diff --git a/lib/private/DB/QueryBuilder/Partitioned/PartitionQuery.php b/lib/private/DB/QueryBuilder/Partitioned/PartitionQuery.php
index 9e97bce67b910..74357870a56d7 100644
--- a/lib/private/DB/QueryBuilder/Partitioned/PartitionQuery.php
+++ b/lib/private/DB/QueryBuilder/Partitioned/PartitionQuery.php
@@ -23,6 +23,7 @@
 
 namespace OC\DB\QueryBuilder\Partitioned;
 
+use OC\DB\QueryBuilder\Sharded\ShardedQueryBuilder;
 use OCP\DB\QueryBuilder\IQueryBuilder;
 
 class PartitionQuery {
@@ -34,7 +35,7 @@ class PartitionQuery {
 	public const JOIN_MODE_RIGHT = 'right';
 
 	public function __construct(
-		public IQueryBuilder $query,
+		public ShardedQueryBuilder $query,
 		public string $joinFromColumn,
 		public string $joinToColumn,
 		public string $joinMode,
@@ -55,8 +56,14 @@ public function mergeWith(array $rows): array {
 		$joinFromValues = array_map(function (array $row) use ($joinFromColumn) {
 			return $row[$joinFromColumn];
 		}, $rows);
+		$joinFromValues = array_filter($joinFromValues, function($value) {
+			return $value !== null;
+		});
 		$this->query->andWhere($this->query->expr()->in($this->joinToColumn, $this->query->createNamedParameter($joinFromValues, IQueryBuilder::PARAM_STR_ARRAY, ':' . uniqid())));
 
+		$columns = $this->query->getOutputColumns();
+		$nullResult = array_combine($this->query->getOutputColumns(), array_fill(0, count($columns), null));
+
 		$s = $this->query->getSQL();
 		$partitionedRows = $this->query->executeQuery()->fetchAll();
 		$partitionedRowsByKey = [];
@@ -70,7 +77,7 @@ public function mergeWith(array $rows): array {
 					$result[] = array_merge($row, $partitionedRowsByKey[$row[$joinFromColumn]]);
 				}
 			} elseif ($this->joinMode === self::JOIN_MODE_LEFT || $this->joinMode === self::JOIN_MODE_LEFT_NULL) {
-				$result[] = $row;
+				$result[] = array_merge($nullResult, $row);
 			}
 		}
 		return $result;
diff --git a/lib/private/DB/QueryBuilder/Sharded/ShardedQueryBuilder.php b/lib/private/DB/QueryBuilder/Sharded/ShardedQueryBuilder.php
index 5fdd59951502a..2514e64e86492 100644
--- a/lib/private/DB/QueryBuilder/Sharded/ShardedQueryBuilder.php
+++ b/lib/private/DB/QueryBuilder/Sharded/ShardedQueryBuilder.php
@@ -34,6 +34,7 @@ class ShardedQueryBuilder extends ExtendedQueryBuilder {
 	private mixed $lastInsertId = null;
 	private ?IDBConnection $lastInsertConnection = null;
 	private ?int $updateShardKey = null;
+	private array $outputColumns = [];
 
 	/**
 	 * @param ConnectionAdapter $connection
@@ -83,6 +84,40 @@ private function getKeyValue($value): array {
 		}
 	}
 
+	public function select(...$selects) {
+		$this->addOutputColumns($selects);
+		return parent::select(...$selects);
+	}
+
+	public function selectAlias($select, $alias) {
+		$this->addOutputColumns([$alias]);
+		return parent::selectAlias($select, $alias);
+	}
+
+	public function selectDistinct($select) {
+		$this->addOutputColumns([$select]);
+		return parent::selectDistinct($select);
+	}
+
+	public function addSelect(...$select) {
+		$this->addOutputColumns($select);
+		return parent::addSelect(...$select);
+	}
+
+	private function addOutputColumns(array $columns) {
+		foreach ($columns as $column) {
+			if (is_array($column)) {
+				$this->addOutputColumns($column);
+			} elseif (is_string($column) && !str_contains($column, '*')) {
+				if (str_contains($column, '.')) {
+					[, $column] = explode('.', $column);
+				}
+				$this->outputColumns[] = $column;
+			}
+		}
+	}
+
+
 	public function where(...$predicates) {
 		return $this->andWhere(...$predicates);
 	}
@@ -371,5 +406,14 @@ public function getLastInsertId(): int {
 		}
 	}
 
-
+	public function getOutputColumns(): array {
+		return array_unique(array_map(function(string $column) {
+			if (str_contains($column, '.')) {
+				[, $column] = explode('.', $column);
+				return $column;
+			} else {
+				return $column;
+			}
+		}, $this->outputColumns));
+	}
 }