This appears to be a table in a dictionary managed tablespace (DMT). Is
there a reason that you are not using locally managed tablespaces (LMTs)
everywhere? That would eliminate the possibility of fragmentation in
addition to making it much more efficient to allocate and manage
extents.
That said, I'm not sure that this has anything to do with a table "not
responding well". I'm not sure what symptoms, exactly, you are seeing,
but it would be unlikely that the DBA_EXTENTS table would give you much
information (unless there has been a lot of investigation from the
symptoms that lead you to suspect a problem with extent allocation.
Justin Cave
Distributed Database Consulting, Inc.
http://www.ddbcinc.com/askDDBC
-----Original Message-----
From: Mathews Ansamma
[mailto:oracledba-ezmlmshield-x17006714.[Email address protected]
Sent: Thursday, October 27, 2005 1:01 PM
To: LazyDBA Discussion
Subject: Doubts about EXTENT allocation
Dear DBAs,
I have a table that is not responding well. I liiked at the storage
parameters and found the following.
Select min_extents, initial_extent, next_extent, max_extents,
extents,PCT_INCEASE from dba_segments where segment_name='MY TABLE';
MIN_EXTENTS INITIAL_EXTENT NEXT_EXTENT MAX_EXTENTS EXTENTS
PCT_INCREASE
1 65536 8600518656 505
31 50
Then I looked at the DBA_EXTENTS to get more info.
select extent_id, bytes from DBA_EXTENTS where segment_name='ID_LOGON'
order
by extent_id;
0 81920
1 40960
2 81920
3 122880
4 163840
5 245760
6 368640
7 532480
8 778240
9 1146880
10 1720320
11 2580480
12 3891200
13 5816320
14 8724480
15 13107200
16 19660800
17 29491200
18 44195840
19 66314240
20 99450880
21 149176320
22 223723520
23 335585280
24 503365632
25 755048448
26 1132576768
27 1698865152
28 2548301824
29 3822477312
30 5733679104
I assume that the extent_id 0 is for oracle internal work. extent ID 1&2
are
multiples of my block size (8192 *5 and 8192 * 10) .
Then it seems to be going per the PCT _INCREASE factor. My question is
what
is the effect of setting next_extent in the
storage clause? Does oracle allocates the minimun of the value by
PCT_INCREASE and next_extent ?
Appreciate your advice.
Thanks,
Ancy
--------
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