# Query plan possible over-parallelized, cause duplicates

**URL:** <https://community.dremio.com/t/query-plan-possible-over-parallelized-cause-duplicates/1781>\
**Category:** Uncategorized\
**Created:** [September 6, 2018, 4:51pm UTC](https://community.dremio.com/t/query-plan-possible-over-parallelized-cause-duplicates/1781 "2018-09-06T16:51:22Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![dli16](https://avatars.discourse-cdn.com/v4/letter/d/c5a1d2/32.png) [@dli16](https://community.dremio.com/u/dli16)\
**Post date:** [September 6, 2018, 4:51pm UTC](https://community.dremio.com/t/query-plan-possible-over-parallelized-cause-duplicates/1781/1 "2018-09-06T16:51:22Z")

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We have seen duplicates on a dataset in which the count got doubled. When checking on the query profile, the planning use Parallelism of 2 to read the same reflection which I assume is the cause of dups. Later when we query the dataset again, the parallelism showed ‘1’ and the dups were gone.

Attached please find the query profile. Thank you.  
[12c386d8-d697-4c7c-bbfa-5164c247f93d.zip](https://us1.discourse-cdn.com/flex020/uploads/dremio/original/1X/3af3325164e0e73140bfb2a36833f453203c4ea1.zip) (25.5 KB)

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**Author:** ![dli16](https://avatars.discourse-cdn.com/v4/letter/d/c5a1d2/32.png) [@dli16](https://community.dremio.com/u/dli16)\
**Post date:** [September 18, 2018, 1:34pm UTC](https://community.dremio.com/t/query-plan-possible-over-parallelized-cause-duplicates/1781/2 "2018-09-18T13:34:06Z")

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Hello, can you provide some insight about how Dremio determines the parallelism number for a specific job? From my observation, the number seems to be nondeterministic for the same query.

Thank you in advance for helping me out.