[ https://issues.apache.org/jira/browse/SPARK-16594?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Apache Spark reassigned SPARK-16594: ------------------------------------ Assignee: Apache Spark > Physical Plan Differences when Table Scan Having Duplicate Columns > ------------------------------------------------------------------ > > Key: SPARK-16594 > URL: https://issues.apache.org/jira/browse/SPARK-16594 > Project: Spark > Issue Type: Improvement > Components: SQL > Affects Versions: 2.0.0 > Reporter: Xiao Li > Assignee: Apache Spark > > Currently, we keep two implementations for planning scans over data sources. > There is one difference between two implementation when deciding whether a > `Project` is needed or not. > - Data Source Table Scan: > https://github.com/apache/spark/blob/b1e5281c5cb429e338c3719c13c0b93078d7312a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/DataSourceStrategy.scala#L322-L395 > - `SELECT b, b FROM oneToTenPruned`: **_Add `ProjectExec`._** > - Hive Table Scan and In-memory Table Scan: > https://github.com/apache/spark/blob/865ec32dd997e63aea01a871d1c7b4947f43c111/sql/core/src/main/scala/org/apache/spark/sql/execution/SparkPlanner.scala#L71-L99 > > - `SELECT b, b FROM oneToTenPruned`: **_No `ProjectExec` is added._** > **Note.** When alias is being used, we will always add `ProjectExec` in all > the scan types. > - `SELECT b as alias_b, b FROM oneToTenPruned`: **_Add `ProjectExec`._** > Because selecting the same column twice without adding `alias` is very weird, > no clue why the code needs to behave differently here. -- This message was sent by Atlassian JIRA (v6.3.4#6332) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org