Re: Do SPM baselines retain DOP?

On 2018/08/03 15:51, Dominic Brooks wrote:

> Some old thoughts:
> https://orastory.wordpress.com/2012/03/09/sql-patch-iii-plus-parallel-baselines/

Hey Dominic,

Perhaps it's my misunderstanding of SPM (likely) or maybe a bug (hmmm...also likely), but I was able to successfully create a baseline that preserved not only the "forced" parallelism, but the DOP as well. I did use a slightly different method than you describe in your blog post though. I first loaded the original plan into SPM using SQL_ID, executed my parallel query with a session-specific PARALLEL_DEGREE_LIMIE, then loaded that plan into SPM using it's SQL_ID and PLAN_HASH_VALUE but with the original SQL's SQL_HANDLE from DBA_SQL_PLAN_BASELINES. I then altered the new baseline to be fixed and optionally dropped the original baseline.

It works, but I haven't seen anywhere it's documented that the parallel plan sticks with the new baseline and, more importantly, the degree of parallelism. It may help the optimizer in that the original SQL in my case is doing four full table scans.

Thanks!
Rich

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