dump controlf、file_hdrs 中control seq代表什么?

武汉-SSH

dump controlf、file_hdrs 中control seq代表什么

Control Seq

Maclean Liu(刘相兵

Whenever a controlfile transaction is committed, the controlfile sequence number is incremented. This number is recorded with the block version bitmap and database information entry in the first record section of the controlfile. It is used in the cache header of each controlfile block in place of an SCN to detect possible split blocks from hot backups. It is also used in queries that perform multiple controlfile reads to ensure that a consistent snapshot of the controlfile has been seen. If not, an ORA-00235 error is returned.

SQL> oradebug setmypid;
Statement processed.
SQL> oradebug dump controlf 3;
Statement processed.

DUMP OF CONTROL FILES, Seq # 36056 = 0x8cd8
V10 STYLE FILE HEADER:
        Compatibility Vsn = 169869568=0xa200100
        Db ID=2807279631=0xa753b00f, Db Name='G10R21'
        Activation ID=0=0x0
        Control Seq=36056=0x8cd8, File size=662=0x296
        File Number=0, Blksiz=16384, File Type=1 CONTROL


CONTROL FILES, Seq # 36056 = 0x8cd8


SQL> alter system checkpoint;

System altered.

SQL> oradebug setmypid;
Statement processed.

SQL> oradebug dump  controlf 3;
Statement processed.


DUMP OF CONTROL FILES, Seq # 36059 = 0x8cdb
V10 STYLE FILE HEADER:
        Compatibility Vsn = 169869568=0xa200100
        Db ID=2807279631=0xa753b00f, Db Name='G10R21'
        Activation ID=0=0x0
        Control Seq=36059=0x8cdb, File size=662=0x296
        File Number=0, Blksiz=16384, File Type=1 CONTROL


CONTROL FILES, Seq # 36059 = 0x8cdb



36056 => checkpoint, controlfile transaction commited => 36059 control seq