Pause and Resume index build or maintenance on demand

Pausing index build or maintenance will help in cases

• Where new index build is causing high CPU along with other load
• Where we want to reduce the CPU consumption or Disk usage and still keep the index
• Where we want to do some other CPU intensive task pausing the index build
• During rollbacks to save CPU usage
  etc..

Optionally we can also consider to drop the data on the disk too if needed.

Reference:
==============================================================
Usability

An unusable index, which is ignored by the optimizer, is not maintained by DML operations. An unusable index can improve the performance of bulk loads. Instead of dropping an index and later re-creating it, you can make the index unusable and then rebuild it. Unusable indexes and index partitions do not consume space. When you make a usable index unusable, the database drops its index segment.
===============================================================