chap indexing as mentioned earliera buffer pool should be used to manage nodes of the -tree several nodes of the tree would typically be in main memory at one time the most straightforward approach is to use standard method such as lru to do node replacement howeversometimes it might be desirable to "lockcertain nodes such as the root into the buffer pool in generalif the buffer pool is even of modest size (say at least twice the depth of the tree)no special techniques for node replacement will be required because the upper-level nodes will naturally be accessed frequently further reading for an expanded discussion of the issues touched on in this see general file processing text such as file structuresa conceptual toolkit by folk and zoellick [fz in particularfolk and zoellick provide good discussion of the relationship between primary and secondary indices the most thorough discussion on various implementations for the -tree is the survey article by comer [com also see [sal for further details on implementing -trees see shaffer and brown [sb for discussion of buffer pool management strategies for -tree-like data structures exercises assume that computer system has disk blocks of bytesand that you are storing records that have -byte keys and -byte data fields the records are sorted and packed sequentially into the disk file (aassume that linear index uses bytes to store the key and bytes to store the block id for the associated records what is the greatest number of records that can be stored in the file if linear index of size kb is used(bwhat is the greatest number of records that can be stored in the file if the linear index is also stored on disk (and thus its size is limited only by the second-level indexwhen using second-level index of bytes ( key valuesas illustrated by figure each element of the second-level index references the smallest key value for disk block of the linear index assume that computer system has disk blocks of bytesand that you are storing records that have -byte keys and -byte data fields the records are sorted and packed sequentially into the disk file