RE: Question re: TRUNCATE ... REUSE STORAGE

From: Powell, Mark D <mark.powell_at_eds.com>
Date: Fri, 2 Jul 2004 12:31:56 -0400
Message-ID: <564DE4477544D411AD2C00508BDF0B6A2133DDCF@usahm018.exmi01.exch.eds.com>

Tanel your example shows that the that keep storage retained all 87 allocated blocks while drop storage kept only the first allocated = extent
which is what I said, so I guess you just objecting to my reference to = "top
of allocated space" which is getting just a little bit technical. I = would
hope the average reader would understand that means the HWM is reset to = look
like the table has just been allocated, i.e., no data.

HTH -- Mark D Powell --

-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org]On Behalf Of Tanel P=F5der 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 =20
      Highwater::  0x00406d72  ext#: 10     blk#: 1      ext size: 8    =

=20
#blocks in seg. hdr's freelists: 0 =20 #blocks below: 80 =20

Truncated with reuse storage:

Extent Header:: spare1: 0 spare2: 0 #extents: 11 = #blocks: 87

                  last map  0x00000000  #maps: 0      offset: 4128 =20
      Highwater::  0x00406d22  ext#: 0      blk#: 0      ext size: 7    =

=20
#blocks in seg. hdr's freelists: 0 =20 #blocks below: 0 =20

Truncated with drop storage:

Extent Header:: spare1: 0 spare2: 0 #extents: 1 = #blocks: 7

                  last map  0x00000000  #maps: 0      offset: 4128 =20
      Highwater::  0x00406d22  ext#: 0      blk#: 0      ext size: 7    =

=20
#blocks in seg. hdr's freelists: 0 =20 #blocks below: 0 =20

Tanel.

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Received on Fri Jul 02 2004 - 11:28:45 CDT