Examine and compare the query plans for queries a-c above - in one brief sentenc

Question

Examine and compare the query plans for queries a-c above - in one brief sentence, what can you observe about B+ tree indexes and their usefulness for equality and different LIKE queries? (Enter your observation below.)

Before created index

After index been created

a) SELECT FROM Bird WHERE Bird.first name Elizabeth Query cost: 5.80 query block #1 5.8 24 rows Full Table Scan Bird b) SELECT FROM Bird WHERE Bird first name LIKE %abeth Query cost: 5.80 query block #1 5.8 24 rows Full Table Scan Bird c) SELECT FROM Bird WHERE Bird first name LIKE Eliz%'; Query cost: 5.800 query block #1 5.8 24 rows Full Table Scan Bird

Explanation / Answer

In the first statement, only rows with Bird.first_name <= 'Elizabeth' are only considered.

In the second statement, only rows with 'abeth' <= Bird.first_name < 'abeti' are considered.

In the second statement, only rows with 'Eliz' <= Bird.first_name < 'Eliza' are considered.

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