Merge pull request #414 from sparcs-kaist/fix/slow-query

Fix slow query caused by GET /articles

apps/core/migrations/0057_alter_article_name_type_and_more.py

@@ -0,0 +1,30 @@
+# Generated by Django 4.2.3 on 2023-09-21 08:27
+
+from django.db import migrations, models
+
+import apps.core.models.board
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("core", "0056_alter_article_comment_count_alter_article_hit_count_and_more"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="article",
+            name="name_type",
+            field=models.PositiveSmallIntegerField(
+                db_index=True,
+                default=apps.core.models.board.NameType["REGULAR"],
+                verbose_name="익명 혹은 실명 여부",
+            ),
+        ),
+        migrations.AddIndex(
+            model_name="article",
+            index=models.Index(
+                fields=["created_at", "parent_board_id"],
+                name="created_at_parent_board_id_idx",
+            ),
+        ),
+    ]

apps/core/models/article.py

@@ -21,7 +21,7 @@
 )
 
 from .block import Block
-from .board import NameType, BoardAccessPermissionType
+from .board import BoardAccessPermissionType, NameType
 from .comment import Comment
 from .communication_article import SchoolResponseStatus
 from .report import Report
@@ -52,6 +52,7 @@ class Article(MetaDataModel):
     name_type = models.PositiveSmallIntegerField(
         verbose_name="익명 혹은 실명 여부",
         default=NameType.REGULAR,
+        db_index=True,
     )
     is_content_sexual = models.BooleanField(
         verbose_name="성인/음란성 내용",
@@ -157,6 +158,13 @@ class Meta(MetaDataModel.Meta):
         verbose_name = "게시물"
         verbose_name_plural = "게시물 목록"
 
+        indexes = [
+            models.Index(
+                fields=["created_at", "parent_board_id"],
+                name="created_at_parent_board_id_idx",
+            )
+        ]
+
     def __str__(self):
         return self.title
 

apps/core/views/viewsets/article.py

@@ -1,7 +1,9 @@
 import time
 
+from django.core.paginator import Paginator as DjangoPaginator
 from django.db import models
 from django.http import Http404
+from django.utils.functional import cached_property
 from django.utils.translation import gettext
 from rest_framework import (
     decorators,
@@ -78,40 +80,71 @@ class ArticleViewSet(viewsets.ModelViewSet, ActionAPIViewSet):
         ),
     }
 
+    # Override list action for further optimization
+    def list(self, request):
+        queryset = self.filter_queryset(self.get_queryset())
+
+        created_by = self.request.query_params.get("created_by")
+        if created_by and int(created_by) != self.request.user.id:
+            # exclude someone's anonymous or realname article in one's profile
+            exclude_list = [NameType.ANONYMOUS, NameType.REALNAME]
+            queryset = queryset.exclude(name_type__in=exclude_list)
+
+        # Compute `count` here to optimize query
+        count = (
+            queryset.count()
+            - queryset.filter(
+                created_by__id__in=self.request.user.block_set.values("user"),
+                name_type=NameType.ANONYMOUS,
+            ).count()
+        )
+
+        # exclude article written by blocked users in anonymous board
+        queryset = queryset.exclude(
+            created_by__id__in=self.request.user.block_set.values("user"),
+            name_type=NameType.ANONYMOUS,
+        )
+
+        queryset = queryset.prefetch_related(
+            "attachments",
+            "communication_article",
+        )
+
+        # optimizing queryset for list action
+        queryset = queryset.select_related(
+            "created_by",
+            "created_by__profile",
+            "parent_topic",
+            "parent_board",
+            "parent_board__group",
+        ).prefetch_related(
+            ArticleReadLog.prefetch_my_article_read_log(self.request.user),
+        )
+
+        class Paginator(DjangoPaginator):
+            @cached_property
+            def count(self):
+                return count
+
+        # Originated from list function of rest_framework.mixins.ListModelMixin
+        page = self.paginator.paginate_queryset(
+            queryset, request, paginator_class=Paginator
+        )
+        if page is not None:
+            serializer = self.get_serializer(page, many=True)
+            return self.get_paginated_response(serializer.data)
+
+        serializer = self.get_serializer(queryset, many=True)
+        return Response(serializer.data)
+
     def filter_queryset(self, queryset):
         queryset = super().filter_queryset(queryset)
 
         if self.action == "destroy":
             pass
 
         elif self.action == "list":
-            created_by = self.request.query_params.get("created_by")
-            if created_by and int(created_by) != self.request.user.id:
-                # exclude someone's anonymous or realname article in one's profile
-                exclude_list = [NameType.ANONYMOUS, NameType.REALNAME]
-                queryset = queryset.exclude(name_type__in=exclude_list)
-
-            # exclude article written by blocked users in anonymous board
-            queryset = queryset.exclude(
-                created_by__id__in=self.request.user.block_set.values("user"),
-                name_type=NameType.ANONYMOUS,
-            )
-
-            queryset = queryset.prefetch_related(
-                "attachments",
-                "communication_article",
-            )
-
-            # optimizing queryset for list action
-            queryset = queryset.select_related(
-                "created_by",
-                "created_by__profile",
-                "parent_topic",
-                "parent_board",
-                "parent_board__group",
-            ).prefetch_related(
-                ArticleReadLog.prefetch_my_article_read_log(self.request.user),
-            )
+            pass
 
         # optimizing queryset for create, update, retrieve actions
         else:

ara/classes/pagination.py

@@ -1,11 +1,40 @@
 from collections import OrderedDict
 
+from django.core.paginator import InvalidPage
 from rest_framework import pagination, response
+from rest_framework.exceptions import NotFound
 
 
 class PageNumberPagination(pagination.PageNumberPagination):
     page_size_query_param = "page_size"
 
+    # Originated from rest_framework.pagination.PageNumberPagination
+    def paginate_queryset(self, queryset, request, view=None, paginator_class=None):
+        page_size = self.get_page_size(request)
+        if not page_size:
+            return None
+
+        paginator_class = (
+            paginator_class if paginator_class else self.django_paginator_class
+        )
+        paginator = paginator_class(queryset, page_size)
+        page_number = self.get_page_number(request, paginator)
+
+        try:
+            self.page = paginator.page(page_number)
+        except InvalidPage as exc:
+            msg = self.invalid_page_message.format(
+                page_number=page_number, message=str(exc)
+            )
+            raise NotFound(msg)
+
+        if paginator.num_pages > 1 and self.template is not None:
+            # The browsable API should display pagination controls.
+            self.display_page_controls = True
+
+        self.request = request
+        return list(self.page)
+
     def get_paginated_response(self, data):
         return response.Response(
             OrderedDict(