will save memory.C. It will disable InnoDBs associated memory buffers and data structures, which will savememory.Answer:CQUESTION:125It is important to analyze queries that involve joins with EXPLAIN because...A. Joins are more prone to mistakes.B. Using EXPLAIN before executing the query helps the server prepare the statements used.C. Joins have the potential to cause more server processing if not defined correctly.Answer:C
QUESTION:126Consider the following: mysql> EXPLAIN SELECT DISTINCT City.id,City.name ->FROM City,Country -> WHERE Country.Name IN ('United States','Canada','Mexico') ->ANDCity.CountryCode=Country.Code->ORDERBY*************************** 1. ro*************************** id: 1 select_type: SIMPLE table: City type: ALLpossible_keys: NULLkey: NULL key_len: NULL ref: NULL rows: 4079 Extra: Using temporary; Using filesort***************************2.row***************************id:select_type: SIMPLE table: Country type: eq_ref possible_keys: PRIMARY key: PRIMARYkey_len: 3 ref: world.City.CountryCode rows: 1 Extra: Using where; Distinct Which of thefollowing best describes the meaning of the values in the ref columns?name1
