Re: svn commit: r36749 - trunk/subversion/libsvn_subr

On Tue, Mar 24, 2009 at 06:03:48AM -0700, Bert Huijben wrote:
> Author: rhuijben
> Date: Tue Mar 24 06:03:48 2009
> New Revision: 36749
>
> Log:
> * subversion/libsvn_subr/sqlite.c
> (svn_sqlite__open): Switch sqlite synchronization off to make Sqlite
> performance workable on systems implementing full synchronization.
> Even with synchronization disabled Sqlite guarantees transactions over
> application crashes above the WC.1.0 level; and yournaling filesystems
> provide most of the other safety functions without this penalty.

What does this mean for systems that don't have journalling file systems?
Do they lose those other safety functions? What safety functions are lost
exactly?

What is "WC.1.0 level"? What thing can have or reach this level?
And is it something we can define or is it something defined internally
by sqlite?

(I don't know much about sqlite so please excuse my ignorance).

If this change can cause problems on platforms lacking features such
as journaling file systems, I'd rather make this a configurable setting
controlled by the user, with default set to safety, not performance.
At least in the stock svn client.

> Added ### comment to help reviewing this decision before releasing 1.7.0.

> + /* ### Switch to normal when transactions
> + resolves the major performance penalty.*/

Can you make this comment more clear? The log message indicates the
comment was addressing some controversial issue, but the comment itself
is not very clear as to what this controversial issue is. (And it also
has a grammatical error.) Maybe I don't understand the comment because
I don't know the answers to my questions above?

Thanks,
Stefan
Received on 2009-03-24 14:25:51 CET