Logical Query Processing Phase Details
This section describes the logical query processing phases in detail by applying them to the given sample query.
Step 1: Performing a Cartesian Product (Cross Join)
A Cartesian product (a cross join, or an unrestricted join) is performed between the first two tables that appear in the FROM clause, and as a result, virtual table VT1 is generated. VT1 contains one row for every possible combination of a row from the left table and a row from the right table. If the left table contains n rows and the right table contains m rows, VT1 will contain n × m rows. The columns in VT1 are qualified (prefixed) with their source table names (or table aliases, if you specified ones in the query). In the subsequent steps (step ...
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