipGeneratedFiles, GeneratedFilesTag),
+  Skip = els_config_indexing:get_skip_generated_files(),
+  SkipTag = els_config_indexing:get_generated_files_tag(),
+  ?LOG_INFO("Start indexing. [skip=~p] [skip_tag=~p]", [Skip, SkipTag]),
+  start(<<"OTP">>, Skip, SkipTag, els_config:get(otp_paths), otp),
+  start(<<"Applications">>, Skip, SkipTag, els_config:get(apps_paths), app),
+  start(<<"Dependencies">>, Skip, SkipTag, els_config:get(deps_paths), dep).
+
+-spec start(binary(), boolean(), string(), [string()],
+            els_dt_document:source()) -> ok.
+start(Group, Skip, SkipTag, Entries, Source) ->
+  Task = fun(Dir, {Succeeded0, Skipped0, Failed0}) ->
+             {Su, Sk, Fa} = index_dir(Dir, Skip, SkipTag, Source),
              {Succeeded0 + Su, Skipped0 + Sk, Failed0 + Fa}
          end,
   Config = #{ task => Task
@@ -172,65 +175,48 @@ start(Group, Entries) ->
   {ok, _Pid} = els_background_job:new(Config),
   ok.
 
+-spec remove(uri()) -> ok.
+remove(Uri) ->
+  ok = els_dt_document:delete(Uri),
+  ok = els_dt_document_index:delete_by_uri(Uri),
+  ok = els_dt_references:delete_by_uri(Uri),
+  ok = els_dt_signatures:delete_by_uri(Uri).
+
 %%==============================================================================
 %% Internal functions
 %%==============================================================================
 
-
-%% @doc Try indexing a file.
--spec try_index_file(binary(), mode(), boolean(), string()) ->
-        ok | skipped | {error, any()}.
-try_index_file(FullName, Mode, SkipGeneratedFiles, GeneratedFilesTag) ->
+-spec shallow_index(binary(), boolean(), string(), els_dt_document:source()) ->
+        ok | skipped.
+shallow_index(FullName, SkipGeneratedFiles, GeneratedFilesTag, Source) ->
   Uri = els_uri:uri(FullName),
-  try
-    ?LOG_DEBUG("Indexing file. [filename=~s, uri=~s]", [FullName, Uri]),
-    {ok, Text} = file:read_file(FullName),
-    index_if_not_generated(Uri, Text, Mode,
-                           SkipGeneratedFiles, GeneratedFilesTag)
-  catch Type:Reason:St ->
-      ?LOG_ERROR("Error indexing file "
-                 "[filename=~s, uri=~s] "
-                 "~p:~p:~p", [FullName, Uri, Type, Reason, St]),
-      {error, {Type, Reason}}
+  ?LOG_DEBUG("Shallow indexing file. [filename=~s] [uri=~s]",
+             [FullName, Uri]),
+  {ok, Text} = file:read_file(FullName),
+  case SkipGeneratedFiles andalso is_generated_file(Text, GeneratedFilesTag) of
+    true ->
+      ?LOG_DEBUG("Skip indexing for generated file ~p", [Uri]),
+      skipped;
+    false ->
+      shallow_index(Uri, Text, Source)
   end.
 
--spec register_reference(uri(), poi()) -> ok.
-register_reference(Uri, #{id := {F, A}} = POI) ->
-  M = els_uri:module(Uri),
-  register_reference(Uri, POI#{id => {M, F, A}});
-register_reference(Uri, #{kind := Kind, id := Id, range := Range})
-  when %% Include
-       Kind =:= include;
-       Kind =:= include_lib;
-       %% Function
-       Kind =:= application;
-       Kind =:= implicit_fun;
-       Kind =:= import_entry;
-       %% Type
-       Kind =:= type_application;
-       %% Behaviour
-       Kind =:= behaviour ->
-  els_dt_references:insert( Kind
-                          , #{id => Id, uri => Uri, range => Range}
-                          ).
-
--spec index_dir(string(), mode()) ->
+-spec index_dir(string(), els_dt_document:source()) ->
         {non_neg_integer(), non_neg_integer(), non_neg_integer()}.
-index_dir(Dir, Mode) ->
-  SkipGeneratedFiles = els_config_indexing:get_skip_generated_files(),
-  GeneratedFilesTag = els_config_indexing:get_generated_files_tag(),
-  index_dir(Dir, Mode, SkipGeneratedFiles, GeneratedFilesTag).
+index_dir(Dir, Source) ->
+  Skip = els_config_indexing:get_skip_generated_files(),
+  SkipTag = els_config_indexing:get_generated_files_tag(),
+  index_dir(Dir, Skip, SkipTag, Source).
 
--spec index_dir(string(), mode(), boolean(), string()) ->
+-spec index_dir(string(), boolean(), string(), els_dt_document:source()) ->
         {non_neg_integer(), non_neg_integer(), non_neg_integer()}.
-index_dir(Dir, Mode, SkipGeneratedFiles, GeneratedFilesTag) ->
-  ?LOG_DEBUG("Indexing directory. [dir=~s] [mode=~s]", [Dir, Mode]),
+index_dir(Dir, Skip, SkipTag, Source) ->
+  ?LOG_DEBUG("Indexing directory. [dir=~s]", [Dir]),
   F = fun(FileName, {Succeeded, Skipped, Failed}) ->
-          case try_index_file(els_utils:to_binary(FileName), Mode,
-                              SkipGeneratedFiles, GeneratedFilesTag) of
+          BinaryName = els_utils:to_binary(FileName),
+          case shallow_index(BinaryName, Skip, SkipTag, Source) of
             ok -> {Succeeded + 1, Skipped, Failed};
-            skipped -> {Succeeded, Skipped + 1, Failed};
-            {error, _Error} -> {Succeeded, Skipped, Failed + 1}
+            skipped -> {Succeeded, Skipped + 1, Failed}
           end
       end,
   Filter = fun(Path) ->
@@ -246,19 +232,7 @@ index_dir(Dir, Mode, SkipGeneratedFiles, GeneratedFilesTag) ->
                                                    , {0, 0, 0}
                                                    ]
                                                  ),
-  ?LOG_DEBUG("Finished indexing directory. [dir=~s] [mode=~s] [time=~p] "
+  ?LOG_DEBUG("Finished indexing directory. [dir=~s] [time=~p] "
              "[succeeded=~p] [skipped=~p] [failed=~p]",
-             [Dir, Mode, Time/1000/1000, Succeeded, Skipped, Failed]),
+             [Dir, Time/1000/1000, Succeeded, Skipped, Failed]),
   {Succeeded, Skipped, Failed}.
-
--spec entries_apps() -> [{string(), 'deep' | 'shallow'}].
-entries_apps() ->
-  [{Dir, 'deep'} || Dir <- els_config:get(apps_paths)].
-
--spec entries_deps() -> [{string(), 'deep' | 'shallow'}].
-entries_deps() ->
-  [{Dir, 'deep'} || Dir <- els_config:get(deps_paths)].
-
--spec entries_otp() -> [{string(), 'deep' | 'shallow'}].
-entries_otp() ->
-  [{Dir, 'shallow'} || Dir <- els_config:get(otp_paths)].
diff --git a/apps/els_lsp/src/els_sup.erl b/apps/els_lsp/src/els_sup.erl
index 1a6d9efda..8fbe5bec2 100644
--- a/apps/els_lsp/src/els_sup.erl
+++ b/apps/els_lsp/src/els_sup.erl
@@ -67,14 +67,14 @@ init([]) ->
                   , start => {els_distribution_sup, start_link, []}
                   , type  => supervisor
                   }
-               , #{ id       => els_snippets_server
-                  , start    => {els_snippets_server, start_link, []}
+               , #{ id    => els_snippets_server
+                  , start => {els_snippets_server, start_link, []}
                   }
-               , #{ id => els_bsp_client
+               , #{ id    => els_bsp_client
                   , start => {els_bsp_client, start_link, []}
                   }
-               , #{ id => els_index_buffer
-                  , start => {els_index_buffer, start, []}
+               , #{ id    => els_buffer_sup
+                  , start => {els_buffer_sup, start_link, []}
                   }
                , #{ id       => els_server
                   , start    => {els_server, start_link, []}
diff --git a/apps/els_lsp/src/els_text_search.erl b/apps/els_lsp/src/els_text_search.erl
new file mode 100644
index 000000000..c55bdd37f
--- /dev/null
+++ b/apps/els_lsp/src/els_text_search.erl
@@ -0,0 +1,46 @@
+%%==============================================================================
+%% Text-based search
+%%==============================================================================
+-module(els_text_search).
+
+%%==============================================================================
+%% API
+%%==============================================================================
+-export([ find_candidate_uris/1 ]).
+
+%%==============================================================================
+%% Includes
+%%==============================================================================
+-include("els_lsp.hrl").
+
+%%==============================================================================
+%% API
+%%==============================================================================
+-spec find_candidate_uris({els_dt_references:poi_category(), any()}) -> [uri()].
+find_candidate_uris(Id) ->
+  Pattern = extract_pattern(Id),
+  els_dt_document:find_candidates(Pattern).
+
+%%==============================================================================
+%% Internal Functions
+%%==============================================================================
+-spec extract_pattern({els_dt_references:poi_category(), any()}) ->
+        atom() | binary().
+extract_pattern({function, {_M, F, _A}}) ->
+  F;
+extract_pattern({type, {_M, F, _A}}) ->
+  F;
+extract_pattern({macro, {Name, _Arity}}) ->
+  Name;
+extract_pattern({macro, Name}) ->
+  Name;
+extract_pattern({include, Id}) ->
+  include_id(Id);
+extract_pattern({include_lib, Id}) ->
+  include_id(Id);
+extract_pattern({behaviour, Name}) ->
+  Name.
+
+-spec include_id(string()) -> string().
+include_id(Id) ->
+  filename:rootname(filename:basename(Id)).
diff --git a/apps/els_lsp/src/els_text_synchronization.erl b/apps/els_lsp/src/els_text_synchronization.erl
index abca45edf..d7a2aea86 100644
--- a/apps/els_lsp/src/els_text_synchronization.erl
+++ b/apps/els_lsp/src/els_text_synchronization.erl
@@ -30,7 +30,10 @@ did_change(Params) ->
       %% Full text sync
       #{<<"text">> := Text} = Change,
       {Duration, ok} =
-        timer:tc(fun() -> els_indexing:index(Uri, Text, 'deep') end),
+        timer:tc(fun() ->
+                     {ok, Document} = els_utils:lookup_document(Uri),
+                     els_indexing:deep_index(Document)
+                 end),
       ?LOG_DEBUG("didChange FULLSYNC [size: ~p] [duration: ~pms]\n",
                  [size(Text), Duration div 1000]),
       ok;
@@ -39,7 +42,10 @@ did_change(Params) ->
       ?LOG_DEBUG("didChange INCREMENTAL [changes: ~p]", [ContentChanges]),
       Edits = [to_edit(Change) || Change <- ContentChanges],
       {Duration, ok} =
-        timer:tc(fun() -> els_index_buffer:apply_edits_async(Uri, Edits) end),
+        timer:tc(fun() ->
+                     {ok, #{buffer := Buffer}} = els_utils:lookup_document(Uri),
+                     els_buffer_server:apply_edits(Buffer, Edits)
+                 end),
       ?LOG_DEBUG("didChange INCREMENTAL [duration: ~pms]\n",
                  [Duration div 1000]),
       ok
@@ -49,8 +55,9 @@ did_change(Params) ->
 did_open(Params) ->
   #{<<"textDocument">> := #{ <<"uri">> := Uri
                            , <<"text">> := Text}} = Params,
-  ok = els_index_buffer:load(Uri, Text),
-  ok = els_index_buffer:flush(Uri),
+  {ok, Document} = els_utils:lookup_document(Uri),
+  {ok, Buffer} = els_buffer_server:new(Uri, Text),
+  els_dt_document:insert(Document#{buffer => Buffer}),
   Provider = els_diagnostics_provider,
   els_provider:handle_request(Provider, {run_diagnostics, Params}),
   ok.
@@ -58,9 +65,7 @@ did_open(Params) ->
 -spec did_save(map()) -> ok.
 did_save(Params) ->
   #{<<"textDocument">> := #{<<"uri">> := Uri}} = Params,
-  {ok, Text} = file:read_file(els_uri:path(Uri)),
-  ok = els_index_buffer:load(Uri, Text),
-  ok = els_index_buffer:flush(Uri),
+  reload_from_disk(Uri),
   Provider = els_diagnostics_provider,
   els_provider:handle_request(Provider, {run_diagnostics, Params}),
   ok.
@@ -87,11 +92,20 @@ to_edit(#{<<"text">> := Text, <<"range">> := Range}) ->
 -spec handle_file_change(uri(), file_change_type()) -> ok.
 handle_file_change(Uri, Type) when Type =:= ?FILE_CHANGE_TYPE_CREATED;
                                    Type =:= ?FILE_CHANGE_TYPE_CHANGED ->
-  {ok, Text} = file:read_file(els_uri:path(Uri)),
-  ok = els_index_buffer:load(Uri, Text),
-  ok = els_index_buffer:flush(Uri);
+  reload_from_disk(Uri);
 handle_file_change(Uri, Type) when Type =:= ?FILE_CHANGE_TYPE_DELETED ->
-  ok = els_dt_document:delete(Uri),
-  ok = els_dt_document_index:delete_by_uri(Uri),
-  ok = els_dt_references:delete_by_uri(Uri),
-  ok = els_dt_signatures:delete_by_module(els_uri:module(Uri)).
+  els_indexing:remove(Uri).
+
+-spec reload_from_disk(uri()) -> ok.
+reload_from_disk(Uri) ->
+  {ok, Text} = file:read_file(els_uri:path(Uri)),
+  {ok, #{buffer := OldBuffer} = Document} = els_utils:lookup_document(Uri),
+  case OldBuffer of
+    undefined ->
+      els_indexing:deep_index(Document#{text => Text});
+    _ ->
+      els_buffer_server:stop(OldBuffer),
+      {ok, B} = els_buffer_server:new(Uri, Text),
+      els_indexing:deep_index(Document#{text => Text, buffer => B})
+  end,
+  ok.
diff --git a/apps/els_lsp/test/els_call_hierarchy_SUITE.erl b/apps/els_lsp/test/els_call_hierarchy_SUITE.erl
index 2242ff508..b5d5330d3 100644
--- a/apps/els_lsp/test/els_call_hierarchy_SUITE.erl
+++ b/apps/els_lsp/test/els_call_hierarchy_SUITE.erl
@@ -91,7 +91,36 @@ incoming_calls(Config) ->
           , uri => UriA},
   ?assertEqual([Item], PrepareResult),
   #{result := Result} = els_client:callhierarchy_incomingcalls(Item),
-  Calls = [#{ from =>
+  Calls = [ #{ from =>
+                 #{ data =>
+                      els_utils:base64_encode_term(
+                        #{ poi =>
+                             #{ data =>
+                                  #{ args => [{1, "Arg1"}]
+                                   , wrapping_range =>
+                                       #{ from => {7, 1}
+                                        , to => {14, 0}}}
+                              , id => {function_a, 1}
+                              , kind => function
+                              , range => #{from => {7, 1}, to => {7, 11}}}})
+                  , detail => <<"call_hierarchy_b [L11]">>
+                  , kind => 12
+                  , name => <<"function_a/1">>
+                  , range =>
+                      #{ 'end' => #{character => 29, line => 10}
+                       , start => #{character => 2, line => 10}
+                       }
+                  , selectionRange =>
+                      #{ 'end' => #{character => 29, line => 10}
+                       , start => #{character => 2, line => 10}
+                       }
+                  , uri => UriB}
+             , fromRanges =>
+                 [#{ 'end' => #{character => 29, line => 10}
+                   , start => #{character => 2, line => 10}
+                   }]
+             }
+          , #{ from =>
                 #{ data =>
                      els_utils:base64_encode_term(
                        #{ poi =>
@@ -134,37 +163,9 @@ incoming_calls(Config) ->
                 [#{ 'end' => #{character => 12, line => 15}
                   , start => #{character => 2, line => 15}
                   }]}
-          , #{ from =>
-                 #{ data =>
-                      els_utils:base64_encode_term(
-                        #{ poi =>
-                             #{ data =>
-                                  #{ args => [{1, "Arg1"}]
-                                   , wrapping_range =>
-                                       #{ from => {7, 1}
-                                        , to => {14, 0}}}
-                              , id => {function_a, 1}
-                              , kind => function
-                              , range => #{from => {7, 1}, to => {7, 11}}}})
-                  , detail => <<"call_hierarchy_b [L11]">>
-                  , kind => 12
-                  , name => <<"function_a/1">>
-                  , range =>
-                      #{ 'end' => #{character => 29, line => 10}
-                       , start => #{character => 2, line => 10}
-                       }
-                  , selectionRange =>
-                      #{ 'end' => #{character => 29, line => 10}
-                       , start => #{character => 2, line => 10}
-                       }
-                  , uri => UriB}
-             , fromRanges =>
-                 [#{ 'end' => #{character => 29, line => 10}
-                   , start => #{character => 2, line => 10}
-                   }]
-             }
           ],
-  ?assertEqual(Calls, Result).
+  [?assert(lists:member(Call, Result)) || Call <- Calls],
+  ?assertEqual(length(Calls), length(Result)).
 
 -spec outgoing_calls(config()) -> ok.
 outgoing_calls(Config) ->
diff --git a/apps/els_lsp/test/els_hover_SUITE.erl b/apps/els_lsp/test/els_hover_SUITE.erl
index 312c87184..c05887d84 100644
--- a/apps/els_lsp/test/els_hover_SUITE.erl
+++ b/apps/els_lsp/test/els_hover_SUITE.erl
@@ -375,4 +375,4 @@ has_eep48(Module) ->
   case catch code:get_doc(Module) of
     {ok, _} -> true;
     _ -> false
-  end.
\ No newline at end of file
+  end.
diff --git a/apps/els_lsp/test/els_indexer_SUITE.erl b/apps/els_lsp/test/els_indexer_SUITE.erl
index ee0adccb9..dd97c4787 100644
--- a/apps/els_lsp/test/els_indexer_SUITE.erl
+++ b/apps/els_lsp/test/els_indexer_SUITE.erl
@@ -92,7 +92,7 @@ index_dir_not_dir(Config) ->
 index_erl_file(Config) ->
   DataDir = ?config(data_dir, Config),
   Path = filename:join(els_utils:to_binary(DataDir), "test.erl"),
-  {ok, Uri} = els_indexing:index_file(Path),
+  {ok, Uri} = els_indexing:shallow_index(Path, app),
   {ok, [#{id := test, kind := module}]} = els_dt_document:lookup(Uri),
   ok.
 
@@ -100,7 +100,7 @@ index_erl_file(Config) ->
 index_hrl_file(Config) ->
   DataDir = ?config(data_dir, Config),
   Path = filename:join(els_utils:to_binary(DataDir), "test.hrl"),
-  {ok, Uri} = els_indexing:index_file(Path),
+  {ok, Uri} = els_indexing:shallow_index(Path, app),
   {ok, [#{id := test, kind := header}]} = els_dt_document:lookup(Uri),
   ok.
 
@@ -108,7 +108,7 @@ index_hrl_file(Config) ->
 index_unkown_extension(Config) ->
   DataDir = ?config(data_dir, Config),
   Path = filename:join(els_utils:to_binary(DataDir), "test.foo"),
-  {ok, Uri} = els_indexing:index_file(Path),
+  {ok, Uri} = els_indexing:shallow_index(Path, app),
   {ok, [#{kind := other}]} = els_dt_document:lookup(Uri),
   ok.
 
@@ -117,7 +117,7 @@ do_not_skip_generated_file_by_tag_by_default(Config) ->
   DataDir = data_dir(Config),
   GeneratedByTagUri = uri(DataDir, "generated_file_by_tag.erl"),
   GeneratedByCustomTagUri = uri(DataDir, "generated_file_by_custom_tag.erl"),
-  ?assertEqual({4, 0, 0}, els_indexing:index_dir(DataDir, 'deep')),
+  ?assertEqual({4, 0, 0}, els_indexing:index_dir(DataDir, app)),
   {ok, [#{ id := generated_file_by_tag
          , kind := module
          }
@@ -133,7 +133,7 @@ skip_generated_file_by_tag(Config) ->
   DataDir = data_dir(Config),
   GeneratedByTagUri = uri(DataDir, "generated_file_by_tag.erl"),
   GeneratedByCustomTagUri = uri(DataDir, "generated_file_by_custom_tag.erl"),
-  ?assertEqual({3, 1, 0}, els_indexing:index_dir(DataDir, 'deep')),
+  ?assertEqual({3, 1, 0}, els_indexing:index_dir(DataDir, app)),
   {ok, []} = els_dt_document:lookup(GeneratedByTagUri),
   {ok, [#{ id := generated_file_by_custom_tag
          , kind := module
@@ -146,7 +146,7 @@ skip_generated_file_by_custom_tag(Config) ->
   DataDir = data_dir(Config),
   GeneratedByTagUri = uri(DataDir, "generated_file_by_tag.erl"),
   GeneratedByCustomTagUri = uri(DataDir, "generated_file_by_custom_tag.erl"),
-  ?assertEqual({3, 1, 0}, els_indexing:index_dir(DataDir, 'deep')),
+  ?assertEqual({3, 1, 0}, els_indexing:index_dir(DataDir, app)),
   {ok, [#{ id := generated_file_by_tag
          , kind := module
          }
diff --git a/apps/els_lsp/test/els_indexing_SUITE.erl b/apps/els_lsp/test/els_indexing_SUITE.erl
index 212024754..40673f9d9 100644
--- a/apps/els_lsp/test/els_indexing_SUITE.erl
+++ b/apps/els_lsp/test/els_indexing_SUITE.erl
@@ -68,7 +68,7 @@ reindex_otp(_Config) ->
 
 -spec do_index_otp() -> ok.
 do_index_otp() ->
-  [els_indexing:index_dir(Dir, 'shallow') || Dir <- els_config:get(otp_paths)],
+  [els_indexing:index_dir(Dir, otp) || Dir <- els_config:get(otp_paths)],
   ok.
 
 -spec otp_apps_exclude() -> [string()].
diff --git a/apps/els_lsp/test/els_rebar3_release_SUITE.erl b/apps/els_lsp/test/els_rebar3_release_SUITE.erl
index fce638d8d..4872e2f8c 100644
--- a/apps/els_lsp/test/els_rebar3_release_SUITE.erl
+++ b/apps/els_lsp/test/els_rebar3_release_SUITE.erl
@@ -65,8 +65,8 @@ init_per_testcase(_TestCase, Config) ->
   els_client:initialize(RootUri),
   {ok, AppText} = file:read_file(els_uri:path(AppUri)),
   els_client:did_open(AppUri, erlang, 1, AppText),
-  els_indexing:find_and_index_file("rebar3_release_app.erl"),
-  els_indexing:find_and_index_file("rebar3_release_sup.erl"),
+  els_indexing:find_and_deeply_index_file("rebar3_release_app.erl"),
+  els_indexing:find_and_deeply_index_file("rebar3_release_sup.erl"),
   [{started, Started}|Config].
 
 -spec end_per_testcase(atom(), config()) -> ok.
diff --git a/apps/els_lsp/test/els_references_SUITE.erl b/apps/els_lsp/test/els_references_SUITE.erl
index eae89560c..0e5e72c09 100644
--- a/apps/els_lsp/test/els_references_SUITE.erl
+++ b/apps/els_lsp/test/els_references_SUITE.erl
@@ -27,7 +27,6 @@
         , included_record_field/1
         , undefined_record/1
         , undefined_record_field/1
-        , purge_references/1
         , type_local/1
         , type_remote/1
         , type_included/1
@@ -69,7 +68,8 @@ end_per_suite(Config) ->
 
 -spec init_per_testcase(atom(), config()) -> config().
 init_per_testcase(TestCase, Config0)
-  when TestCase =:= refresh_after_watched_file_changed ->
+  when TestCase =:= refresh_after_watched_file_changed;
+       TestCase =:= refresh_after_watched_file_deleted ->
   Config = els_test_utils:init_per_testcase(TestCase, Config0),
   PathB = ?config(watched_file_b_path, Config),
   {ok, OldContent} = file:read_file(PathB),
@@ -79,10 +79,17 @@ init_per_testcase(TestCase, Config) ->
 
 -spec end_per_testcase(atom(), config()) -> ok.
 end_per_testcase(TestCase, Config)
-  when TestCase =:= refresh_after_watched_file_changed ->
+  when TestCase =:= refresh_after_watched_file_changed;
+       TestCase =:= refresh_after_watched_file_deleted ->
   PathB = ?config(watched_file_b_path, Config),
   ok = file:write_file(PathB, ?config(old_content, Config)),
   els_test_utils:end_per_testcase(TestCase, Config);
+end_per_testcase(TestCase, Config)
+  when TestCase =:= refresh_after_watched_file_added ->
+  PathB = ?config(watched_file_b_path, Config),
+  ok = file:delete(filename:join(filename:dirname(PathB),
+                                 "watched_file_c.erl")),
+  els_test_utils:end_per_testcase(TestCase, Config);
 end_per_testcase(TestCase, Config) ->
   els_test_utils:end_per_testcase(TestCase, Config).
 
@@ -413,34 +420,6 @@ undefined_record_field(Config) ->
   assert_locations(Locations1, ExpectedLocations),
   ok.
 
-%% Issue #245
--spec purge_references(config()) -> ok.
-purge_references(_Config) ->
-  els_db:clear_tables(),
-  Uri   = <<"file:///tmp/foo.erl">>,
-  Text0 = <<"-spec foo() -> ok.\nfoo(_X) -> ok.\nbar() -> foo().">>,
-  Text1 = <<"\n-spec foo() -> ok.\nfoo(_X)-> ok.\nbar() -> foo().">>,
-  Doc0  = els_dt_document:new(Uri, Text0),
-  Doc1  = els_dt_document:new(Uri, Text1),
-
-  ok = els_indexing:index(Uri, Text0, 'deep'),
-  ?assertEqual({ok, [Doc0]}, els_dt_document:lookup(Uri)),
-  ?assertEqual({ok, [#{ id    => {foo, foo, 0}
-                      , range => #{from => {3, 10}, to => {3, 13}}
-                      , uri   => <<"file:///tmp/foo.erl">>
-                      }]}
-              , els_dt_references:find_all()
-              ),
-
-  ok = els_indexing:index(Uri, Text1, 'deep'),
-  ?assertEqual({ok, [Doc1]}, els_dt_document:lookup(Uri)),
-  ?assertEqual({ok, [#{ id    => {foo, foo, 0}
-                      , range => #{from => {4, 10}, to => {4, 13}}
-                      , uri   => <<"file:///tmp/foo.erl">>
-                      }]}
-              , els_dt_references:find_all()
-              ),
-  ok.
 
 -spec type_local(config()) -> ok.
 type_local(Config) ->
@@ -507,6 +486,7 @@ refresh_after_watched_file_deleted(Config) ->
   %% Before
   UriA = ?config(watched_file_a_uri, Config),
   UriB = ?config(watched_file_b_uri, Config),
+  PathB = ?config(watched_file_b_path, Config),
   ExpectedLocationsBefore = [ #{ uri   => UriB
                                , range => #{from => {6, 3}, to => {6, 22}}
                                }
@@ -514,6 +494,7 @@ refresh_after_watched_file_deleted(Config) ->
   #{result := LocationsBefore} = els_client:references(UriA, 5, 2),
   assert_locations(LocationsBefore, ExpectedLocationsBefore),
   %% Delete (Simulate a checkout, rebase or similar)
+  ok = file:delete(PathB),
   els_client:did_change_watched_files([{UriB, ?FILE_CHANGE_TYPE_DELETED}]),
   %% After
   #{result := null} = els_client:references(UriA, 5, 2),
@@ -554,6 +535,7 @@ refresh_after_watched_file_added(Config) ->
   %% Before
   UriA = ?config(watched_file_a_uri, Config),
   UriB = ?config(watched_file_b_uri, Config),
+  PathB = ?config(watched_file_b_path, Config),
   ExpectedLocationsBefore = [ #{ uri   => UriB
                                , range => #{from => {6, 3}, to => {6, 22}}
                                }
@@ -563,10 +545,12 @@ refresh_after_watched_file_added(Config) ->
   %% Add (Simulate a checkout, rebase or similar)
   DataDir = ?config(data_dir, Config),
   PathC = filename:join([DataDir, "watched_file_c.erl"]),
-  UriC = els_uri:uri(els_utils:to_binary(PathC)),
-  els_client:did_change_watched_files([{UriC, ?FILE_CHANGE_TYPE_CREATED}]),
+  NewPathC = filename:join(filename:dirname(PathB), "watched_file_c.erl"),
+  NewUriC = els_uri:uri(NewPathC),
+  {ok, _} = file:copy(PathC, NewPathC),
+  els_client:did_change_watched_files([{NewUriC, ?FILE_CHANGE_TYPE_CREATED}]),
   %% After
-  ExpectedLocationsAfter = [ #{ uri   => UriC
+  ExpectedLocationsAfter = [ #{ uri   => NewUriC
                               , range => #{from => {6, 3}, to => {6, 22}}
                               }
                            , #{ uri   => UriB
diff --git a/apps/els_lsp/test/els_test_utils.erl b/apps/els_lsp/test/els_test_utils.erl
index 2d96aa3a1..a2fe3d11e 100644
--- a/apps/els_lsp/test/els_test_utils.erl
+++ b/apps/els_lsp/test/els_test_utils.erl
@@ -130,7 +130,8 @@ includes() ->
 %%      accessing this information from test cases.
 -spec index_file(binary()) -> [{atom(), any()}].
 index_file(Path) ->
-  {ok, Uri} = els_indexing:index_file(Path),
+  Uri = els_uri:uri(Path),
+  ok = els_indexing:ensure_deeply_indexed(Uri),
   {ok, Text} = file:read_file(Path),
   ConfigId = config_id(Path),
   [ {atoms_append(ConfigId, '_path'), Path}