On 15 Sep 2009, at 20:30, Chris Anderson wrote:
On Tue, Sep 15, 2009 at 10:22 AM, Jan Lehnardt <[email protected]> wrote:
On 15 Sep 2009, at 19:09, [email protected] wrote:
Author: jchris
Date: Tue Sep 15 17:09:22 2009
New Revision: 815404
URL: http://svn.apache.org/viewvc?rev=815404&view=rev
Log:
changed default for 0.10 to delayed_commits = true for fast out of
box
experience
Chris, please discuss this first on d...@.
Sorry about that - just having a strong gut reaction to the potential
of releasing 0.10 that's too slow to use.
Good thing is that this commit got everyone talking on IRC.
The basic tradeoff here is between safety and speed. With a simple
benchmark on my Mac laptop (OSX 10.5) delayed_commits gives ~230
writes/second while we only get about 5/sec with the slow safe option.
I think 5 writes/second is too slow to be useful, so it doesn't matter
how safe it is.
I think we need to define use-cases a bit more clearly and then try to
determine how much safety we can and want to guarantee. I'd like to
avoid situations where we send a Created 201 response when that
doc is still in limbo and CouchDB could do extra work to make sure
it is on disk.
I especially don't want to enable delayed commits by default for simple
speed-freak reasons. CouchDB could easily detect long running fsync()s
and send a log entry about enabling delayed commits. Proper
documentation
& release notes will help too. Finally, there will always be people
claiming
CouchDB has whatever properties (slow, fast, green) they see fit*.
If we want to bill CouchDB as everybody's personal database, we better
keep that personal data safe :)
Cheers
Jan
--
* See Postgres.
