Re: Q:Table Fragmentation. How do I reduce it?

Matthias Gresz wrote:
>
> On Tue, 17 Mar 1998 17:10:45 +0800, Connor McDonald <mcdonald.connor.cs_at_bhp.com.au> wrote:
>
> Hi Connor,
> why fragmentation does not affect performance? Everybody, every book claims that fragmantation is a performance penalty.
>

No, not everybody. The Oracle Performance Group advises that most reorgs are not worth the time and risk. They advise us to use proper NEXT, PCTFREE and PCTUSED to prevent problems.

> >Rao Uppuluri wrote:
> >>
> >> Hi all
> >>
> >> Setup: Oracle 7.3.2.3 on HP-UX 10.20
> >>
> >> I have a table(s) with lot of extents allocated to it. These extents are
> >> small extents. The extents allocated are not all next to each other.
> >> Some are but not all. If I drop the table and recreate it, do I get a
> >> lot of "free space fragmentation"? How do I reduce the fragmentation of
> >> the table? Do I have to export and import the whole tablespace?? ( I have
> >> many of these tables with lot of extents allocated to them in the tablespace)
> >>
> >> Thanx in ADvance
> >>
> >> Rao Uppuluri
> >> (uppuluri_at_XidtX.net -- Please remove X's)
> >
> >Also worthy of note that in a normal (ie multi-user) environment then as
> >a general rule, lots of extents will NOT affect performance. The
> >popular belief that the performance of one extent is always better than
> >many is a myth...
> >
> >This is not to say the exp/imp will not assist. Unloading and reloading
> >the data has many benefits in terms of better packing the rows etc
> >etc...But exp compress=y OR exp compress=n will give you the same
> >benefits...
> >--
> >==========================================
> >Connor McDonald
> >BHP Information Technology
> >Perth, Western Australia
> >"These views mine not BHP..etc etc"
> >
> >"The only difference between me and a madman is that I am not mad."
>
> --
>
> Regards
>
> Matthias Gresz :-)
>
> GreMa_at_T-online.de
  Received on Tue Mar 17 1998 - 00:00:00 CST