Reverse Key Indexes

You can create an index as a reverse key index for performance reasons; they're especially suited for Oracle RAC environments. A reverse key index stores the index entries with their bytes reversed. The ROWIDs are stored in the same format as a regular index. When you insert rows in a column where the database populates one of the columns using an increasing sequence, each new entry will be inserted into the same index block. When each new key value in an index is greater than the previous value, it is said to be a monotonically increasing value. In a RAC database, when multiple sessions simultaneously insert data into monotonically increasing index nodes, it leads to contention for the same index block. A reverse key index ...

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