Phpbb3.1 MyIsam database corrupted

Question

everyone! I'm trying to avoid breaking of my database in the phpbb3.1 forum. It was crushed twice this month. So I have two questions:
1) Is it safe to convert MyISAM to InnoDB? I mean will extensions work fine? Will forum be workable after updating to next version?
2) In which way I can avoid base corrupting?

p.s. I also posted this question here: https://www.phpbb.com/community/viewtopic.php?f=466&t=2436326

Answer 1

I'll venture a guess. You had a power failure, and when it came back up, MySQL was complaining that some index on some table was corrupted? And that table was MyISAM?

1. Use myisamchk to repair the tables.
2. Review the gotchas in http://mysql.rjweb.org/doc.php/myisam2innodb to see if conversion to InnoDB will add new woes. There probably won't be any. A 2-part PRIMARY KEY is about the only thing that is not implemented in InnoDB. Also, if you have too old a version of MySQL, InnoDB may not yet have FULLTEXT indexes (if you need them).
3. Change my.cnf: key_buffer_size = 20M and innodb_buffer_pool_size equal to about half of available memory.
4. ALTER TABLE xx ENGINE=InnoDB; for each table xx.

I think (but am not sure) that each update/delete/insert marks the table as possibly corrupt. It writes the changes, but does not clear the mark. When mysqld shuts down cleanly, everything is flushed to disk and these flags are cleared. When mysqld comes back up, it complains about the flags that did not get cleared. So...

Whether or not an index is marked as corrupt depends solely on whether you modified that index and crashed. (Every table has some index, yes?)

Normally, MySQL manages to flush changes to disk before a crash. Only occasionally does the crash happen at a time where the index will really be corrupt. There is a "quick" mode on the repair that simply clears the flag -- you could try that. But if you ever get a mysterious "can't find record" when you know the records exists, you'd better REPAIR it.