event 10231 skip corrupted blocks on _table_scans_

请在出现大规模坏块或者用_allow_resetlogs_corruption打开库后(如果够幸运)使用 ，做全库导出   EVENT: 10231 "skip corrupted blocks on _table_scans_" [ID 21205.1]
		Modified 20-APR-2006     Type REFERENCE     Status PUBLISHED

Event: 10231
Text:  skip corrupted blocks on _table_scans_
-------------------------------------------------------------------------------
Cause:
Action: Corrupt blocks are skipped in table scans, and listed in trace files.
 
Explanation:
        This is NOT an error but is a special EVENT code.
        It should *NOT* be used unless explicitly requested by ST support.

   8.1 onwards:
   ~~~~~~~~~~~~
        The "7.2 onwards" notes below still apply but in Oracle8i 
        there is a PL/SQL  which can be used 
        to check corrupt blocks.  See .

        It is possible to simulate 10231 on a table using
        DBMS_REPAIR.SKIP_CORRUPT_BLOCKS('schema','table').
        The SKIP_CORRUPT column of DBA_TABLES shows tables which
        have been marked to allow skipping of corrupt blocks.
 
   7.2 onwards:
   ~~~~~~~~~~~~
	Event 10231 causes SOFTWARE CORRUPT or MEDIA corrupt blocks
	to be skipped on FULL TABLE SCANS only.  (E.g: on export)
	Software corrupt blocks are defined below.  Media corrupt 
        blocks are Oracle blocks where the header field information 
        is not what was expected.  These can now be skipped with
	the 10231 event.

   Before 7.2:
   ~~~~~~~~~~~
        Event 10231 causes SOFTWARE CORRUPT blocks to be skipped on 
        FULL TABLE SCANS only.  (E.g: on export). 

        A 'software corrupt' block is a block that has a SEQ number of ZERO.
        This raises an ORA-1578 error.

	NB: Blocks may be internally corrupt and still cause problems or 
	    raise ORA-1578.  If a block is physically corrupt and the SEQ
	    is not set to ZERO, you cannot use 10231 to skip it.  You have 
	    to try to scan around the block instead.
	
	    To manually corrupt a block and cause it to be skipped you
	    must: Set SEQ to ZERO.
		  Set the INCSEQ at the end of the block to match.


	You can set event numbers 10210, 10211, and 10212 to check blocks 
        at the data level and mark them software corrupt if they are found 
        to be corrupt.  You CANNOT use these events to mark a physically 
        corrupt block as software corrupt because the block never reaches 
        the data layer.

        When a block is skipped, any data in the block is totally ignored.


Usage:  Event="10231 trace name context forever, level 10".
	This should be removed from the instance parameters immediately after
	it has been used.

        Alternatively it can be set at session level:
        alter session set events '10231 trace name context forever, level 10'