Is there any way to see the progress of an ALTER TABLE statement in MySQL?

Question

For example, I issued an ALTER TABLE statement to create an index on a MEDIUMTEXT field in an InnoDB table that has 134k rows where the size of the index was 255 bytes and the average size of the data in the field is 30k. This command has been running for the last 15 minutes or so (and is the only thing running on the database). Is there any way for me to determine if it is going to finish in closer to 5 minutes, 5 hours, or 5 days?

Answer 1

I was able to perform these 2 queries and figure out how many rows remain to be moved.

select count(*) from `myoriginalrable`; select count(*) from `#sql-1e8_11ae5`; 

this was WAY more helpful than comparing the file size on disk, because changing from myisam to innodb etc changes the row size.

Answer 2

In the case of InnoDB tables, one can use SHOW ENGINE INNODB STATUS to find the transaction doing the ALTER TABLE and check how many row locks the TX holds. This is the number of processed rows. Explained in detail here:

http://gabrielcain.com/blog/2009/08/05/mysql-alter-table-and-how-to-observe-progress/

Also MariaDB 5.3 and later has the feature to report progress for some operations (including ALTER TABLE). See:

http://kb.askmonty.org/en/progress-reporting/