Rollback segment
The following testing script intends to create the smallest rollback segments. Why it ends up creating 64k rollback segments?
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SQL> DROP ROLLBACK SEGMENT rollseg01;
Rollback segment dropped.
SQL>
SQL> drop tablespace rbs2 including contents;
Tablespace dropped.
SQL>
SQL> Create tablespace RBS2
2 DataFile
3 '/export/home/u01/oradata/koya/rbs02.dbf' reuse
4 -- Size 5M AutoExtend On Next 640 Maxsize 100M
5 Default Storage (
6 Initial 8k
7 Next 8k
8 Minextents 2
9 Maxextents 4096
10 Pctincrease 0
11 )
12 ONLINE
13 PERMANENT
14 /
Tablespace created.
SQL>
SQL> CREATE ROLLBACK SEGMENT rollseg01
2 TABLESPACE RBS2
3 STORAGE ( INITIAL 1k
4 NEXT 1k
5 MINEXTENTS 2
6 MAXEXTENTS 5
7 );
Rollback segment created.
SQL>
SQL> alter rollback segment rollseg01 online;
Rollback segment altered.
SQL>
SQL> SELECT segment_name, tablespace_name, bytes, blocks, extents
2 FROM sys.dba_segments
3 WHERE segment_name = 'ROLLSEG01'
4 /
SEGMENT_NAME TABLESPACE_NAME BYTES BLOCKS EXTENTS
------------------------------ ------------------------------ ---------- ---------- ----------
ROLLSEG01 RBS2 65536 8 2
1 row selected.
SQL>
