Question

How many logical query processing phases does each type of join have and what are they?

Answer 1

Inner joins have two logical query processing phases: join operation and filter operation. Outer joins have three logical query processing phases: join operation, filter operation, and null value handling.

Step-by-step explanation:

In database query processing, there are different phases involved in processing join operations, depending on the type of join being executed. The two most common types of joins are the inner join and the outer join.

For the inner join, there are two logical query processing phases:

1. Join operation: This phase combines the rows from two tables based on the specified join condition.
2. Filter operation: This phase applies any additional filter conditions to the result of the join.

For the outer join, there are three logical query processing phases:

1. Join operation: This phase combines the rows from two tables based on the specified join condition, similar to the inner join.
2. Filter operation: This phase applies any additional filter conditions to the result of the join, similar to the inner join.
3. Null value handling: This phase handles the cases where there is no match between rows of the joined tables, by including or excluding these unmatched rows in the result.