diff --git a/core/BackgroundJobs/PreviewMigrationJob.php b/core/BackgroundJobs/PreviewMigrationJob.php
index 5ca3de9286a..9a9e64b9703 100644
--- a/core/BackgroundJobs/PreviewMigrationJob.php
+++ b/core/BackgroundJobs/PreviewMigrationJob.php
@@ -12,11 +12,10 @@ namespace OC\Core\BackgroundJobs;
 use OC\Preview\PreviewMigrationService;
 use OCP\AppFramework\Utility\ITimeFactory;
 use OCP\BackgroundJob\TimedJob;
-use OCP\DB\IResult;
+use OCP\Files\FileInfo;
 use OCP\Files\IRootFolder;
 use OCP\IAppConfig;
 use OCP\IConfig;
-use OCP\IDBConnection;
 use Override;
 use Psr\Log\LoggerInterface;
 
@@ -27,7 +26,6 @@ class PreviewMigrationJob extends TimedJob {
 		ITimeFactory $time,
 		private readonly IAppConfig $appConfig,
 		private readonly IConfig $config,
-		private readonly IDBConnection $connection,
 		private readonly IRootFolder $rootFolder,
 		private readonly PreviewMigrationService $migrationService,
 		private readonly LoggerInterface $logger,
@@ -45,79 +43,60 @@ class PreviewMigrationJob extends TimedJob {
 			return;
 		}
 
-		$startTime = time();
-		while (true) {
-			$qb = $this->connection->getQueryBuilder();
-			$qb->select('path')
-				->from('filecache')
-				->where($qb->expr()->orX(
-					// Hierarchical preview folder structure
-					$qb->expr()->like('path', $qb->createNamedParameter($this->previewRootPath . '%/%/%/%/%/%/%/%/%')),
-					// Legacy flat preview folder structure
-					$qb->expr()->like('path', $qb->createNamedParameter($this->previewRootPath . '%/%.%'))
-				))->andWhere(
-					$qb->expr()->eq('storage', $qb->createNamedParameter($this->rootFolder->getMountPoint()->getNumericStorageId()))
-				)
-				->hintShardKey('storage', $this->rootFolder->getMountPoint()->getNumericStorageId())
-				->setMaxResults(100);
-
-			$result = $qb->executeQuery();
-			$foundPreviews = $this->processQueryResult($result);
-
-			if (!$foundPreviews) {
-				break;
-			}
+		$storage = $this->rootFolder->getMountPoint()->getStorage();
+		if ($storage === null) {
+			$this->appConfig->setValueBool('core', 'previewMovedDone', true);
+			return;
+		}
 
-			// Stop if execution time is more than one hour.
-			if (time() - $startTime > 3600) {
-				return;
-			}
+		$cache = $storage->getCache();
+		$previewRootId = $cache->getId(rtrim($this->previewRootPath, '/'));
+		if ($previewRootId === -1) {
+			// No previews have ever been generated on this instance.
+			$this->appConfig->setValueBool('core', 'previewMovedDone', true);
+			return;
 		}
 
-		$this->appConfig->setValueBool('core', 'previewMovedDone', true);
-	}
+		$startTime = time();
 
-	private function processQueryResult(IResult $result): bool {
-		$foundPreview = false;
-		$fileIds = [];
-		$flatFileIds = [];
-		while ($row = $result->fetch()) {
-			$pathSplit = explode('/', $row['path']);
-			assert(count($pathSplit) >= 2);
-			$fileId = (int)$pathSplit[count($pathSplit) - 2];
-			if (count($pathSplit) === 11) {
-				// Hierarchical structure
-				if (!in_array($fileId, $fileIds)) {
-					$fileIds[] = $fileId;
-				}
-			} else {
-				// Flat structure
-				if (!in_array($fileId, $flatFileIds)) {
-					$flatFileIds[] = $fileId;
+		// Walk the preview folder tree via the `parent` column, which is indexed on
+		// every supported database platform.
+		//
+		// Depth from the preview root tells us which structure a leaf folder holds:
+		// - depth 1: legacy flat structure, e.g. preview/<fileid>/<size>.png
+		// - depth 8: hierarchical structure, e.g. preview/a/b/c/d/e/f/g/<fileid>/<size>.png
+		$foldersToVisit = [[$previewRootId, '', 0]];
+
+		while ($foldersToVisit !== []) {
+			[$folderId, $folderName, $depth] = array_pop($foldersToVisit);
+
+			$hasPreviewFiles = false;
+			foreach ($cache->getFolderContentsById($folderId) as $entry) {
+				if ($entry->getMimeType() === FileInfo::MIMETYPE_FOLDER) {
+					$foldersToVisit[] = [$entry->getId(), $entry->getName(), $depth + 1];
+				} else {
+					$hasPreviewFiles = true;
 				}
 			}
-			$foundPreview = true;
-		}
 
-		foreach ($fileIds as $fileId) {
-			try {
-				$this->migrationService->migrateFileId($fileId, flatPath: false);
-			} catch (\Exception $e) {
-				$this->logger->error('Failed to migrate preview with fileId: ' . $fileId . ' (hierarchical file structure)', [
-					'exception' => $e,
-				]);
+			if (!$hasPreviewFiles || !ctype_digit($folderName)) {
+				continue;
 			}
-		}
 
-		foreach ($flatFileIds as $fileId) {
 			try {
-				$this->migrationService->migrateFileId($fileId, flatPath: true);
+				$this->migrationService->migrateFileId((int)$folderName, flatPath: $depth === 1);
 			} catch (\Exception $e) {
-				$this->logger->error('Failed to migrate preview with fileId: ' . $fileId . ' (legacy file structure)', [
+				$this->logger->error('Failed to migrate preview with fileId: ' . $folderName, [
 					'exception' => $e,
 				]);
 			}
+
+			// Stop if execution time is more than one hour.
+			if (time() - $startTime > 3600) {
+				return;
+			}
 		}
-		return $foundPreview;
+
+		$this->appConfig->setValueBool('core', 'previewMovedDone', true);
 	}
 }
diff --git a/tests/lib/Preview/PreviewMigrationJobTest.php b/tests/lib/Preview/PreviewMigrationJobTest.php
index fe9cd968799..06108c954fb 100644
--- a/tests/lib/Preview/PreviewMigrationJobTest.php
+++ b/tests/lib/Preview/PreviewMigrationJobTest.php
@@ -119,7 +119,6 @@ class PreviewMigrationJobTest extends TestCase {
 			Server::get(ITimeFactory::class),
 			$this->appConfig,
 			$this->config,
-			Server::get(IDBConnection::class),
 			Server::get(IRootFolder::class),
 			new PreviewMigrationService(
 				$this->config,
@@ -157,7 +156,6 @@ class PreviewMigrationJobTest extends TestCase {
 			Server::get(ITimeFactory::class),
 			$this->appConfig,
 			$this->config,
-			Server::get(IDBConnection::class),
 			Server::get(IRootFolder::class),
 			new PreviewMigrationService(
 				$this->config,
@@ -203,7 +201,6 @@ class PreviewMigrationJobTest extends TestCase {
 			Server::get(ITimeFactory::class),
 			$this->appConfig,
 			$this->config,
-			Server::get(IDBConnection::class),
 			Server::get(IRootFolder::class),
 			new PreviewMigrationService(
 				$this->config,