Re: Episode 2: the EntMgr Green Light!!

"Domenic G." <domenicg_at_hotmail.com> wrote in message news:c7e08a19.0311081901.60899479_at_posting.google.com...
> Guys,
>
> This is a bunch of BS. If your system is read-only most of the time,
> DSS, OLAP, then rebuilding your indexes after a huge load of data
> increases read performance -- don't tell me it doesn't. Smaller
> index, less I/O.

But is it significantly less? Might you not get a much more significant reduction in I/O by rebuilding the table first, and thus improving the clustering factor on your index? Who can say: you certainly can't, since you've not posted one quantifiable fact about how useful your index rebuilds are.

Point is, there are better things a proactive DBA can be doing with their time.

>
> Second, if the index starts growing again too quickly, the pctfree
> setting used on the rebuild was too low. The rebuild is not the
> culprit, you didn't use the correct setting.
>
> The base of the index is
> much better after a rebuild -- go write a b tree routine and you'll
> see for yourself.

In the first place, Oracle doesn't use "b-tree" indexes. It uses "b*trees".

In the second place, you can keep on stating these things as fact if you wish, but better people than you or I can prove to you that they are not immutable fact at all.

No-one is saying that indexes *never* need rebuilding. There are always exceptions. But they are exceptions.

But you clearly have a closed mind on the subject, so that's just fine and dandy. Rebuild away. Never let intelligent discourse get in the way of prejudice and blind faith, eh?

>
> Geez, you guys make a mountain out of a mole hill.

I think the motto of the day should be "if you live in a glass house, don't throw stones". It was you who claimed to be the experienced professional who knows all about these things. Other experienced professionals have pointed out to you a serious deficiency in your understanding of how Oracle's index structures work. Geez, you apparently didn't even know that indexes can be coalesced as well as tablespaces. In short, it was you that errected the mountain.

If you claim to be an experienced professional DBA, it would help gain you credibility if your experience was based on, er, experience, and not just on imbibing the myths promoted by Oracle Corporation's old training courses and documentation.

>Thank God I'm the
> only DBA in my shop. Next thing you'll say it's not a good idea to
> index FKs.

Now why would anyone say that? (Apart from the fact that Oracle Corporation does for 9i, but that's just a minor detail, I'm sure). It is testable and obvious that without indexes on foreign keys, the table locking issues are dreadful. Testable, provable, quantifiable.

If only you could do the same for the 'rebuild regularly' argument.

HJR Received on Sat Nov 08 2003 - 21:44:24 CST