Do not use fetch join, as even with the N+1 problem the queries are faster than with the very complex and slow expressions needed for the fetch Join pagination

src/DataTables/Adapters/FetchResultsAtOnceORMAdapter.php

@@ -0,0 +1,69 @@
+<?php
+/*
+ * This file is part of Part-DB (https://github.com/Part-DB/Part-DB-symfony).
+ *
+ *  Copyright (C) 2019 - 2023 Jan Böhmer (https://github.com/jbtronics)
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as published
+ *  by the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+
+namespace App\DataTables\Adapters;
+
+use App\DataTables\Events\ORMPostQueryEvent;
+use Doctrine\ORM\AbstractQuery;
+use Doctrine\ORM\QueryBuilder;
+use Omines\DataTablesBundle\Adapter\AdapterQuery;
+use Omines\DataTablesBundle\Adapter\Doctrine\Event\ORMAdapterQueryEvent;
+use Omines\DataTablesBundle\Adapter\Doctrine\ORMAdapter;
+use Omines\DataTablesBundle\Adapter\Doctrine\ORMAdapterEvents;
+use Omines\DataTablesBundle\Column\AbstractColumn;
+
+/**
+ * This class is very similar to the original ORMAdapter, but instead of getting each line one by one, it gets all the results at once,
+ * which can save some time in combination with fetch hints.
+ */
+class FetchResultsAtOnceORMAdapter extends ORMAdapter
+{
+    protected function getResults(AdapterQuery $query): \Traversable
+    {
+        /** @var QueryBuilder $builder */
+        $builder = $query->get('qb');
+        $state = $query->getState();
+
+        // Apply definitive view state for current 'page' of the table
+        foreach ($state->getOrderBy() as list($column, $direction)) {
+            /** @var AbstractColumn $column */
+            if ($column->isOrderable()) {
+                $builder->addOrderBy($column->getOrderField(), $direction);
+            }
+        }
+        if (null !== $state->getLength()) {
+            $builder
+                ->setFirstResult($state->getStart())
+                ->setMaxResults($state->getLength())
+            ;
+        }
+
+        $q = $builder->getQuery();
+        $event = new ORMAdapterQueryEvent($q);
+        $state->getDataTable()->getEventDispatcher()->dispatch($event, ORMAdapterEvents::PRE_QUERY);
+
+        foreach ($q->getResult() as $item) {
+            yield $item;
+        }
+    }
+}