On Tue, Nov 15, 2011 at 8:48 PM, Greg Smith <greg@2ndquadrant.com> wrote:
> When you turn off the synchronous_commit parameter in the postgresql.conf,
> the database will stop asking the filesystem to ensure things are on disk
> this way. You can lose some data in the event of a crash, but things will
> be faster.
An important bit here is that unlike turning fsync off, your
filesystem and database will still be coherent after a power loss
event. so it's semi-safe, in that you won't be recovering your whole
db in the event of a power loss / crash.
> unlikely to be caused by the ext4 changes. In just about every other way
> but commit performance, ext4 is faster than most other filesystems.
On fast hardware, ext4 is a good performer overall and comes within a
pretty close reach of the other fast file systems. And since it's in
the mainline kernel and used by lots of distros, it gets a lot of real
world testing and bug fixing to boot. I'm with you, if there's a real
performance problem I'd suspect something other than ext4.