Don't store `{0,0,[]}` for views with new results

This saves us a key/value pair for any document that is not included as
part of a view.

2 files changed, 10 insertions, 2 deletions

diff --git a/src/couch_views/src/couch_views_fdb.erl b/src/couch_views/src/couch_views_fdb.erl
index 98257f308..a0224b2b8 100644
--- a/src/couch_views/src/couch_views_fdb.erl
+++ b/src/couch_views/src/couch_views_fdb.erl
@@ -205,6 +205,14 @@ clear_map_idx(TxDb, Sig, ViewId, DocId, ViewKeys) ->
     end, ViewKeys).
 
 
+update_id_idx(TxDb, Sig, ViewId, DocId, [], _KVSize) ->
+    #{
+        tx := Tx,
+        db_prefix := DbPrefix
+    } = TxDb,
+    Key = id_idx_key(DbPrefix, Sig, DocId, ViewId),
+    ok = erlfdb:clear(Tx, Key);
+
 update_id_idx(TxDb, Sig, ViewId, DocId, NewRows, KVSize) ->
     #{
         tx := Tx,
diff --git a/src/couch_views/test/couch_views_indexer_test.erl b/src/couch_views/test/couch_views_indexer_test.erl
index c3f704911..cd5b2b0bf 100644
--- a/src/couch_views/test/couch_views_indexer_test.erl
+++ b/src/couch_views/test/couch_views_indexer_test.erl
@@ -161,7 +161,7 @@ updated_docs_are_reindexed(Db) ->
     Sig = Mrst#mrst.sig,
     fabric2_fdb:transactional(Db, fun(TxDb) ->
         ?assertMatch(
-                [{0, 1, _, [1]}, {1, 0, 0, []}],
+                [{0, 1, _, [1]}],
                 couch_views_fdb:get_view_keys(TxDb, Sig, <<"0">>)
             )
     end).
@@ -217,7 +217,7 @@ updated_docs_without_changes_are_reindexed(Db) ->
     Sig = Mrst#mrst.sig,
     fabric2_fdb:transactional(Db, fun(TxDb) ->
         ?assertMatch(
-                [{0, 1, _, [0]}, {1, 0, 0, []}],
+                [{0, 1, _, [0]}],
                 couch_views_fdb:get_view_keys(TxDb, Sig, <<"0">>)
             )
     end).