Skipping corrupt blocks - Amazon Relational Database Service
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Skipping corrupt blocks

To skip corrupt blocks during index and table scans, use the rdsadmin.rdsadmin_dbms_repair package.

The following procedures wrap the functionality of the sys.dbms_repair.admin_table procedure and take no parameters:

  • rdsadmin.rdsadmin_dbms_repair.create_repair_table

  • rdsadmin.rdsadmin_dbms_repair.create_orphan_keys_table

  • rdsadmin.rdsadmin_dbms_repair.drop_repair_table

  • rdsadmin.rdsadmin_dbms_repair.drop_orphan_keys_table

  • rdsadmin.rdsadmin_dbms_repair.purge_repair_table

  • rdsadmin.rdsadmin_dbms_repair.purge_orphan_keys_table

The following procedures take the same parameters as their counterparts in the DBMS_REPAIR package for Oracle databases:

  • rdsadmin.rdsadmin_dbms_repair.check_object

  • rdsadmin.rdsadmin_dbms_repair.dump_orphan_keys

  • rdsadmin.rdsadmin_dbms_repair.fix_corrupt_blocks

  • rdsadmin.rdsadmin_dbms_repair.rebuild_freelists

  • rdsadmin.rdsadmin_dbms_repair.segment_fix_status

  • rdsadmin.rdsadmin_dbms_repair.skip_corrupt_blocks

For more information about handling database corruption, see DBMS_REPAIR in the Oracle documentation.

Example Responding to corrupt blocks

This example shows the basic workflow for responding to corrupt blocks. Your steps will depend on the location and nature of your block corruption.

Important

Before attempting to repair corrupt blocks, review the DBMS_REPAIR documentation carefully.

To skip corrupt blocks during index and table scans

  1. Run the following procedures to create repair tables if they don't already exist.

    EXEC rdsadmin.rdsadmin_dbms_repair.create_repair_table;
EXEC rdsadmin.rdsadmin_dbms_repair.create_orphan_keys_table;

  2. Run the following procedures to check for existing records and purge them if appropriate.

    SELECT COUNT(*) FROM SYS.REPAIR_TABLE;
SELECT COUNT(*) FROM SYS.ORPHAN_KEY_TABLE;
SELECT COUNT(*) FROM SYS.DBA_REPAIR_TABLE;
SELECT COUNT(*) FROM SYS.DBA_ORPHAN_KEY_TABLE;

EXEC rdsadmin.rdsadmin_dbms_repair.purge_repair_table;
EXEC rdsadmin.rdsadmin_dbms_repair.purge_orphan_keys_table;

  3. Run the following procedure to check for corrupt blocks.

    SET SERVEROUTPUT ON
DECLARE v_num_corrupt INT;
BEGIN
  v_num_corrupt := 0;
  rdsadmin.rdsadmin_dbms_repair.check_object (
    schema_name => '&corruptionOwner',
    object_name => '&corruptionTable',
    corrupt_count =>  v_num_corrupt
  );
  dbms_output.put_line('number corrupt: '||to_char(v_num_corrupt));
END;
/

COL CORRUPT_DESCRIPTION FORMAT a30
COL REPAIR_DESCRIPTION FORMAT a30

SELECT OBJECT_NAME, BLOCK_ID, CORRUPT_TYPE, MARKED_CORRUPT, 
       CORRUPT_DESCRIPTION, REPAIR_DESCRIPTION 
FROM   SYS.REPAIR_TABLE;

SELECT SKIP_CORRUPT 
FROM   DBA_TABLES 
WHERE  OWNER = '&corruptionOwner'
AND    TABLE_NAME = '&corruptionTable';

  4. Use the skip_corrupt_blocks procedure to enable or disable corruption skipping for affected tables. Depending on the situation, you may also need to extract data to a new table, and then drop the table containing the corrupt block.

    Run the following procedure to enable corruption skipping for affected tables.

    begin
  rdsadmin.rdsadmin_dbms_repair.skip_corrupt_blocks (
    schema_name => '&corruptionOwner',
    object_name => '&corruptionTable',
    object_type => rdsadmin.rdsadmin_dbms_repair.table_object,
    flags => rdsadmin.rdsadmin_dbms_repair.skip_flag);
end;
/
select skip_corrupt from dba_tables where owner = '&corruptionOwner' and table_name = '&corruptionTable';

    Run the following procedure to disable corruption skipping.

    begin
  rdsadmin.rdsadmin_dbms_repair.skip_corrupt_blocks (
    schema_name => '&corruptionOwner',
    object_name => '&corruptionTable',
    object_type => rdsadmin.rdsadmin_dbms_repair.table_object,
    flags => rdsadmin.rdsadmin_dbms_repair.noskip_flag);
end;
/

select skip_corrupt from dba_tables where owner = '&corruptionOwner' and table_name = '&corruptionTable';

  5. When you have completed all repair work, run the following procedures to drop the repair tables.

    EXEC rdsadmin.rdsadmin_dbms_repair.drop_repair_table;
EXEC rdsadmin.rdsadmin_dbms_repair.drop_orphan_keys_table;