olemus
andmebaasi indeksi halduskoopia,
ainult muutmiseks ja hoolduseks,
lihtkasutajale on kättesaamatu

näiteid
https://www.oracle.com/technetwork/database/enterprise-edition/ot11g-new-features-132182.pdf :
In Oracle Database 11g you can create a “shadow” text index. This can be built while the original index is still in use, and when the index build is complete, the original index can be exchanged for the newly built shadow index. As soon as this is done, queries will automatically transition to the new index.

vt ka
https://en.wikipedia.org/wiki/Shadow_table