Re: log question

"John" <j_barbe_at_hotmail.com> wrote in message news:8bc78dd8.0105290322.10d28643_at_posting.google.com...
> > If you think you can really do without redolog files (which is just a
 Career
> > Limiting Move), set the hidden init.ora parameter _nologging to true.
> > Of course, if anything does go wrong, you can't recover your database
 and
> > you are on your own.
>
>
> WOW
Yeah, wow that this is third post about this tonight! What is this? Nologging season?

> what is this parameter?

Well, there's a slight error in the original post as excerpted above, because the real parameter (at least in 8i) is called "_disable_logging". It's a 'hidden parameter' (all parameters that start with an underscore are so-called). That means its use is unsupported, and likely to be problematical.

> Does it really unables the redo log?

Yes, it totally switches off the generation of all redo across the entire database.

> DO people really use this?

Yes, but extremely carefully, and mindful of the warning that the database can be entirely lost if anything goes wrong whilst it is in effect. Just been dealing with someone that loads around 10,000,000 rows at the end of the month into a data warehouse... they take a cold, complete backup first, and then startup having switched on this parameter. The load runs much, much faster than it otherwise would do. Then they shutdown, take a fresh cold, complete backup, and re-start the Instance having disabled the parameter. They understand that if there was an Instance failure during the load, they must revert to the first backup in its entirety, and don't even think about rescuing the mess of the database that is left after the partial load.

Bear in mind that backing up a database of that size is not a trivial operation, so it is open to question whether they actually save any time doing things this way. But they seem to like it, and swear they still win out in the end.

My worry is that one day they will start up after the load and accidentally forget to disable the parameter....

So: It has its uses. I'd never recommend it.

Regards
HJR Received on Tue May 29 2001 - 08:05:23 CDT