On Tue, Nov 12, 2013 at 6:57 AM, Jayadevan M <maymala.jayade...@gmail.com>wrote:
> Hi, > What are the real differences between the bgwriter and checkpointer > process? Both of them write data from the buffer to the data files, right? > Is it just a matter of 'when' they write? > Regards, > Jayadevan > Expect some corrections by others on my understanding described below. AFAIK, they share the load of writing dirty-buffers to disk, though they are defined to serve different purpose. Basically, background writer process sole function is to write "dirty" shared buffers to disk and evict those pages from shared buffer pool. Whereas checkpoint, arrives to write all dirty data pages in shared_buffers to disk only when checkpoint_timeout or when all checkpoint_segments are filled, whichever comes first. However, BG Writer (Writer Process) will be continuously trickle out dirty pages to disk so that by the time checkpoint arrives there will be left only with f ew dirty pages, instead of having lots of dirty pages to carry out by i tself alone and cause I/O loaded . --- Regards, Raghavendra
