On Tue, Oct 8, 2013 at 1:54 AM, 高健 <luckyjack...@gmail.com> wrote:
> Hello: > > Sorry for disturbing: > > I have one question about checkponint . That is : can checkpoint be > parallel? > PostgreSQL does not currently implement it that way. And it is hard to see what the benefit would be of doing so. But it should be theoretically possible. > It is said that checkpoint will be activated according to either > conditions: > > 1)After last checkpoint, checkpoint_timeout seconds passed. > After the *start* of the last checkpoint. Provided that the last checkpoint has finished. > 2)When shared_buffers memory above checkpoint_segments size is filled > with data. > It is not shared_buffers that is measured, but the WAL files themselves (which effectively means wal_buffers usage) that is measured. > My experience is that : > > There is only one checkpoint process there and works, and even when there > are many data created during transactions, > > There will also be only one checkpoint process deal with it > > (maybe background writer or some other server process will deal it)? > The background writer and ordinary backends might write data (for their own reasons) that the checkpointer would have otherwise needed to write anyway. Cheers, Jeff
