Logging/nologging

Question

what is the usage of creating table with nologging, by default logging while creating table .
kindly temme the solution

Answer 1

Morgan, Please check the following:
a.     log_mode from v$database
b.     Is the database configured to be in force logging?
c.     Is the tablespace on which the table reside, configured to be in force logging?
In addition, here is the complete example (including ctas), using Tom Kyte mystats script:
SQL> create table nolog nologging as
  2  select cast(' ' as char(2000)) as str
  3  from dual connect by level <=1000;
Table created.
SQL> @c:\mystats "redo size"
NAME                                  VALUE
redo size                         8,662,356
SQL> create table yeslog logging as
  2  select cast(' ' as char(2000)) as str
  3  from dual connect by level <=1000;
Table created.
SQL> @c:\mystats2
NAME                                    V DIFF
redo size                        11466672        2,804,316Using the nologging in the ctas we avoided from generating a 2,804,316 of redo!
another one:
SQL> alter table nolog move;
Table altered.
SQL>  @c:\mystats "redo size"
NAME                                  VALUE
redo size                        11,530,252
SQL> alter table yeslog move;
Table altered.
SQL> @c:\mystats2
NAME                                    V DIFF
redo size                        14340152        2,809,900Using the nologging in the "alter table move" we avoided from generating a 2,809,900 of redo!
and here is another one:
SQL> create index nolog_a1 on nolog(str) nologging;
Index created.
SQL> @c:\mystats "redo size"
NAME                                  VALUE
redo size                        14,409,096
SQL> create index yeslog_a1 on yeslog(str) logging;
Index created.
SQL>  @c:\mystats2
NAME                                    V DIFF
redo size                        18141176        3,732,080and here is another one:
SQL> alter index nolog_a1 rebuild nologging;
Index altered.
SQL> @c:\mystats "redo size"
NAME                                  VALUE
redo size                        18,219,204
SQL> alter index yeslog_a1 rebuild logging;
Index altered.
SQL> @c:\mystats2
NAME                                    V DIFF
redo size                        21959552        3,740,348Don't forget to backup your objects, after all this nologging actions!
Amiel