perf: optimize querying post index

Author: SychO9

framework/core/src/Api/Resource/PostResource.php

@@ -129,16 +129,16 @@ public function endpoints(): array
                         $sort = $defaultExtracts['sort'];
                         $filter = $defaultExtracts['filter'];
 
-                        if (count($filter) > 1 || ! isset($filter['discussion']) || $sort) {
+                        if (count($filter) > 1 || ! isset($filter['discussion']) || ($sort && $sort !== ['number' => 'asc'])) {
                             throw new BadRequestException(
                                 'You can only use page[near] with filter[discussion] and the default sort order'
                             );
                         }
 
                         $limit = $defaultExtracts['limit'];
-                        $offset = $this->posts->getIndexForNumber((int) $filter['discussion'], $near, $context->getActor());
+                        $index = $this->posts->getIndexForNumber((int) $filter['discussion'], $near, $context->getActor());
 
-                        return max(0, $offset - $limit / 2);
+                        return max(0, $index - $limit / 2);
                     }
 
                     return $defaultExtracts['offset'];
@@ -150,6 +150,7 @@ public function endpoints(): array
                     'hiddenUser',
                     'discussion'
                 ])
+                ->defaultSort('number')
                 ->paginate(static::$defaultLimit),
         ];
     }

framework/core/src/Post/PostRepository.php

@@ -85,23 +85,15 @@ public function filterVisibleIds(array $ids, User $actor): array
      */
     public function getIndexForNumber(int $discussionId, int $number, ?User $actor = null): int
     {
+        /** @var Discussion $discussion */
         if (! ($discussion = Discussion::find($discussionId))) {
             return 0;
         }
 
         $query = $discussion->posts()
             ->whereVisibleTo($actor)
-            ->where('created_at', '<', function ($query) use ($discussionId, $number) {
-                $query->select('created_at')
-                    ->from('posts')
-                    ->where('discussion_id', $discussionId)
-                    ->whereNotNull('number')
-                    ->take(1)
-
-                    // We don't add $number as a binding because for some
-                    // reason doing so makes the bindings go out of order.
-                    ->orderByRaw('ABS(CAST(number AS SIGNED) - '.(int) $number.')');
-            });
+            ->where('number', '<=', $number)
+            ->orderBy('number');
 
         return $query->count();
     }