YuMa의 DB 이야기

select * from dba_indexes

where degree != 1; -- parallel 로 되어 있는 것만 출력할 경우

select * from
(select sid, serial#, opname, to_char(start_time,'yyyymmdd hh24:mi:ss') st,
  TRUNC((sofar/totalwork) * 100) as percent_complete,START_TIME,TIME_REMAINING
from v$session_longops
order by start_time desc)
where rownum<=10
;

Character string values storage:
1. CHAR:
§ Stores strings of fixed length.
§ The length parameter s specifies the length of the strings.
§ If the string has smaller length it padded with space at the end
§ It will waste of a lot of disk space.
§ If the string has bigger length it truncated to the scale number of the string.

2. VARCHAR:
§ Stores strings of variable length.
§ The length parameter specifies the maximum length of the strings
§ It stores up to 2000 bytes of characters
§ It will occupy space for NULL values
§ The total length for strings is defined when database was created.

3. VARCHAR(2):
§ Stores strings of variable length.
§ The length parameter specifies the maximum length of the strings
§ It stores up to 4000 bytes of characters
§ It will not occupy space for NULL values
§ The total length of strings is defined when strings are given

Read more: http://wiki.answers.com/Q/What_is_difference_between_varchar_and_varchar2#ixzz1y8EQfB7P