Shulou(Shulou.com)06/01 Report--

Description of the index

The index is an optional structure related to the table, which is logically and physically independent of the data of the table. The index can optimize the query, but not the DML operation. Oracle maintains the index automatically. Frequent DML operations will lead to a lot of index maintenance.

Typically, in order to retrieve table data, the database reads the index block first and then the corresponding table block in an alternate manner.

1 large table, number of rows returned = 4

2 PCT_USED

0.2

Alter index ind_1 rebuild [online] [tablespace name]

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