Parallelism in Index Scan
Parallelism in Index Scan
By : Kasim Wirama, MCDBA
Previous articles, I post some information about internal of parallelism. Now take a look parallelism in index scan. Is that bad if you have parallelism in index scan? Not really, I think. If the query needs to return thousands of records, this index scan will be beneficial to query performance when it is compensated by fast I/O subsystem and SQL Server has some available threads to process data pages. The more process threads and supported by fast I/O, the faster execution time will be.
Now focus on parallelism in index scan. The good thing parallelism in index scan is that SQL Server is able to do load balancing among threads when those threads has different speed in processing rows, so it is expected that slow threads would not dominate total execution time.