Oracle
1Z0-883 · Question #45
Consider the following: Mysql> EXPLAIN SELECT FROM City WHERE Name = Jacksonville' AND CountryCode = USA' \G **************************** 1. row ***************************** Id: 1 Select_type…
The correct answer is D. It shows how many bytes will be used from each index row. See the full explanation below for the reasoning.
Question
Consider the following:
Mysql> EXPLAIN SELECT * FROM City WHERE Name = Jacksonville' AND CountryCode = USA' \G ******************************** 1. row ******************************** Id: 1 Select_type: SIMPLE Table: City Type: ref Possible_keys: name_country_index Key: name_country_index Ref: const, const Rows: 1 Extra: Using where Which statement best describes the meaning of the value for the key_len column?
Options
- AIt shows the total size of the index row.
- BIt shows how many columns in the index are examined.
- CIt shows the number of characters indexed in the key.
- DIt shows how many bytes will be used from each index row.
How the community answered
(29 responses)- A7% (2)
- B3% (1)
- C17% (5)
- D72% (21)
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