Design A Variant Of The Hybrid Merge-join Algorithm For The Case Wher

1.	Design A Variant Of The Hybrid Merge-join Algorithm For The Case Where Both Relations Are Not Physically Sorted, But Both Have A Sorted Secondary Index On The Join Attributes?
Answer» We merge the LEAF entries of the first sorted secondary index with the leaf entries of the second sorted secondary index. The result FILE contains pairs of addresses, the first address in each pair POINTING to a tuple in the first relation, and the second address pointing to a tuple in the second relation. This result file is first sorted on the first relation’s addresses. The relation is then scanned in physical storage order, and addresses in the result file are replaced by the actual tuple values. Then the result file is sorted on the second relation’s addresses, allowing a SCAN of the second relation in physical storage order to complete the JOIN. We merge the leaf entries of the first sorted secondary index with the leaf entries of the second sorted secondary index. The result file contains pairs of addresses, the first address in each pair pointing to a tuple in the first relation, and the second address pointing to a tuple in the second relation. This result file is first sorted on the first relation’s addresses. The relation is then scanned in physical storage order, and addresses in the result file are replaced by the actual tuple values. Then the result file is sorted on the second relation’s addresses, allowing a scan of the second relation in physical storage order to complete the join.

Design A Variant Of The Hybrid Merge-join Algorithm For The Case Where Both Relations Are Not Physically Sorted, But Both Have A Sorted Secondary Index On The Join Attributes?

Answer»

We merge the LEAF entries of the first sorted secondary index with the leaf entries of the second sorted secondary index. The result FILE contains pairs of addresses, the first address in each pair POINTING to a tuple in the first relation, and the second address pointing to a tuple in the second relation. This result file is first sorted on the first relation’s addresses. The relation is then scanned in physical storage order, and addresses in the result file are replaced by the actual tuple values. Then the result file is sorted on the second relation’s addresses, allowing a SCAN of the second relation in physical storage order to complete the JOIN.

We merge the leaf entries of the first sorted secondary index with the leaf entries of the second sorted secondary index. The result file contains pairs of addresses, the first address in each pair pointing to a tuple in the first relation, and the second address pointing to a tuple in the second relation. This result file is first sorted on the first relation’s addresses. The relation is then scanned in physical storage order, and addresses in the result file are replaced by the actual tuple values. Then the result file is sorted on the second relation’s addresses, allowing a scan of the second relation in physical storage order to complete the join.

Design A Variant Of The Hybrid Merge-join Algorithm For The Case Where Both Relations Are Not Physically Sorted, But Both Have A Sorted Secondary Index On The Join Attributes?

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