We have tables with over 10 or 20 millions of records (MyISAM tables if that matters).
Building new index, removing old index is taking at least a quarter of hour.
While doing this operation, MySQL seems to lock the table or at least the load is so big that any operations on the table is delayed after the end of index operation.
I wonder how DBA usually deal with this kind of problem on MySQL ?
I cannot imagine a strategy which would help keeping the service a hundred per cent available while achieving an index reconfiguration.