Try reverting prefetch changes for project/version listing views

readthedocs/builds/models.py

@@ -207,9 +207,6 @@ class Meta:
         unique_together = [("project", "slug")]
         ordering = ["-verbose_name"]
 
-    # Property used for prefetching version related fields
-    LATEST_BUILD_CACHE = "_latest_build"
-
     def __str__(self):
         return self.verbose_name
 
@@ -300,13 +297,6 @@ def last_build(self):
 
     @property
     def latest_build(self):
-        # Check if there is `_latest_build` prefetch in the Queryset.
-        # Used for database optimization.
-        if hasattr(self, self.LATEST_BUILD_CACHE):
-            if latest_build := getattr(self, self.LATEST_BUILD_CACHE):
-                return latest_build[0]
-            return None
-
         return self.builds.order_by("-date").first()
 
     @property

readthedocs/builds/querysets.py

@@ -3,7 +3,7 @@
 
 import structlog
 from django.db import models
-from django.db.models import OuterRef, Prefetch, Q, Subquery
+from django.db.models import Q
 from django.utils import timezone
 
 from readthedocs.builds.constants import (
@@ -141,30 +141,6 @@ def for_reindex(self):
             .distinct()
         )
 
-    def prefetch_subquery(self):
-        """
-        Prefetch related objects via subquery for each version.
-
-        .. note::
-
-            This should come after any filtering.
-        """
-        from readthedocs.builds.models import Build
-
-        # Prefetch the latest build for each project.
-        subquery_builds = Subquery(
-            Build.internal.filter(version=OuterRef("version_id"))
-            .order_by("-date")
-            .values_list("id", flat=True)[:1]
-        )
-        prefetch_builds = Prefetch(
-            "builds",
-            Build.internal.filter(pk__in=subquery_builds),
-            to_attr=self.model.LATEST_BUILD_CACHE,
-        )
-
-        return self.prefetch_related(prefetch_builds)
-
 
 class VersionQuerySet(SettingsOverrideObject):
     _default_class = VersionQuerySetBase

readthedocs/projects/models.py

@@ -575,7 +575,6 @@ class Project(models.Model):
 
     # Property used for storing the latest build for a project when prefetching
     LATEST_BUILD_CACHE = "_latest_build"
-    LATEST_SUCCESSFUL_BUILD_CACHE = "_latest_successful_build"
 
     class Meta:
         ordering = ("slug",)
@@ -921,13 +920,6 @@ def conf_dir(self, version=LATEST):
 
     @property
     def has_good_build(self):
-        # Check if there is `_latest_successful_build` attribute in the Queryset.
-        # Used for database optimization.
-        if hasattr(self, self.LATEST_SUCCESSFUL_BUILD_CACHE):
-            if build_successful := getattr(self, self.LATEST_SUCCESSFUL_BUILD_CACHE):
-                return build_successful[0]
-            return None
-
         # Check if there is `_good_build` annotation in the Queryset.
         # Used for Database optimization.
         if hasattr(self, "_good_build"):

readthedocs/projects/querysets.py

@@ -132,39 +132,26 @@ def prefetch_latest_build(self):
         from readthedocs.builds.models import Build
 
         # Prefetch the latest build for each project.
-        subquery_build_latest = Subquery(
+        subquery = Subquery(
             Build.internal.filter(project=OuterRef("project_id"))
             .order_by("-date")
             .values_list("id", flat=True)[:1]
         )
-        prefetch_build_latest = Prefetch(
+        latest_build = Prefetch(
             "builds",
-            Build.internal.filter(pk__in=subquery_build_latest),
+            Build.internal.filter(pk__in=subquery),
             to_attr=self.model.LATEST_BUILD_CACHE,
         )
-
-        # Prefetch the latest successful build for each project.
-        subquery_build_successful = Subquery(
-            Build.internal.filter(project=OuterRef("project_id"))
-            .order_by("-date")
-            .values_list("id", flat=True)[:1]
-        )
-        prefetch_build_successful = Prefetch(
-            "builds",
-            Build.internal.filter(pk__in=subquery_build_successful),
-            to_attr=self.model.LATEST_SUCCESSFUL_BUILD_CACHE,
-        )
-
-        return self.prefetch_related(
-            prefetch_build_latest,
-            prefetch_build_successful,
-        )
+        return self.prefetch_related(latest_build)
 
     # Aliases
 
     def dashboard(self, user):
         """Get the projects for this user including the latest build."""
-        return self.for_user(user).prefetch_latest_build()
+        # Prefetching seems to cause some inconsistent performance issues,
+        # disabling for now. For more background, see:
+        # https://github.com/readthedocs/readthedocs.org/pull/11621
+        return self.for_user(user)
 
     def api(self, user=None):
         return self.public(user)

readthedocs/projects/views/public.py

@@ -123,11 +123,7 @@ def get_context_data(self, **kwargs):
                 queryset=versions,
                 project=project,
             )
-            versions = (
-                self.get_filtered_queryset()
-                .prefetch_related("project")
-                .prefetch_subquery()
-            )
+            versions = self.get_filtered_queryset()
         context["versions"] = versions
 
         protocol = "http"