- Database Question 1 (49.99 KiB) Viewed 48 times
Database Question:
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answerhappygod
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Database Question:
Database Question:
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 hy 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 ? The Partition phase will put all tuples that match (using hî) 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., h) is used in the ReHash phase. The RunningValue could be updated during the ReHash phase.
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 hy 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 ? The Partition phase will put all tuples that match (using hî) 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., h) is used in the ReHash phase. The RunningValue could be updated during the ReHash phase.
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