Why not parallelism

博雄 胡 190 Reputation points
2024-06-25T07:28:54.6033333+00:00
select * from yieldtransit

cost threshold for parallelism run_value = 1

max degree of parallelism run_value = 0

StatementSubTreeCost = 42.1767

sqlplan.xml

SQL Server
SQL Server
A family of Microsoft relational database management and analysis systems for e-commerce, line-of-business, and data warehousing solutions.
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  1. Olaf Helper 43,166 Reputation points
    2024-06-25T07:50:02.08+00:00

    There is no JOIN, no WHERE, only a query as full table scan.

    What for parallelism on what do you expect?

    If it would be a partioned table, then maybe.

    1 person found this answer helpful.

  2. Erland Sommarskog 106.8K Reputation points
    2024-06-25T21:43:35.3333333+00:00

    The final operator cannot have parallelism. There is not much point in having a parallel scan and a Gather Streams operator. Also, the major part of the execution time in this case is receiving the data in the client.

    But if you try something like

    SELECT col, COUNT(*)
    FROM  yieldtransit
    GROUP BY col
    

    This is query is likely to have parallelism, since there is now more work to do.

    1 person found this answer helpful.