Concepts on updating table Data

Updating the column value to the same value modifies the table block. data in the table block is physically modified. But, the corresponding index entry is not modified.


Updating the column value to a different value modifies both table and index blocks. Updating an indexed column value results in a delete and insert of index entries in the index leaf block.

Delete of an index entry does not delete the entry physically, rather marks the entry with a flag. Future inserts into this block will reuse the space allocated.