Ace Test Series: Databases - B Tree

Question

When would you want to use a B-tree instead of B+ Tree?

1. When sequential access to key values is never required.

2. When sequential access to key values is required.

3. When both Direct and sequential access is required.

4. When Direct access is required without sequential access.

Answer 1

Option no 4 is correct

The major draw back of B-Tree is the difficulty of Traversing the keys sequentially. The B+ Tree retains the rapid random access property of the B-Tree while also allowing rapid sequential access.  So When Direct Access is needed without sequential access B-Tree is preferred.

The primary distinction between B-tree and B+tree is that B-tree eliminates the redundant storage of search key values.Since search keys are not repeated in the B-tree,we may not be able to store the index using fewer tree nodes than in corresponding B+tree index.However,since search key that appear in non-leaf nodes appear nowhere else in B-tree,we are forced to include an additional pointer field for each search key in a non-leaf node. Their are space advantages for B-tree, as repetition does not occur and can be used for large indices.

ref: Data Structures Using C// Author: Aaro M Tenenbaum

@Arjun Sir, please correct if I am wrong

Thanks in Advance

Answer 2

answer is 2, because in B Trees we have to sequentially search the keys. In B+ tree data is ordered in sequential linked list and the data is stored in leaf nodes but in B tree the leaf nodes cannot  be stored in linked list due to lack of the sibling pointers, hence use B Trees when only sequential access is required.

Comments

option (4) is correct.

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I am also thinking that option 4 is correct.

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In B+ tree , all keys and its pointer ar stored at leaf as a linked list.

lets <k1,k2> <k3,k4> <k5,k6> are leaf nodes of a B+ tree.
If we want data from k2 to k5 , in that case B+ tree is preferable.
but in B tree keys might be at different level so sequential search might not be effective.

if we want to search key K4.
in B+ tree we have to come to leaf to get the data pointer, in B tree we might get k4 at intermediate node.
So here B tree is preferred.
I think Option 4 is correct.