15.4 The CSV Storage Engine

15.4.1 Repairing and Checking CSV Tables

15.4.2 CSV Limitations

The CSV storage engine stores data in text files using comma-separated values format.

The CSV storage engine is always compiled into the MySQL server.

To examine the source for the CSV engine, look in the storage/csv directory of a MySQL source distribution.

When you create a CSV table, the server creates a table format file in the database directory. The file begins with the table name and has an .frm extension. The storage engine also creates plain text data file having a name that begins with the table name and has a .CSV extension. When you store data into the table, the storage engine saves it into the data file in comma-separated values format.

mysql> CREATE TABLE test (i INT NOT NULL, c CHAR(10) NOT NULL)
       ENGINE = CSV;
Query OK, 0 rows affected (0.06 sec)

mysql> INSERT INTO test VALUES(1,'record one'),(2,'record two');
Query OK, 2 rows affected (0.05 sec)
Records: 2  Duplicates: 0  Warnings: 0

mysql> SELECT * FROM test;
+---+------------+
| i | c          |
+---+------------+
| 1 | record one |
| 2 | record two |
+---+------------+
2 rows in set (0.00 sec)

Creating a CSV table also creates a corresponding metafile that stores the state of the table and the number of rows that exist in the table. The name of this file is the same as the name of the table with the extension CSM.

If you examine the test.CSV file in the database directory created by executing the preceding statements, its contents should look like this:

"1","record one"
"2","record two"

This format can be read, and even written, by spreadsheet applications such as Microsoft Excel.