I loaded about 15 million records into a MySQL table, and
then did an ALTER TABLE to add an index on a BIGINT field.
The ALTER TABLE has been running for about 30 hours now.
About how long should that take? It took less than
24 hours to create the table with INSERT statements.

Does an ALTER TABLE force a rebuild of all the table
indices, or are the existing ones copied?

Thanks.

John Nagle