spark-instrumented-optimizer/sql/catalyst
Dongjoon Hyun 257391497b [SPARK-26975][SQL] Support nested-column pruning over limit/sample/repartition
## What changes were proposed in this pull request?

As [SPARK-26958](https://github.com/apache/spark/pull/23862/files) benchmark shows, nested-column pruning has limitations. This PR aims to remove the limitations on `limit/repartition/sample`. Here, repartition means `Repartition`, not `RepartitionByExpression`.

**PREPARATION**
```scala
scala> spark.range(100).map(x => (x, (x, s"$x" * 100))).toDF("col1", "col2").write.mode("overwrite").save("/tmp/p")
scala> sql("set spark.sql.optimizer.nestedSchemaPruning.enabled=true")
scala> spark.read.parquet("/tmp/p").createOrReplaceTempView("t")
```

**BEFORE**
```scala
scala> sql("SELECT col2._1 FROM (SELECT col2 FROM t LIMIT 1000000)").explain
== Physical Plan ==
CollectLimit 1000000
+- *(1) Project [col2#22._1 AS _1#28L]
   +- *(1) FileScan parquet [col2#22] Batched: false, DataFilters: [], Format: Parquet, Location: InMemoryFileIndex[file:/tmp/p], PartitionFilters: [], PushedFilters: [], ReadSchema: struct<col2:struct<_1:bigint>>

scala> sql("SELECT col2._1 FROM (SELECT /*+ REPARTITION(1) */ col2 FROM t)").explain
== Physical Plan ==
*(2) Project [col2#22._1 AS _1#33L]
+- Exchange RoundRobinPartitioning(1)
   +- *(1) Project [col2#22]
      +- *(1) FileScan parquet [col2#22] Batched: false, DataFilters: [], Format: Parquet, Location: InMemoryFileIndex[file:/tmp/p], PartitionFilters: [], PushedFilters: [], ReadSchema: struct<col2:struct<_1:bigint,_2:string>>
```

**AFTER**
```scala
scala> sql("SELECT col2._1 FROM (SELECT /*+ REPARTITION(1) */ col2 FROM t)").explain
== Physical Plan ==
Exchange RoundRobinPartitioning(1)
+- *(1) Project [col2#5._1 AS _1#11L]
   +- *(1) FileScan parquet [col2#5] Batched: false, DataFilters: [], Format: Parquet, Location: InMemoryFileIndex[file:/tmp/p], PartitionFilters: [], PushedFilters: [], ReadSchema: struct<col2:struct<_1:bigint>>
```

This supercedes https://github.com/apache/spark/pull/23542 and https://github.com/apache/spark/pull/23873 .

## How was this patch tested?

Pass the Jenkins with a newly added test suite.

Closes #23964 from dongjoon-hyun/SPARK-26975-ALIAS.

Lead-authored-by: Dongjoon Hyun <dhyun@apple.com>
Co-authored-by: DB Tsai <d_tsai@apple.com>
Co-authored-by: Liang-Chi Hsieh <viirya@gmail.com>
Co-authored-by: Takeshi Yamamuro <yamamuro@apache.org>
Co-authored-by: Dongjoon Hyun <dongjoon@apache.org>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>
2019-03-19 20:24:22 -07:00
..
benchmarks [SPARK-25657][SQL][TEST] Refactor HashBenchmark to use main method 2018-10-07 09:49:37 -07:00
src [SPARK-26975][SQL] Support nested-column pruning over limit/sample/repartition 2019-03-19 20:24:22 -07:00
pom.xml [SPARK-27016][SQL][BUILD] Treat all antlr warnings as errors while generating parser from the sql grammar file. 2019-03-03 10:02:25 -06:00