ryan-johnson-cloudera opened a new pull request, #4452:
URL: https://github.com/apache/hive/pull/4452
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### What changes were proposed in this pull request?
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1. Before this PR, the code for computing BETWEEN selectivity estimation
assumed that the BETWEEN call consisted of 3 operands: InputRef, LiteralLeft,
and LiteralRight. However there is a forth boolean operand (in position 0) that
was not accounted for. Due to this, the conditions for entering the
computeBetweenPredicateSelectivity function were incorrectly failing. This PR
fixes this issue and accounts for the forth boolean operand in the conditions
to enter the computeBetweenPredicateSelectivity function.
2. For the BETWEEN case, NULL values are not being accounted for in the
selectivity estimation, this PR fixes the selectivity estimation to account for
NULLs.
3. The forth boolean operand, which was initially not accounted for,
represents whether the BETWEEN case is a traditional BETWEEN or a NOT BETWEEN.
Code was added to invert the selectivity if the boolean operand suggests that
the BETWEEN case was a NOT BETWEEN.
### Why are the changes needed?
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1. Since the forth boolean operand (in position 0) is not accounted for, the
checks to enter the computeBetweenPredicateSelectivity function always fail and
selectivity is never calculated for BETWEEN calls.
2. The BETWEEN selectivity estimation was partially incorrect as it did not
consider NULL values in its calculation.
3. If the boolean operand suggests that the BETWEEN case was a NOT BETWEEN,
then the selectivity should be inverted. Before this PR, this boolean operand
was not considered in the BETWEEN selectivity estimation.
### Does this PR introduce _any_ user-facing change?
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No
### Is the change a dependency upgrade?
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No
### How was this patch tested?
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Unit tests are found in `TestFilterSelectivityEstimator.java` file.
`mvn test -Dtest.output.overwrite -Dtest=TestMiniLlapLocalCliDriver
-Dqfile=stats_histogram_null.q -pl itests/qtest -Pitests`
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