# \[Breaking Change\] Hail 0.2 import\_bgen should be passed a min\_partitions parameter

**URL:** <https://discuss.hail.is/t/breaking-change-hail-0-2-import-bgen-should-be-passed-a-min-partitions-parameter/566>\
**Category:** Updates\
**Created:** [July 12, 2018, 12:46am UTC](https://discuss.hail.is/t/breaking-change-hail-0-2-import-bgen-should-be-passed-a-min-partitions-parameter/566 "2018-07-12T00:46:28Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![danking](https://yyz2.discourse-cdn.com/flex036/user_avatar/discuss.hail.is/danking/32/43_2.png) [@danking](https://discuss.hail.is/u/danking)\
**Post date:** [July 12, 2018, 12:46am UTC](https://discuss.hail.is/t/breaking-change-hail-0-2-import-bgen-should-be-passed-a-min-partitions-parameter/566/1 "2018-07-12T00:46:28Z")

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Previously, some Spark heuristics chose a reasonable number of partitions for `import_bgen`. This logic has been removed while we improve bgen performance (we may add the logic back in before 0.2 release). In the meantime, you will notice that `import_bgen` uses far fewer partitions than is appropriate. You can use the `min_partitions` argument to force a higher number of partitions. For the UKBB dataset, try using around 18,000 partitions.