dear all,

i would like to ask a question form experts; if i delete records will i get used space or not.




[root@DBS mus]# du -s test_t.*
12K test_t.frm
21G test_t.MYD
4K test_t.MYI

mysql> delete from test_t where time < 1217530799;
Query OK, 43100099 rows affected (7 min 22.06 sec)

mysql> commit;
Query OK, 0 rows affected (0.00 sec)


[root@DBS mus]# du -s test_t.*
12K test_t.frm
21G test_t.MYD
4K test_t.MYI


Any idea ?

MySQL dont like to delete records,

OPTIMIZE TABLE should be used if you have deleted a large part of a table or if you have made many changes to a table with variable-length rows

The records are deleted, but there is free space left in the database file. Even though intuition might suggest otherwise, shrinking the database file is actually a non-trivial operation and MySQL will never try do to that "on-the-fly".