>I believe you are not allowing the optimizer to generate a different aggregation path (Group Aggregate) because it requires a sort operation. So I think this is not correct.
Yes, this is what I did. I though it is what you were asking? I have not found another way to enforce HashAggregate, so I directly modified the code. Can you eliberate why it is incorrect?
>You may notice that disabling parallelism results in improved cardinality estimation and therefore a better query plan, since the optimizer selects paths based on their cost. If parallelism is disabled, query plan have become more correct.
Can I understand disabling parallelism is a good setup for finding performance issues?
Best regards,
Jinsheng Ba
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