On Mon, Aug 26, 2013 at 4:57 AM, 高健 <luckyjackgao@xxxxxxxxx> wrote: > But why "writes the entire content of each disk page to WAL "? > The documentation states that: "The row-level change data normally stored in WAL will not be enough to completely restore such a page during post-crash recovery.". I guess that a mixed page (i.e., a page that contains old and new data) cannot be safely recovered with deltas, so you need to have a "clean" page image to which start recovery. Someone with more internal knowledge can comment on this. Luca -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
