梦想有多远

 

BBED> show

        FILE#           4

        BLOCK#          29

        OFFSET          0

        DBA             0×0100001d (16777245 4,29)

        FILENAME        /u02/boson/users01.dbf

        BIFILE          bifile.bbd

        LISTFILE        /home/oracle/file_nls.log

        BLOCKSIZE       8192

        MODE            Edit

        EDIT            Unrecoverable

        IBASE           Dec

        OBASE           Dec

        WIDTH           80

        COUNT           512

        LOGFILE         log.bbd

        SPOOL           No

 

 

 

BBED> p kcbh;(块头，总共20字节）

struct kcbh, 20 bytes                       @0      

   ub1 type_kcbh                            @0        0×06 trans data

   ub1 frmt_kcbh                            @1        0xa2 (8K的块，REDO是0×22)

   ub1 spare1_kcbh                          @2        0×00

   ub1 spare2_kcbh                          @3        0×00   (以上两个已经不在使用）

   ub4 rdba_kcbh                            @4        0×0100001d (0×0100001d (4/29),文件4块29）

   ub4 bas_kcbh                             @8        0×000457fe （BASE OF SCN)

   ub2 wrp_kcbh                             @12       0×0000      (WRAP OF SCN)

   ub1 seq_kcbh                             @14       0×01        （sequence # of changes at same scn */

   ub1 flg_kcbh                             @15       0×04 (KCBHFCKV)

   ub2 chkval_kcbh                          @16       0×0d7d

   ub2 spare3_kcbh                          @18       0×0000

flg_kcbh:

define KCBHFNEW 0×01 /* new block - zeroed data area */

#define KCBHFDLC 0×02 /* Delayed Logging Change advance SCN/seq */

#define KCBHFCKV 0×04 /* ChecK Value saved-block xor’s to zero */

#define KCBHFTMP 0×08 /* Temporary block */

这是一个可以组合的值 也就是说有为 6 的时候是 2,4 两种情况的组合

 

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