Re: What is against autoextending datafiles? (was: autoextend = ???

Connor McDonald wrote:
>
> Howard J. Rogers wrote:
> >
> > "Frank van Bortel" <fbortel_at_home.nl> wrote in message
> > news:3ACB844F.2CC41C50_at_home.nl...
> > >
> > > Please elaborate as to why (proof, please!) autoextending datafiles
> > > is a bad idea?
> > > (In a highly tuned env, I agree - for civil servants, I tend to use it)
> > >
> >
> > When do you think the data files will want to take advantage of its ability
> > to autoextend?
> >
> > 1. When it's run out of space
> > 2. When someone is doing a piece of DML which requires more space
> >
> > So the autoextension takes place precisely when you *don't* want it to
> > happen... at exactly the moment when your User is hoping to do a quick
> > insert and get on with something more useful to do. Instead, he has to sit
> > there whilst a full-blown conversation takes place in the data dictionary
> > along the lines of "I'd like to do an Insert please." "Can't -no free
> > space". "Well, can you autoextend?" "Don't know -I'll just check <pause>..
> > yes, I can". "Well, can you do so please?" "How much by?" "Oh, I'm a
> > 50K-extent segment, so 50K will do fine" "OK. Hang on. <pause whilst disk is
> > visited> OK you may proceed". "Cheers."
> >

Ok, let's have your version, then (and I happily cut'n paste:) "I'd like to do an Insert please." "Can't -no free space". "Well, can you autoextend?" "Don't know -I'll just check <pause>..  No, I can't". "Well,I'll throw an error then" (error gets thrown)
Now the user (Jim) get's in:
"hey, want's that? John, come and have a look, is that normal?" <pause while John reluctantly puts his coffemug down, and strolls over to Jim's desk:> "Hmmm, nope, don't think so.... dunno... works for me all the time. Did you press the right clikcteclick?" Jim:"Dunno - think so. Will try again"
(OK - read once more from the beginning) Jim:"He, John, it still not running." John:"Better call Howard, then, he'll
know what to do". Howard is off to lunch, but gets back to his desk and fixes
the problem in notime. Phones back immedeately. Only 15 minutes lost.

Would that be more efficient?
> >
> > But if it is going to be used, it's crucial that there is a 'NEXT' clause
> > used, so that the thing doesn't continually try and grab tiny bits of extra
> > disk space. Instead it should acquire juicy great chunks each time (I seem
> > to recall a 'NEXT 100M' every time I went on holiday). And I'd not abandon
> > the entire disk to said files, so a 'MAXSIZE' clause is pretty much a
> > requirement.

Strike the pretty - it *is* a requirement, not only to keep from filling up volumes,
but also to avoid 2/4GB barries being crossed.
>
> Other than that, generally I reckon autoextend is like holding a flag
> saying "I don't know whats happening on my database"...

Connor, are you still coalescing by hand? Don't you use locally managed tablespaces?
No you don't - you use the options that come along. That does in no way mean you
don't know what's going on. It's just the same for autoextending datafiles.
Which have crummy defaults, like so much in Oracle's RDBMS. Which has to be used wisely, like so much in Oracle's RDBMS. And with caution, like so much in
Oracle's RDBMS.

-- 
Gtrz,

Frank van Bortel