Description:
Via: https://github.com/Tokutek/tokudb-engine/wiki/Dynamic-plugins
Dynamic plugins do not work in MySQL. For example, when a table is dropped, MySQL will not inform the storage engine if the dynamic plugin number assigned to a storage engine changes. Here is how to reproduce the problem.
How to repeat:
Step 1. Hack the example storage engine to create a file for each table and to unlink the file when the table is deleted.
$ diff ha_example.cc ~/Downloads/mysql-5.6.21/storage/example
836,839d835
< int r = ::unlink(name);
< if (r == -1)
< r = errno;
< assert(r == 0);
913,915d908
< int fd = ::creat(name, 0777);
< assert(fd != -1);
< ::close(fd);
Step 2. Startup MySQL and install the example storage engine.
Step 3. Create a table s.
create table test.s (id int) engine=example;
There should be a file s.frm and a file s in the test directory.
Step 4. Drop table s. All of the files in the test directory are removed.
Step 5. Create another table t.
create table test.t (id int) engine=example;
There should be a file t.frm and a file t in the test directory.
Step 6. Shutdown MySQL
Step 7. Change the plugin number in the t.frm file from 42 to 43. 42 is the plugin number that is stored in byte 3 of the frm file. This can happen if the sequence of dynamic plugins that are installed changes.
$ hexdump -C t.frm
00000000 fe 01 09 2a 03 00 00 10 01 00 00 30 00 00 10 00 |...*.......0....|
00000010 05 00 00 00 00 00 00 00 00 00 00 02 08 00 08 00 |................|
00000020 00 05 00 00 00 00 08 00 00 00 00 00 00 00 00 10 |................|
00000030 00 00 00 bd c5 00 00 1b 00 00 00 00 00 00 00 00 |................|
00000040 2f 2f 00 00 20 00 00 00 00 00 00 00 00 00 00 00 |//.. ...........|
00000050 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
00001000 00 00 00 00 02 00 ff 00 00 00 00 00 00 00 00 00 |................|
00001010 ff 00 00 00 00 00 00 07 00 45 58 41 4d 50 4c 45 |.........EXAMPLE|
Step 8. Start MySQL
Step 9. Drop table t.
Problem: MySQL does not call the example storage engine's delete_tablehandler method, so the files managed by the example storage engine are NOT cleaned up.
Suggested fix:
MySQL must call the example storage engine's delete_table handler method.
