BDB corrupt

[Jeremy Chadwick]

On Tue, May 13, 2008 at 03:44:06PM +0400, Anthony Pankov wrote:
> If concurrency is the only problem then:
> 1. ?an data corruption be avoided? Or this is impossible?
> 2. How?

Use Sleepycat/Oracle DB instead?  The libc DB1.x, despite being
"mature", really should be deprecated in some manner.

I'm sure there are others I've forgotten, but the only thing I can think
of in the base system which relies on DB1.x is sendmail (which IMHO
should really be removed from the base system and replaced with a small
standalone mailer -- but that's been discussed in a previous thread in
the past).  Even "simple" ports like postgrey pull in db41, even though
they could technically "work fine" with DB1.x.

> If all BDB readers would use O_SHLOCK and all writers O_EXLOCK is it
> guarantee for data integrity?

The corruption I've seen in the past results in DB operations failing
for no particular reason ("what do you mean those are all the records?
No!  I just inserted a bunch more!").  It turns out some of the data in
the actual .db file is corrupt -- even when locking is used everywhere.
It's as if the code has some weird bug where it'll write bogus data to
the file for some reason.

I'll ask you this: is there some particular reason you can't just write
to a file yourself, using your own/documented file format?  Why does DB
have to be used?

-- 
| Jeremy Chadwick                                jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |