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TableScan -- Relations with Column Pruning

TableScan is the <> of <> with support for <>, i.e. can eliminate unneeded columns before producing an RDD containing all of its tuples as Row objects.

[[contract]] [source, scala]


package org.apache.spark.sql.sources

trait PrunedScan { def buildScan(): RDD[Row] }


.TableScan Contract [cols="1m,2",options="header",width="100%"] |=== | Property | Description

| buildScan | [[buildScan]] Building distributed data scan with column pruning

In other words, buildScan creates a RDD[Row] to represent a distributed data scan (i.e. scanning over data in a relation).

Used exclusively when DataSourceStrategy execution planning strategy is requested to linkplan a LogicalRelation with a TableScan. |===

[[implementations]] NOTE: KafkaRelation is the one and only known implementation of the <> in Spark SQL.


Last update: 2020-11-13