The table resource_index can be quite huge. The 5 migrations altering its structure in v6.0 can be very long to run and may fail (for example Oracle rollback segment too small). Moreover they may not be reentrant (see SONAR-9989).
Fortunately this table is dropped in version 6.3. The migrations 1201, 1202, 1203, 1204 and 1206 become useless and can be dropped.
On our environment that tests migration from 5.6 to 6.7 on a db with ~200M issues, these 5 migrations are 7 hours long on a total of 23 hours !