Clarifications/corrections to project 3:

11/25/2004
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Function 11:
Function 11 should toggle a debug flag (set to false, by default) that prints out a message whenever a bucket is split or merged.  In the case of a split, you should print out something to the effect of "Insert of key A causes bucket B to split.  Creating bucket C.  Inserting key D into node E for bucket C."  In other words, you should describe what happens when a split occurs (on any bucket), mentioning all the affected buckets and relevant keys.  If you implement merge, the message should have similar information.


11/27/2004
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When a file is created, it should be 128B long.  One for the header block, and one for the empty leaf bucket.


11/28/2004
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Implementing non-unique key handling:
When you allow non-unique keys, your leaf pointers must point to buckets containing the values that correspond to each key.  That is, if you insert the following pairs:

1,1
1,2
1,3
1,4

Then, you have inserted four values for the single key 1.  Your B+-tree should contain a single leaf node with the single key 1.  The pointer corresponding to this key should point to a bucket containing the values 1, 2, 3, and 4.

Now, assume you insert 2,5 into the index.  Then your B+-tree should grow by one bucket, which contains the values corresponding to the key 2.  The leaf should contain a pointer to this bucket.

Now, your B+-tree file contains leaves and value buckets.  This is a very interesting type of tree, and you have to modify many index functions to work with it.

Splitting the value buckets:  Consider that you put values into a bucket.  The bucket has a limited capacity.  Assume that the capacity if 5 values.  After five values, you must make an overflow bucket to store the rest of the values.

Searching the buckets:  When you do a lookup for a key, you must return all the key's associated values.


Implementing the file manager:
I will no longer offer the file manager as an extra credit option.  If you do the non-unique key handling, then you will get credit for the file manager extra credit option.