On Tue, 2006-10-03 at 18:29 -0700, Tomeh, Husam wrote: > >> * When any session updates the data that already in shared > buffer, > >>does Postgres synchronize the data both disk and shared buffers area > >> immediately ? > > Not necessarily true. When a block is modified in the shared buffers, > the modified block is written to the Postgres WAL log. A periodic DB > checkpoint is performed to flush the modified blocks in the shared > buffers to the data files. Postgres 8.0 and beyond have a process called bgwriter that continually flushes dirty buffers to disk, to minimize the work that needs to be done at checkpoint time.
