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Re: Mass Deletions From Tables

From: Stephen Ferracioli <sferraci_at_pioneer-usa.com>
Date: Wed, 07 Aug 2002 21:30:53 GMT
Message-ID: <gkg49.798$UN5.58177778@newssvr13.news.prodigy.com>

"Sybrand Bakker" <postbus_at_sybrandb.demon.nl> wrote in message news:mc33lu490s5bqlk20cv500mohaklu1lv6m_at_4ax.com...
> On Wed, 07 Aug 2002 18:34:14 GMT, "Stephen Ferracioli"
> <sferraci_at_pioneer-usa.com> wrote:
>
> >My company is using SAP Business Warehouse (BW). BW allows us modify update rules and to
re-load
> >existing data transparent to the user. When the loads are complete, the previous packets of
> >data are deleted. My question is this:
> >
> >When a table approx 500Mb in size grows by another 500Mb and then the first 500 Mb is
deleted,
> >will Oracle reclaim the space that is now no longer in use or do I need to reorganize (i.e.
> >export/import) the table to get that space back?
> >
> >Thanks
> >
> >Stephen Ferracioli
> >Database Administrator
> >Pioneer Electronics
> >
>
> Depends whether the blocks from which data was deleted fall below
> pctused. You are deleting the *logically* first 500 Mb, do you? You
> can't guarantee they are *physically* the first 500 Mb.

I'm pretty sure that I am deleting the *physically* first 500 Mb. I am loading a replacement set of data. BW manages data by packets. The new packets are not available to the user until I delete the old packets and activate the new ones. The data is physically stored in the sequence it was sorted. The "star schema" is a *logical* representation of the data in BW. The foreign keys of the star schema do not have any bearing on the sequence of data in the fact table. SAP uses a relational dbms but the data is accessed using a network of pointers. Really wild stuff.

>
> Usually you are left with holes everywhere and the only solution is to
> reorganise.
>
> Hth
>
>
> Sybrand Bakker, Senior Oracle DBA
>
> To reply remove -verwijderdit from my e-mail address
Received on Wed Aug 07 2002 - 16:30:53 CDT

Original text of this message

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