ORC: Disable predicate pushdown for timestamp type #1069
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rdblue
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May 26, 2020
| (microsFromEpoch % 1_000_000) * 1_000)); | ||
| return Timestamp.from(Instant.ofEpochSecond( | ||
| Math.floorDiv(microsFromEpoch, 1_000_000), | ||
| Math.floorMod(microsFromEpoch, 1_000_000) * 1_000 |
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The previous logic did not correctly handle pre-epoch timestamps and resulted in off by one second error which was the primary cause of failures in #983 (% returns negative values if sign(a)!=sign(b) so it interfered with floorDiv which also has handling for the same). After I fixed this issue, I ran into ORC-611,
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In #983 (comment) we discovered issues with ORC predicate pushdown for timestamp types, where timestamps less than epoch were not handled correctly.
ed91355 fixes this and updates the test case to test for both pre epoch and post epoch values
After fixing this, I also found that ORC column stats for timestamp are only stored to millisecond precisions (with round down) and hence predicates on timestamp types with sub-millisecond literals can potentially be evaluated incorrectly. This is being fixed in https://issues.apache.org/jira/browse/ORC-611. So for the time being, I have disabled pushdown for timestamp types in 63bc62b