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  • From: Frediano Ziglio <freddyz77 AT tin.it>
  • To: TDS Development Group <freetds AT franklin.oit.unc.edu>
  • Subject: RE: Problem with Sybase
  • Date: 25 Oct 2002 21:23:07 +0200


Il ven, 2002-10-25 alle 17:38, Lowden, James K ha scritto:
> > From: ZIGLIO Frediano [mailto:Frediano.Ziglio AT vodafoneomnitel.it]
> > Sent: October 25, 2002 4:16 AM
> >
> > I tried with command
> >
> > 1> dump tran tempdb to 'output.txt'
> >
> > But it reply with strange error...
>
> Frediano,
>
> I think "dump tran with no_log" is your friend. That's the old syntax and
> should still work.
>

I tried with "dump tran tempdb with no_log" but I got still

The transaction log in database tempdb is almost full. Your transaction
is being suspended until space is made available in the log.

After a bit of time I think Sybase extend log and continue... program
finish with success... and subsys file under /opt/sybase-11.9.2 became
bigger and bigger (yesterday was 61MB, now 62).

> Sybase's design uses a write-ahead log. Your query is written to the
> transaction log first, then applied to the data, then marked as "done" in
> the log. Only then is the transaction considered "committed". Not until
> then can it be removed from the log.
>
> Microsoft moved the log out of the database and put it in the filesystem,
> but its role and purpose were unchanged.
>
> This design allows the server to "know" the state of the database at any
> point in time. After a power failure, the system can examine the log,
> compare it to the tables, and "roll forward" any transaction that was
> written to the log but unapplied. Conversely, any partially written log
> records can be discarded. (BTW, I think this is the most important feature
> separating proprietary databases from free ones.)
>
> The log continues to grow until it is "truncated", meaning that committed
> records are removed. If the truncation operation saves the records to a
> file, they can be used later as part of an incremental restore operation.
> We have many such "warm standby" machines here: they have a copy of the
> production database, and periodically (say, every 10 minutes) the production
> log is truncated and applied to the standby. Data loss is thus constrained
> to the truncation window. For more information, rtfm; look for "Checkpoints
> and the Active Portion of the Log".
>
> In your case, you don't need a backup, you just want your space back. That
> was my slogan when I was doing sysadmin work, "The only good disk is an
> empty disk." Empty disks are quick to scan, quick to back up, are never
> full. No one ever loses a file on them. They're ideal, wouldn't you say?
> But I digress. Again.
>
> In such cases, where you just want to minimize the size of the tranlog and
> not worry about backups, the "trunc. log on chkpt." database option (cf.
> "Setting Database Options") is very handy. Every minute or so the system
> will inspect the log and automatically remove committed transactions.
>

freddy77






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