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SubjectRe: [big performances boost for DataBases] Re: cache killer memory death test - 2.0 vs 2.2 vs arca - programs inside
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Andrea Arcangeli <andrea@e-mind.com> writes:

> On 25 Apr 1999, Harvey J. Stein wrote:
> >
> >Given that I'm just building the file & exiting, if the kernel behaves
> >well, then I don't see any reason then to do any gdbm_sync calls at
> >all. Closing the dbase does an fsync & forces everything to disk
> >anyway. Why do you think the additional gdbm_sync calls are a good
> >idea?
>
> Closing the DB doesn't do a fsync. That's the whole point. If you do that
> you'll get data integrity on disk ASAP (instead you won't get better data
> integrity doing sync in the middle of the proggy if you write to disk
> after the sync, that's also one of the reason the current buffer.c is
> broken according to me). But if you need to run the dbase executables many
> times you can also drop the gdbm_sync before exit.

Yes it does - I checked the source code before making the claim:

From gdbm-1.7.3/gdbmclose.c:

void
gdbm_close (dbf)
gdbm_file_info *dbf;
{
register int index; /* For freeing the bucket cache. */
/* Make sure the database is all on disk. */
if (dbf->read_write == GDBM_WRITER)
fsync (dbf->desc);
<snip>

--
Harvey J. Stein
BFM Financial Research
hjstein@bfr.co.il

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