Gate2020 cs Q60

60Consider a database implemented using B+ tree for file indexing and installed a disk drive with block size of 4 KB. The size of the search key is 12 bytes and size of tree/disk pointer is 8 bytes. Assume that the database has one million records. Also assume that no node of the B+ tree and no records are present initially in main memory. Consider that each record fits into one disk block. The minimum number of disk accesses required to retrieve any record in the database is ______.

Note – Numerical Type question

Option : A
Explanation :
No. of records = 10⁶
Block size = 8 KB
Search key = 13 bytes
Block pointer size = 8 bytes
Balancing factor of index file = [Block size /(search key + Block pointer)]
= [4KB/(12+8)] = [2¹²/20]
Balancing Factor of index file =204

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