Repair data block corruption in Oracle

1. Create a tablespace for the experiment.

Create tablespace block datafile size 1 M extent management local;-because it is 11 GB, AMS is used.

Alter user ff default tablespace block;

Alter user ff quota unlimited on block;

2. corrupt data files

Close the database, use the editor to modify a few characters, and then start the database.

An error occurs when access to the damaged block.

3. Use dbv to check the data file.

Dbv file = block. dbf blocksize = 8192

Assume that 35th blocks are damaged.

4. Recovery steps

① Select tablespace_name, segment_type, owner, segment_name from dba_extents where file_id = 4 and 35 between block_id and block_id + blocks-1;

If data is lost, OK

Set internal events and skip damaged data blocks during full table scan.

Alter system set events = '10231 trace name context forever, level 10 ′;

Then, you can use exp and imp for import and export and recovery. However, this leads to data loss in dependent blocks.

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