[abfan1127]

Could you create a temporary high memory slave MySQL server, sync the master, add the index, sync back to master, and decommission the temporary high memory? I don't know enough about master/slave operations to know if it would work.

[wolf550e]

'malinens doesn't have the storage space to store an index over a column if all values in the column are indexed. They want to index only some values, but not others. This feature does not exist in MySQL.