"After a checkpoint has been made and the log flushed, the checkpoint's position is saved in the file pg_control. Therefore, at the start of recovery, the server first reads pg_control and then the checkpoint record; then it performs the REDO operation by scanning forward from the log position indicated in the checkpoint record. Because the entire content of data pages is saved in the log on the first page modification after a checkpoint (assuming full_page_writes is not disabled), all pages changed since the checkpoint will be restored to a consistent state."
Hi, yes I know that, it's what I meant in my point 3). As it says first "the checkpoint's position (NOT the record)is saved in the file pg_control" then I had some doubt.