Kevin Goess wrote > Can anybody help me understand what these statistics are suggesting, > what's > actually going on on this box/in postgresql? What is it writing to disk, > and why? Is it just writing out new/changed rows, or what? Not a clue on the statistics but most likely you are seeing checkpoint activity. At a simplified level all changes to the database are first persisted to disk using WAL (write-ahead-logs). The changes are written to disk, into WAL files, during commit via fsync. The original data files are not affected immediately thus improving performance at the time of commit by instead risking a prolonged delay in situations where an unclean shutdown occurs. However, at some point the WAL files need to be removed and the physical table files updated. This occurs during a checkpoint. A checkpoint basically causes the on-disk files to become baselined to the current reality so that only subsequent WAL files need be applied. There is considerably more to this whole concept than I can go into off the top of my head but in addition to looking at just I/O it would help to look, simultaneously, at what processes are active. HTH David J. -- View this message in context: http://postgresql.1045698.n5.nabble.com/pgpgout-s-without-swapping-what-does-it-mean-tp5796346p5796355.html Sent from the PostgreSQL - general mailing list archive at Nabble.com. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
