MAX EXTENTS for a table

Question

Hello Guru's
I am working on oracle express 10 G on windows , This is my test machine. I am a beginner to oracle Dba activities,
Problem:
I want to restrict the size of a table (say max upto 400k)
My Approach:
1. I create a Tablepsace with uniform extent size (40K each)
2. I created a table in this tablespace with max extents 10 ( so that 40K * 10 = 400K)
SCOTT@xe>CREATE TABLESPACE TB
  2   DATAFILE 'F:\Oracle\oradata\XE\TB.DBF' SIZE 100M
  3   EXTENT MANAGEMENT LOCAL
  4   UNIFORM SIZE 40K
  5   ONLINE ;
Tablespace created.
SCOTT@xe>
SCOTT@xe>DROP USER G CASCADE ;
User dropped.
SCOTT@xe>CREATE USER G IDENTIFIED BY G DEFAULT TABLESPACE TB ;
User created.
SCOTT@xe>ALTER USER G QUOTA UNLIMITED ON TB;
User altered.
SCOTT@xe>GRANT CREATE SESSION , CREATE TABLE TO G;
Grant succeeded.
SCOTT@xe>CONNECT G/G@xe
Connected.
G@xe>CREATE TABLE t ( A number) TABLESPACE TB storage (minextents 1 maxextents 10);
Table created.
G@xe>SELECT SEGMENT_NAME, MIN_EXTENTS, MAX_EXTENTS , SEGMENT_TYPE, TABLESPACE_NAME, BLOCKS
  2  FROM USER_SEGMENTS  ;
SEGMENT_NAME                                                                      MIN_EXTENTS MAX_EXTENTS SEGMENT_TYPE       TABLESPACE_NAME                    BLOCKS
T                                                                                           1  2147483645 TABLE              TB                                      5
G@xe>Issue is:
I want the maximun extents that could be llocated to this table must be 10 , BUT from user_segments I could see MAX_EXTENTS = 2147483645 (default value).
When i pump data into this table MAX_EXTENTS exceeds 10 (i.e user Defined value)
I have no idea why this is the case;
Regards,

Answer 1

When creating a segment (Table/Index) in a Locally Managed Tablespace (created with "EXTENT MANAGEMENT LOCAL" and visible in DBA_TABLESPACES under EXTENT_MANAGEMENT), Oracle ignores the specification of MAXEXTENTS.
All segments in an LMT would default to MAXEXTENTS UNLIMITED (which really means 2 billion).
(DEFAULT STORAGE at the Tablespace level cannot be set if it is LOCAL AUTOALLOCATE or LOCAL UNIFORM)
See [The 10gR2 documentation on the STORAGE clause|http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/clauses009.htm#i997450]
In your 10gXE install you will not be able to create a DICTIONARY MANAGED Tablespace as the SYSTEM Tablespace itself is LOCALLY MANAGED.
If you want to limit the size of a table you could
a. Create a Tablespace with a set size for datafiles (ie, set AUTOEXTEND OFF for the datafiles)
b. Create the Table in that Tablespace
Edited by: Hemant K Chitale on Aug 18, 2009 3:31 PM