Re: Segment management auto clause

"Howard J. Rogers" <howardjr2000_at_yahoo.com.au> wrote in message news:1Awwa.34460$1s1.499663_at_newsfeeds.bigpond.com...
>
> "Richard Foote" <richard.foote_at_bigpond.com> wrote in message
> news:zJrwa.34254$1s1.498229_at_newsfeeds.bigpond.com...
> > "Howard J. Rogers" <howardjr2000_at_yahoo.com.au> wrote in message
> > news:NKawa.33877$1s1.492365_at_newsfeeds.bigpond.com...
> > > The test results I got were posted right here not so very long ago
(late
> > > last year, I believe).
> >
> > Hi Howard,
> >
> > I've looked back and I think you're refering to the thread "What space
of
> a
> > Oracle Block is being used" which goes back to last August (boy, does
time
> > fly !!)
> >
> > Reading through it all again, a few points I would make.
> >
> > Firstly, the results are based only on a couple of benchmarky sort of
> tests
> > and certainly can't be classified as conclusive proof (as can't my
testing
> > although I've been playing with all this for quite a while).
>
> Excuse me, Richard: those particular posts might have been based on a
couple
> of "benchmarky" tests, but I wouldn't stick to a position if extensive
> subsequent and rather less "benchmarky" tests hadn't confirmed me in my
> views.

Hi Howard,

Point taken.

But you do admit to having taken to a position rather strongly that "you would be one mad lunatic" if you would ever use ASSM, except with RAC or heavily inserted situations (like you again suggested to the OP) . I don't ever recalling you mentioning that ASSM may be useful in other scenarios.

I guess the point I would make is that it may not be so black and white ...

>
> >
> > Secondly, there was some debate regarding each extent requiring it's own
> set
> > of bitmap blocks. This is incorrect. One bitmap block can map to many
> > extents and indeed as an object grows, Oracle assigns more bitmaps
within
> a
> > bitmap block. Basically the ratio of bitmap blocks is based on a sliding
> > decreasing proportion to the number of blocks (not extents) in a segment
> > (show anyone interested a few block dumps if you like)
>
> Don't need to to me at any rate. It isn't one-bitmap-for-one-extent, I
don't
> think I suggested with any absolute certainty that it *was* one-for-one,
but
> I haven't been saying anything of late other than that it starts
> one-for-one.

But that's incorrect.

If the extents are tiny, then one first level bitmap blocks could span several extents.

If the extents are large, you could have many bitmap blocks ...

Even at the start ...

Cheers

Richard Received on Wed May 14 2003 - 16:24:20 CDT