CSC 472 Introduction to Database Systems Project Consider the hashing approach for computing aggregations. If the size of the hash table is too large to fit in memory, then the DBMS has to spill it to disk. During the Partition phase, a hash function h1 is used to split tuples into partitions on disk based on target hash key. During the ReHash phase, the DBMS can store pairs of the form (GroupByKey -> RunningValue) to compute the aggregation. Which of the following is FALSE ? Group of answer choices The Partition phase will put all tuples that match (using h1) into the same partition. To insert a new tuple into the hash table, a new (GroupByKey -> RunningValue) pair is inserted if it finds a matching GroupByKey. A second hash function (e.g., h2) is used in the ReHash phase. The RunningValue could be updated during the ReHash phase.

In what ways does clustering impact hashing performance as a whole?

Please answer all parts of the question, thanks

Explain the collision resolution techniques used in hash tables when dealing with key collisions in dictionaries.

Given a sequence of 5 keys < 53, 66, 32, 41, 88 > for searching task: a) Given the hash function H(k) = (3.k) mod 7, insert the keys above according to its original order (from left to right) into a hash table of 7 slots. Indicate the cases of collision. Clearly show the steps and calculation with a table. b) In case of any collisions found above in a) part, determine the new slot for each collided case using Linear Probing to solve the collision problem. Clearly show your answer for each identified case. No step of calculation required. o (Answer with “NO collision found”, in case there is no collisions found above) c) In case of any collisions found above in a) part, determine the new slot ONLY for the first collided case using Double-Hashing (with functions below) to solve the collision problem. Clearly show the steps of your calculation. d1 = H(k) = (3.k) mod 7 di = (di−1 + ((5·k) mod 6) + 1) mod 7 , i ≥ 2 o (Answer with “NO collision found”, in case there is no collisions…

For every block chain, what information is always registered within every block? (a)The previous block is hash, (b)The current block is hash, (c)The next block is hash, (d) all the previous block is hash?

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Open hashing and closed hashing are two different types of hashing (overflowchaining)Hashing using a closed loop

Problem 5 ( ,. Suppose that your hash function resolves collisions using open addressing with double hashing, which we discussed in the class. The double hashing method uses two hash functions h and h'. Assume that the table size N = 13, h(k) = k mod 13, h '(k) = 1 + (k mod 11), and the current content of the hash table is: 0 1 2 3 4 5 6 7 8 9 10 11 12 28 98 59 22 43 51 If you insert k = 15 to this hash table, where will it be placed in the hash table? You must describe, step by step, how the location of the key is determined.

What is the overall effect of clustering on hashing performance?