MySQL 8.0 Release Notes
MySQL 8.0 Source Code Documentation
The CSV storage engine supports the
CHECK TABLE and
REPAIR TABLE statements to verify
and, if possible, repair a damaged CSV table.
When running the CHECK TABLE
statement, the CSV file will be checked for
validity by looking for the correct field separators, escaped
fields (matching or missing quotation marks), the correct number
of fields compared to the table definition and the existence of a
corresponding CSV metafile. The first invalid
row discovered will report an error. Checking a valid table
produces output like that shown below:
mysql> CHECK TABLE csvtest;
+--------------+-------+----------+----------+
| Table | Op | Msg_type | Msg_text |
+--------------+-------+----------+----------+
| test.csvtest | check | status | OK |
+--------------+-------+----------+----------+A check on a corrupted table returns a fault:
mysql> CHECK TABLE csvtest;
+--------------+-------+----------+----------+
| Table | Op | Msg_type | Msg_text |
+--------------+-------+----------+----------+
| test.csvtest | check | error | Corrupt |
+--------------+-------+----------+----------+
If the check fails, the table is marked as crashed (corrupt). Once
a table has been marked as corrupt, it is automatically repaired
when you next run CHECK TABLE or
execute a SELECT statement. The
corresponding corrupt status and new status will be displayed when
running CHECK TABLE:
mysql> CHECK TABLE csvtest;
+--------------+-------+----------+----------------------------+
| Table | Op | Msg_type | Msg_text |
+--------------+-------+----------+----------------------------+
| test.csvtest | check | warning | Table is marked as crashed |
| test.csvtest | check | status | OK |
+--------------+-------+----------+----------------------------+
To repair a table, use REPAIR
TABLE, which copies as many valid rows from the existing
CSV data as possible, and then replaces the
existing CSV file with the recovered rows. Any
rows beyond the corrupted data are lost.
mysql> REPAIR TABLE csvtest;
+--------------+--------+----------+----------+
| Table | Op | Msg_type | Msg_text |
+--------------+--------+----------+----------+
| test.csvtest | repair | status | OK |
+--------------+--------+----------+----------+
Warning
During repair, only the rows from the CSV
file up to the first damaged row are copied to the new table.
All other rows from the first damaged row to the end of the
table are removed, even valid rows.