Checking and Repairing CSV Tables

CSV tables support the CHECK TABLE and REPAIR TABLE statements.

CHECK TABLE will mark the table as corrupt if it finds a problem, while REPAIR TABLE will restore rows until the first corrupted row, discarding the rest.

Examples

CREATE TABLE csv_test (
  x INT NOT NULL, y DATE NOT NULL, z CHAR(10) NOT NULL
  ) ENGINE=CSV;

INSERT INTO csv_test VALUES
    (1,CURDATE(),'one'),
    (2,CURDATE(),'two'),
    (3,CURDATE(),'three');

SELECT * FROM csv_test;
+---+------------+-------+
| x | y          | z     |
+---+------------+-------+
| 1 | 2013-07-08 | one   |
| 2 | 2013-07-08 | two   |
| 3 | 2013-07-08 | three |
+---+------------+-------+

Using an editor, the actual file will look as follows

$ cat csv_test.CSV
1,"2013-07-08","one"
2,"2013-07-08","two"
3,"2013-07-08","three"

Let's introduce some corruption with an unwanted quote in the 2nd row:

1,"2013-07-08","one"
2","2013-07-08","two"
3,"2013-07-08","three"

CHECK TABLE csv_test;
+---------------+-------+----------+----------+
| Table         | Op    | Msg_type | Msg_text |
+---------------+-------+----------+----------+
| test.csv_test | check | error    | Corrupt  |
+---------------+-------+----------+----------+

We can repair this, but all rows from the corrupt row onwards will be lost:

REPAIR TABLE csv_test;
+---------------+--------+----------+----------------------------------------+
| Table         | Op     | Msg_type | Msg_text                               |
+---------------+--------+----------+----------------------------------------+
| test.csv_test | repair | Warning  | Data truncated for column 'x' at row 2 |
| test.csv_test | repair | status   | OK                                     |
+---------------+--------+----------+----------------------------------------+

SELECT * FROM csv_test;
+---+------------+-----+
| x | y          | z   |
+---+------------+-----+
| 1 | 2013-07-08 | one |
+---+------------+-----+

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