Behaviour of INDEX in RDBMS

Q1 => Does an INDEX get purged and created on each insert, update, delete?

Q2 => If yes, how to use an index in a table where there wi开发者_如何学Goll be 60% read, 30% insert, 10% delete?

---

The indexes are "maintained" for each insert/update/delete. That means the affected records of the affected indexes will be inserted/deleted.

http://use-the-index-luke.com/

---

1. No! An index is updated on each operation, but it is not rebuilt on each operation (that would have a completely prohibitive cost).

2. Moot since the answer to Q1 is No.