In the last episode (Sep 23), Peter Brodersen said:
> I have a MyISAM-table with a couple of fields, and about half a million
> rows (datafile is 15MB, indexfile is 10MB) . The server is running under
> MySQL 4.0.21.
> Creating an index on a field takes about two minutes. That's fully
> expected, as the server has to perform an initial sorting for all
> 500000 rows.
> When I try to remove the index, it takes about one minute. I'm just not
> What is the reason for an index drop to take that amount of time?
All ALTER TABLE operations in mysql are done by rebuilding the table in
question and all indexes. You can watch it happen by taking a listing
of the database directory and looking at the #sql tempfiles.