Github user hsuanyi commented on the pull request:
https://github.com/apache/drill/pull/461#issuecomment-210144139
In the background, Chun, Rahul and Jinfeng have done some experiments:
1. Functional-wise: If Hive uses storage-based impersonation, when a user
does "Show Tables" on Hive (without going through DRILL), this user will see
the tables which might not be under his/her permission. So from the aspect, the
behavior of Drill matches Hive with respect to visibility of tables displayed.
2. Performance-wise:
For INFORMATION_SCHEMA query against a hive instance with 1000 tables
(impersonation was off),
we got 38 seconds when the patch is not applied (non bulk load), and 8
seconds is when the patch is applied (bulk load).
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