Query Execution Optimization in Spark SQL

Table 2

Parameters in the cost model.

Parameter	Meaning
X	Size of read/written data
C0	Seeking time and rotation delay time
C1	Time required to transmit 1 MB data
Α	Proportion of non-local data to total data
T	Number of I/O occurrences
|Din|	Size of stage input data
|Dout|	Size of stage output data tr time to read 1 MB data locally
	Time to write 1 MB data locally
tb	Time to transfer 1 MB data over network
B	Buffer size of spark task m task number in stage