diff --git a/runtime/lib/piwigo-db-check.php b/runtime/lib/piwigo-db-check.php
new file mode 100644
index 0000000..2e3d061
--- /dev/null
+++ b/runtime/lib/piwigo-db-check.php
@@ -0,0 +1,53 @@
+<?php
+declare(strict_types=1);
+
+if ($argc !== 3) {
+    fwrite(STDERR, "Usage: piwigo-db-check.php MAP_FILE PIWIGO_ROOT\n");
+    exit(2);
+}
+
+$mapFile = $argv[1];
+$piwigoRoot = rtrim($argv[2], '/') . '/';
+$databaseConfig = $piwigoRoot . 'local/config/database.inc.php';
+
+if (!is_file($databaseConfig)) {
+    exit(1);
+}
+
+$mapping = json_decode((string) file_get_contents($mapFile), true, 512, JSON_THROW_ON_ERROR);
+$expected = [];
+foreach ($mapping as $source => $target) {
+    if (str_starts_with((string) $source, 'share:') && !str_contains((string) $source, '/')) {
+        $expected[] = basename((string) $target);
+    }
+}
+if ($expected === []) {
+    exit(1);
+}
+
+$conf = [];
+$prefixeTable = '';
+require $databaseConfig;
+
+$database = new mysqli(
+    (string) $conf['db_host'],
+    (string) $conf['db_user'],
+    (string) $conf['db_password'],
+    (string) $conf['db_base']
+);
+$database->set_charset('utf8mb4');
+$table = $database->real_escape_string((string) $prefixeTable) . 'categories';
+$result = $database->query(
+    'SELECT dir FROM `' . $table . '` WHERE site_id = 1 AND dir IS NOT NULL'
+);
+$existing = [];
+while ($row = $result->fetch_assoc()) {
+    $existing[(string) $row['dir']] = true;
+}
+
+foreach ($expected as $directory) {
+    if (!isset($existing[$directory])) {
+        exit(1);
+    }
+}
+exit(0);