GitHub user maropu opened a pull request: https://github.com/apache/spark/pull/18576
[SPARK-21351][SQL] Update nullability based on children's output ## What changes were proposed in this pull request? This pr added a new optimizer rule `UpdateNullabilityInAttributeReferences ` to update the nullability that `Filter` changes when having `IsNotNull`. In the master, optimized plans do not respect the nullability when `Filter` has `IsNotNull`. This wrongly generates unnecessary code. For example: ``` scala> val df = Seq((Some(1), Some(2))).toDF("a", "b") scala> val bIsNotNull = df.where($"b" =!= 2).select($"b") scala> val targetQuery = bIsNotNull.distinct scala> val targetQuery.queryExecution.optimizedPlan.output(0).nullable res5: Boolean = true scala> targetQuery.debugCodegen Found 2 WholeStageCodegen subtrees. == Subtree 1 / 2 == *HashAggregate(keys=[b#19], functions=[], output=[b#19]) +- Exchange hashpartitioning(b#19, 200) +- *HashAggregate(keys=[b#19], functions=[], output=[b#19]) +- *Project [_2#16 AS b#19] +- *Filter isnotnull(_2#16) +- LocalTableScan [_1#15, _2#16] Generated code: ... /* 124 */ protected void processNext() throws java.io.IOException { ... /* 132 */ // output the result /* 133 */ /* 134 */ while (agg_mapIter.next()) { /* 135 */ wholestagecodegen_numOutputRows.add(1); /* 136 */ UnsafeRow agg_aggKey = (UnsafeRow) agg_mapIter.getKey(); /* 137 */ UnsafeRow agg_aggBuffer = (UnsafeRow) agg_mapIter.getValue(); /* 138 */ /* 139 */ boolean agg_isNull4 = agg_aggKey.isNullAt(0); /* 140 */ int agg_value4 = agg_isNull4 ? -1 : (agg_aggKey.getInt(0)); /* 141 */ agg_rowWriter1.zeroOutNullBytes(); /* 142 */ // We don't need this NULL check because NULL is filtered out in `$"b" =!=2` /* 143 */ if (agg_isNull4) { /* 144 */ agg_rowWriter1.setNullAt(0); /* 145 */ } else { /* 146 */ agg_rowWriter1.write(0, agg_value4); /* 147 */ } /* 148 */ append(agg_result1); /* 149 */ /* 150 */ if (shouldStop()) return; /* 151 */ } /* 152 */ /* 153 */ agg_mapIter.close(); /* 154 */ if (agg_sorter == null) { /* 155 */ agg_hashMap.free(); /* 156 */ } /* 157 */ } /* 158 */ /* 159 */ } ``` In the line 143, we don't need this NULL check because NULL is filtered out in `$"b" =!=2`. This pr could remove this NULL check; ``` scala> val targetQuery.queryExecution.optimizedPlan.output(0).nullable res5: Boolean = false scala> targetQuery.debugCodegen ... Generated code: ... /* 144 */ protected void processNext() throws java.io.IOException { ... /* 152 */ // output the result /* 153 */ /* 154 */ while (agg_mapIter.next()) { /* 155 */ wholestagecodegen_numOutputRows.add(1); /* 156 */ UnsafeRow agg_aggKey = (UnsafeRow) agg_mapIter.getKey(); /* 157 */ UnsafeRow agg_aggBuffer = (UnsafeRow) agg_mapIter.getValue(); /* 158 */ /* 159 */ int agg_value4 = agg_aggKey.getInt(0); /* 160 */ agg_rowWriter1.write(0, agg_value4); /* 161 */ append(agg_result1); /* 162 */ /* 163 */ if (shouldStop()) return; /* 164 */ } /* 165 */ /* 166 */ agg_mapIter.close(); /* 167 */ if (agg_sorter == null) { /* 168 */ agg_hashMap.free(); /* 169 */ } /* 170 */ } ``` ## How was this patch tested? Added `UpdateNullabilityInAttributeReferencesSuite` for unit tests. You can merge this pull request into a Git repository by running: $ git pull https://github.com/maropu/spark SPARK-21351 Alternatively you can review and apply these changes as the patch at: https://github.com/apache/spark/pull/18576.patch To close this pull request, make a commit to your master/trunk branch with (at least) the following in the commit message: This closes #18576 ---- commit fe5ecff62c0494b8c32c24b83a488bddbbbc6d89 Author: Takeshi Yamamuro <yamam...@apache.org> Date: 2017-06-29T08:50:48Z Update nullability based on children's output ---- --- If your project is set up for it, you can reply to this email and have your reply appear on GitHub as well. If your project does not have this feature enabled and wishes so, or if the feature is enabled but not working, please contact infrastructure at infrastruct...@apache.org or file a JIRA ticket with INFRA. --- --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org