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2. What problems we would have during:  Insertion  Deletion  Update 2

3.  What would we do for record insertion?  Find a block with enough empty space  Get a new block  But what would happen if we should insert the record in a specific block? 3 Offset Table Unused Record 4 Record 3 Record 2 Record 1

4.  There are two possibilities: 1. There is enough room in the target block 2. There is not enough room in the target block  In the 1 st case, insert and update the offset table  In the 2 nd case, there are two approaches:  Find space on a nearby block and slide the records  Create an overflow block 4

5.  What is an overflow block?  It is another block in which we put the records that theoretically belong to this block.  In block’s header, there is a pointer to an overflow. 5

6.  The usual technique is to put a tombstone in place of the record.  This is not the case that we delete the record physically.  This is a permanent tombstone until the database is reconstructed. 6

7.  Where to put the sign of deletion?  If using offset table in the block header, put null in the pointer’s place  If using a map table, put null in physical address 7

8.  No problem if fixed length records  The problems arise for variable length records  We have all problems mentioned for insertion and deletion 8

9.  If the new record is shorter:  Slide down the records to consolidate the free spaces  If the new record is longer:  Slide down the records to make room  Create an overflow block 9

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