Re: To log or not to log, that is the question.

On Mar 1, 12:21am, Malcolm Weallans wrote: > Subject: Re: To log or not to log, that is the question. > > >Would the only benefit be that you could do backups of the logs and > > therefore>have incremental backups since your last "big" backup? > > > Even an "unlogged" database writes DDL to the logs. And checkpoints > are > > logged. > > > But, if you don't log, your backups will be valid to only the last > > checkpoint. > > > Use buffered logging - it's fast and reasonably secure. > ^^^^^^^^^^^^^^^^^^ > I cannot believe what I am reading. REASONABLY SECURE!!! That's like > saying I've put a lock on my house and put the key under the mat. That's > reasonably secure. In the database world I don't believe nay of us can > accept being "reasonably secure". We need to be totally secure or > totally insecure. At least then we know where we stand! There is only > one use for BUFFERED LOGGING - to win benchmarks - nothing more!!! > > Malcolm Weallans Malcolm, I'd have to say that's a bit strong. Surely the issue here is cost of loss. If the cost of loss is less that the speed benefit then buffered logging has its place. I would probably agree that "reasonably secure" is no way to describe the choice as that assessment can only be done against the specific data that the database is using. I would hate to see someone recording the only copy of my medical records in a database with buffered logging as that could result in my death. Mind you some organisations could view this as an acceptable cost of doing business!! We do use buffered logging on a number of databases as the business view is that the speed advantage is worth the cost of loss. Generally this is because the information is available elsewhere and though costly to access the requirement to do so is so low that purchasing a box large enough to run unbuffered logging is not cost efficient. The trade off on buffered logging must be seen as how many transactions could you possibly lose and how much could you be damaged by their loss. Number of lost transactions depends on a number of factors such as how big you set your buffers, how often you checkpoint and your transaction rate, etc. The cost of loss depends on the information being stored and an estimate of the possibility of needing access to it. Cheers - Jim -- ----------------------------------------------------------------------------- Jim Gordon DHL Airways Inc. jgordon@us.dhl.com ----------------------------------------------------------------------------- My opinions are my own. They may vary with time but they remain mine!