I am using SQLite 3 with PHP 7 + NGINX. It appears the write-ahead log is supposed to write to temporary files when the database is locked, to allow for concurrency. However, when I try to write to the database simultaneously, I am greeted with the "database is locked" error. No temporary files are created. Am I supposed to enable the write-ahead log? Is it disabled by default? If so, how do I enable it Thanks!