Merge pull request #3839 from bjester/channel-list-query

Optimize use of channel in unpublished_changes query
learningequality · Nov 23, 2022 · 2b1f10b · 2b1f10b
2 parents 4acc580 + 76e8ce5
commit 2b1f10b
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Showing 2 changed files with 23 additions and 8 deletions.
diff --git a/...entcuration/contentcuration/frontend/channelEdit/views/ImportFromChannels/ChannelList.vue b/...entcuration/contentcuration/frontend/channelEdit/views/ImportFromChannels/ChannelList.vue
@@ -124,6 +124,7 @@
           [this.channelFilter]: true,
           page: this.$route.query.page || 1,
           exclude: this.currentChannelId,
+          ordering: this.channelFilter === 'public' ? 'name' : '-modified',
         }).then(page => {
           this.pageCount = page.total_pages;
           this.channels = page.results;

diff --git a/contentcuration/contentcuration/viewsets/channel.py b/contentcuration/contentcuration/viewsets/channel.py
@@ -382,9 +382,18 @@ def format_demo_server_url(item):
 
 
 def _unpublished_changes_query(channel):
+    """
+    :param channel: Either an `OuterRef` or `Channel` object
+    :type channel: Channel|OuterRef
+    :return: QuerySet for unpublished changes
+    """
+    # double wrap the channel if it's an outer ref so that we can match the outermost channel
+    # to optimize query performance
+    channel_ref = OuterRef(channel) if isinstance(channel, OuterRef) else channel
+
     return Change.objects.filter(
         server_rev__gt=Coalesce(Change.objects.filter(
-            channel=OuterRef("channel"),
+            channel=channel_ref,
             change_type=PUBLISHED,
             errored=False
         ).values("server_rev").order_by("-server_rev")[:1], Value(0)),
@@ -400,6 +409,8 @@ class ChannelViewSet(ValuesViewset):
     serializer_class = ChannelSerializer
     pagination_class = ChannelListPagination
     filterset_class = ChannelFilter
+    ordering_fields = ["modified", "name"]
+    ordering = "-modified"
 
     field_map = channel_field_map
     values = base_channel_values + ("edit", "view", "unpublished_changes")
@@ -412,6 +423,15 @@ def get_queryset(self):
         queryset = super(ChannelViewSet, self).get_queryset()
         user_id = not self.request.user.is_anonymous and self.request.user.id
         user_queryset = User.objects.filter(id=user_id)
+        # Add the last modified node modified value as the channel last modified
+        channel_main_tree_nodes = ContentNode.objects.filter(
+            tree_id=OuterRef("main_tree__tree_id")
+        )
+        queryset = queryset.annotate(
+            modified=Subquery(
+                channel_main_tree_nodes.values("modified").order_by("-modified")[:1]
+            )
+        )
 
         return queryset.annotate(
             edit=Exists(user_queryset.filter(editable_channels=OuterRef("id"))),
@@ -434,12 +454,6 @@ def annotate_queryset(self, queryset):
         queryset = queryset.annotate(
             count=SQCount(non_topic_content_ids, field="content_id"),
         )
-        # Add the last modified node modified value as the channel last modified
-        queryset = queryset.annotate(
-            modified=Subquery(
-                channel_main_tree_nodes.values("modified").order_by("-modified")[:1]
-            )
-        )
 
         queryset = queryset.annotate(unpublished_changes=Exists(_unpublished_changes_query(OuterRef("id"))))
 
@@ -488,7 +502,7 @@ def publish(self, pk, version_notes="", language=None):
                             "publishing": False,
                             "primary_token": channel.get_human_token().token,
                             "last_published": channel.last_published,
-                            "unpublished_changes": _unpublished_changes_query(channel.id).exists()
+                            "unpublished_changes": _unpublished_changes_query(channel).exists()
                         }, channel_id=channel.id
                     ),
                 ], applied=True)