[20171206]rman与truncate2.txt

[20171206]rman与truncate2.txt

--//上午测试发现truncate的表在做rman备份时还要做8个extents的备份.
--//不知道自己的猜测是否正确,选择一个使用UNIFORM SIZE 的表空间测试看看.

1.环境:
SCOTT@book> @ &r/ver1
PORT_STRING                    VERSION        BANNER
------------------------------ -------------- --------------------------------------------------------------------------------
x86_64/Linux 2.4.xx            11.2.0.4.0     Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production

CREATE TABLESPACE T01 DATAFILE
  '/mnt/ramdisk/book/T01.dbf' SIZE 20M AUTOEXTEND OFF
LOGGING
EXTENT MANAGEMENT LOCAL UNIFORM SIZE 40K
BLOCKSIZE 8K
SEGMENT SPACE MANAGEMENT MANUAL
FLASHBACK ON;

create table t01 tablespace t01 as select rownum id ,to_char(rownum,'FM000000')||lpad('A',26,'A') name from dual connect by level<=2e5;

SCOTT@book> truncate table t01 ;
Table truncated.

SCOTT@book> alter system checkpoint ;
System altered.

SCOTT@book> alter system checkpoint ;
System altered.

RMAN> backup datafile 7 format '/home/oracle/backup/T1z_%U';
Starting backup at 2017-12-06 15:10:42
using channel ORA_DISK_1
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00007 name=/mnt/ramdisk/book/T01.dbf
channel ORA_DISK_1: starting piece 1 at 2017-12-06 15:10:42
channel ORA_DISK_1: finished piece 1 at 2017-12-06 15:10:43
piece handle=/home/oracle/backup/T1z_hdslesji_1_1 tag=TAG20171206T151042 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
Finished backup at 2017-12-06 15:10:43

$ strings -t d T1z_hdslesji_1_1 | grep 'AAAAA'|head -1
  83254 K 000174AAAAAAAAAAAAAAAAAAAAAAAAAA,
$ strings -t d T1z_hdslesji_1_1 | grep 'AAAAA'|tail -1
 401369 B_ 006539AAAAAAAAAAAAAAAAAAAAAAAAAA/
$ strings -t d T1z_hdslesji_1_1 | grep 'AAAAA'|wc
   6710   18083  295828

SCOTT@book> drop table t01 purge ;
Table dropped.

SCOTT@book> create table t01 tablespace t01 as select rownum id ,to_char(rownum,'FM000000')||lpad('A',26,'A') name from dual connect by level<=2e5;
Table created.

SCOTT@book> column name format a32
SCOTT@book> select rowid,t01.* from t01 where id in (174,6539,6710);
ROWID                      ID NAME
------------------ ---------- --------------------------------
AAAWMCAAHAAAAAJACt        174 000174AAAAAAAAAAAAAAAAAAAAAAAAAA
AAAWMCAAHAAAAAvAAA       6539 006539AAAAAAAAAAAAAAAAAAAAAAAAAA
AAAWMCAAHAAAAAvACr       6710 006710AAAAAAAAAAAAAAAAAAAAAAAAAA

SCOTT@book> @ &r/rowid  AAAWMCAAHAAAAAJACt
    OBJECT       FILE      BLOCK        ROW ROWID_DBA            DBA   TEXT
---------- ---------- ---------- ---------- -------------------- ----- ----------------------------------------
     90882          7          9        173  0x1C00009           7,9   alter system dump datafile 7 block 9 ;

SCOTT@book> @ &r/rowid  AAAWMCAAHAAAAAvAAA
    OBJECT       FILE      BLOCK        ROW ROWID_DBA            DBA   TEXT
---------- ---------- ---------- ---------- -------------------- ----- ----------------------------------------
     90882          7         47          0  0x1C0002F           7,47  alter system dump datafile 7 block 47 ;

SCOTT@book> @ &r/rowid  AAAWMCAAHAAAAAvACr
    OBJECT       FILE      BLOCK        ROW ROWID_DBA            DBA   TEXT
---------- ---------- ---------- ---------- -------------------- ----- ----------------------------------------
     90882          7         47        171  0x1C0002F           7,47  alter system dump datafile 7 block 47 ;

SCOTT@book> select * from (select * from dba_extents where segment_name='T01' order by EXTENT_ID) where rownum<=10;
OWNER  SEGMENT_NAME SEGMENT_TYPE TABLESPACE_NAME EXTENT_ID FILE_ID BLOCK_ID BYTES BLOCKS RELATIVE_FNO
------ ------------ ------------ --------------- --------- ------- -------- ----- ------ ------------
SCOTT  T01          TABLE        T01                     0       7        8 40960      5            7
SCOTT  T01          TABLE        T01                     1       7       13 40960      5            7
SCOTT  T01          TABLE        T01                     2       7       18 40960      5            7
SCOTT  T01          TABLE        T01                     3       7       23 40960      5            7
SCOTT  T01          TABLE        T01                     4       7       28 40960      5            7
SCOTT  T01          TABLE        T01                     5       7       33 40960      5            7
SCOTT  T01          TABLE        T01                     6       7       38 40960      5            7
SCOTT  T01          TABLE        T01                     7       7       43 40960      5            7
SCOTT  T01          TABLE        T01                     8       7       48 40960      5            7
SCOTT  T01          TABLE        T01                     9       7       53 40960      5            7
10 rows selected.

--//确实是8个extents.