fix: query portable across all supported DBAL drivers

Author: solracsf

lib/private/Files/Cache/Cache.php

@@ -1015,7 +1015,6 @@ public function calculateFolderSize($path, $entry = null) {
 	/**
 	 * inner function because we can't add new params to the public function without breaking any child classes
 	 *
-	 * @param string $path
 	 * @param array|null|ICacheEntry $entry (optional) meta data of the folder
 	 * @param bool $ignoreUnknown don't mark the folder size as unknown if any of it's children are unknown
 	 * @return int|float
@@ -1031,14 +1030,6 @@ protected function calculateFolderSizeInner(string $path, $entry = null, bool $i
 			$query = $this->getQueryBuilder();
 			$query->selectAlias($query->func()->sum('size'), 'size_sum')
 				->selectAlias($query->func()->min('size'), 'size_min')
-				->selectAlias(
-					$query->createFunction('SUM(CASE WHEN unencrypted_size > 0 THEN unencrypted_size ELSE size END)'),
-					'unencrypted_sum'
-				)
-				->selectAlias(
-					$query->createFunction('MIN(CASE WHEN unencrypted_size > 0 THEN unencrypted_size ELSE size END)'),
-					'unencrypted_min'
-				)
 				->selectAlias($query->func()->max('unencrypted_size'), 'unencrypted_max')
 				->from('filecache')
 				->whereStorageId($this->getNumericStorageId())
@@ -1055,17 +1046,33 @@ protected function calculateFolderSizeInner(string $path, $entry = null, bool $i
 			if ($agg && $agg['size_sum'] !== null) {
 				$sum = Util::numericToNumber($agg['size_sum']);
 				$min = Util::numericToNumber($agg['size_min']);
-				$unencryptedSum = Util::numericToNumber($agg['unencrypted_sum']);
-				$unencryptedMin = Util::numericToNumber($agg['unencrypted_min']);
 				$unencryptedMax = Util::numericToNumber($agg['unencrypted_max'] ?? 0);
 
 				$sum = 0 + $sum;
 				$min = 0 + $min;
-				if ($min === -1) {
-					$totalSize = $min;
-				} else {
-					$totalSize = $sum;
+				$totalSize = ($min === -1) ? $min : $sum;
+
+				$query = $this->getQueryBuilder();
+				$query->select('size', 'unencrypted_size')
+					->from('filecache')
+					->whereStorageId($this->getNumericStorageId())
+					->whereParent($id);
+				if ($ignoreUnknown) {
+					$query->andWhere($query->expr()->gte('size', $query->createNamedParameter(0)));
 				}
+				$result = $query->executeQuery();
+				$rows = $result->fetchAll();
+				$result->closeCursor();
+
+				$unencryptedSizes = array_map(function (array $row) {
+					$u = Util::numericToNumber($row['unencrypted_size']);
+					$s = Util::numericToNumber($row['size']);
+					return ($u > 0) ? $u : $s;
+				}, $rows);
+
+				$unencryptedSum = array_sum($unencryptedSizes);
+				$unencryptedMin = $unencryptedSizes ? min($unencryptedSizes) : 0;
+
 				if ($unencryptedMin === -1 || $min === -1) {
 					$unencryptedTotal = $unencryptedMin;
 				} else {
@@ -1077,15 +1084,16 @@ protected function calculateFolderSizeInner(string $path, $entry = null, bool $i
 				$unencryptedMax = 0;
 			}
 
-			// only set unencrypted size for a folder if any child entries have it set, or the folder is empty
+			// only set unencrypted size for a folder if any child entries have it set
+			// or if the folder is empty
 			$shouldWriteUnEncryptedSize = $unencryptedMax > 0 || $totalSize === 0 || ($entry['unencrypted_size'] ?? 0) > 0;
 			if ($entry['size'] !== $totalSize || (($entry['unencrypted_size'] ?? 0) !== $unencryptedTotal && $shouldWriteUnEncryptedSize)) {
 				if ($shouldWriteUnEncryptedSize) {
-					// if all children have an unencrypted size of 0, just set the folder unencrypted size to 0 instead of summing the sizes
+					// if all children have an unencrypted size of 0
+					// just set the folder unencrypted size to 0 instead of summing the sizes
 					if ($unencryptedMax === 0) {
 						$unencryptedTotal = 0;
 					}
-
 					$this->update($id, [
 						'size' => $totalSize,
 						'unencrypted_size' => $unencryptedTotal,