"If your table fits in ram, or rather, the maximum number of tables you're repairing in parallel fit in ram, REPAIRs are fairly fast.
If it doesn't, they aren't. This is because to rebuild the secondary indexes it needs to do multiple…"
"I am not convinced that replaying the binary logs would be faster than a repair.
You might not get the same data, for a start. Secondly, you'll end up doing normal inserts rather than a "repair by sorting" index rebuild, normal…"
"Unfortunately there is no way to specify a different temp dir for temporary tables and filesort files. Filesort files can get much larger than temporary tables, and you get very large ones created during MyISAM REPAIR and ALTER operations.