The BENCHMARK() function returns
the result of the benchmarked expression
the time taken to execute the benchmarked expression
zero, regardless of the parameters
none of the above
You run EXPLAIN on a query and it tells you that the type for one of the tables in the join is ALL . This means that
only one row will be read from the table
all the rows with matching index values will be read from the table
all of the index will be scanned
all of the table will be scanned
You run EXPLAIN on a query and it tells you that the type for one of the tables in the join is eq_ref . This means that
You run EXPLAIN on a query and it tells you that the type for one of the tables in the join is index . This means that
The output of EXPLAIN tells you that MySQL is joining two tables in a suboptimal order. You should
run ANALYZE TABLE on the two tables
force the join order using STRAIGHT JOIN
either a) or b)
neither a) nor b)