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George Wilkinson
2024-01-21 00:34:10 +00:00
parent 7a6e5c1b31
commit 65ac667d88
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Semester 2/Database Systems/Week 1/Week 1 Database Systems.md
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@@ -34,4 +34,4 @@ Purpose is to transform a query written in a high level language into correct an
- Move SELECT operations down the tree - Move SELECT operations down the tree
- Apply more restrictive SELECT operations first ( eg. equalities before range queries ) - Apply more restrictive SELECT operations first ( eg. equalities before range queries )
- Replace Cartesian products followed by selection with theta joins ( eg. *sigma(f) ( RxS )* -> *R theta(f) S* ) - Replace Cartesian products followed by selection with theta joins ( eg. *sigma(f) ( RxS )* -> *R theta(f) S* )
- Move PROJECT operations down the query tree ( add project operations as inputs to theta joins ) - Move PROJECT operations down the query tree ( add project operations as inputs to theta joins ).