[jira] [Created] (SPARK-23500) Filters on named_structs could be pushed into scans

["Henry Robinson (JIRA)" <ji...@apache.org>]

Henry Robinson created SPARK-23500:
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             Summary: Filters on named_structs could be pushed into scans
                 Key: SPARK-23500
                 URL: https://issues.apache.org/jira/browse/SPARK-23500
             Project: Spark
          Issue Type: Improvement
          Components: SQL
    Affects Versions: 2.3.0
            Reporter: Henry Robinson


Simple filters on dataframes joined with {{joinWith()}} are missing an opportunity to get pushed into the scan because they're written in terms of {{named_struct}} that could be removed by the optimizer.

Given the following simple query over two dataframes:
{code:java}
scala> val df = spark.read.parquet("one_million")
df: org.apache.spark.sql.DataFrame = [id: bigint, id2: bigint]

scala> val df2 = spark.read.parquet("one_million")
df2: org.apache.spark.sql.DataFrame = [id: bigint, id2: bigint]

scala> df.joinWith(df2, df2.col("id") === df.col("id2")).filter("_2.id > 30").explain
== Physical Plan ==
*(2) BroadcastHashJoin [_1#94.id2], [_2#95.id], Inner, BuildRight
:- *(2) Project [named_struct(id, id#0L, id2, id2#1L) AS _1#94]
: +- *(2) FileScan parquet [id#0L,id2#1L] Batched: true, Format: Parquet, Location: InMemoryFileIndex[file:/Users/henry/src/spark/one_million], PartitionFilters: [], PushedFilters: [], ReadSchema: struct<id:bigint,id2:bigint>
+- BroadcastExchange HashedRelationBroadcastMode(List(input[0, struct<id:bigint,id2:bigint>, false].id))
+- *(1) Project [named_struct(id, id#90L, id2, id2#91L) AS _2#95]
+- *(1) Filter (named_struct(id, id#90L, id2, id2#91L).id > 30)
+- *(1) FileScan parquet [id#90L,id2#91L] Batched: true, Format: Parquet, Location: InMemoryFileIndex[file:/Users/henry/src/spark/one_million], PartitionFilters: [], PushedFilters: [], ReadSchema: struct<id:bigint,id2:bigint>
{code}

Using {{joinWith}} means that the filter is placed on a {{named_struct}}, and is then pushed down. When the filter is just above the scan, the wrapping-and-projection of {{named_struct(id...).id}} is a no-op and could be removed. Then the filter can be pushed down to Parquet.




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