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Oct 28, 2015 at 08:16 AM

Parallelization <=> serialization, when parallelization does not work?



The following are preventing parallel execution as far as I know:

Scalar parameters or variables used within procedure

SQL not assigned to variable

Has imperative and loop logic
Has DDL operations
operations that serialize (CASE )

In the following example temp1 and temp 2 can run parallel with Intra-Query Parallelism as well? temp3 will need the result of temp1 and temp2 so I quess no Inter-query Parallelism but what about Intra-Query Parallelism,in this point does HANA drop from the parallelization phase or temp 3 will be also run parallel just had to wait the result of temp1 and temp2?

What about itab_all_bp this will not run Intra-Query Parallelism because of the Case?

What are the other commands which serialize other than the Case?

Waiting for your valuable input.



Hana_parallel.png (141.4 kB)