MAGETWO-43906: Long database prefix length breaks setup

- fixed

Author: Ivan Gavryshko

setup/src/Magento/Setup/Validator/DbValidator.php

@@ -15,6 +15,9 @@
  */
 class DbValidator
 {
+
+    const DB_PREFIX_LENGTH = 10;
+
     /**
      * DB connection factory
      *
@@ -47,6 +50,12 @@ public function checkDatabaseTablePrefix($prefix)
             throw new \InvalidArgumentException('Please correct the table prefix format.');
         }
 
+        if (strlen($prefix) > self::DB_PREFIX_LENGTH) {
+            throw new \InvalidArgumentException(
+                'Table prefix length can\'t be more then ' . self::DB_PREFIX_LENGTH . ' characters.'
+            );
+        }
+
         return true;
     }