RE: Question re: TRUNCATE ... REUSE STORAGE

From: Mark W. Farnham <mwf_at_rsiz.com>
Date: Fri, 2 Jul 2004 12:50:47 -0400
Message-ID: <KNEIIDHFLNJDHOOCFCDKOELIEPAA.mwf@rsiz.com>

I think you're in violent AGREEMENT.

However, the lingo "top of allocated storage" in the context of a high water mark is truly confusing, since in this context "top" is as low as the high water mark can go. Ugh.

mwf

-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org]On Behalf Of Tanel Põder Sent: Friday, July 02, 2004 12:05 PM
To: oracle-l_at_freelists.org
Subject: Re: Question re: TRUNCATE ... REUSE STORAGE

> No, the high water mark is reset to the top of the allocated space. The
> option means the allocated space remains allocated to the object. "Drop
Mark, the HWM is reset to point to first block after segment header when you truncate with keep storage (sometimes referred as HWM is reset to zero). Just the extent map is kept.

A table header block with some rows:

  Extent Header:: spare1: 0      spare2: 0      #extents: 11     #blocks: 87
                  last map  0x00000000  #maps: 0      offset: 4128
      Highwater::  0x00406d72  ext#: 10     blk#: 1      ext size: 8

#blocks in seg. hdr's freelists: 0
#blocks below: 80

Truncated with reuse storage:

  Extent Header:: spare1: 0      spare2: 0      #extents: 11     #blocks: 87
                  last map  0x00000000  #maps: 0      offset: 4128
      Highwater::  0x00406d22  ext#: 0      blk#: 0      ext size: 7

#blocks in seg. hdr's freelists: 0
#blocks below: 0

Truncated with drop storage:

  Extent Header:: spare1: 0      spare2: 0      #extents: 1      #blocks: 7
                  last map  0x00000000  #maps: 0      offset: 4128
      Highwater::  0x00406d22  ext#: 0      blk#: 0      ext size: 7

#blocks in seg. hdr's freelists: 0
#blocks below: 0

Tanel.

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Received on Fri Jul 02 2004 - 11:47:18 CDT