aokolnychyi commented on a change in pull request #26751: [SPARK-30107][SQL]
Expose nested schema pruning to all V2 sources
URL: https://github.com/apache/spark/pull/26751#discussion_r357102082
##########
File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/PushDownUtils.scala
##########
@@ -76,28 +78,46 @@ object PushDownUtils extends PredicateHelper {
* @return the created `ScanConfig`(since column pruning is the last step of
operator pushdown),
* and new output attributes after column pruning.
*/
- // TODO: nested column pruning.
def pruneColumns(
scanBuilder: ScanBuilder,
relation: DataSourceV2Relation,
- exprs: Seq[Expression]): (Scan, Seq[AttributeReference]) = {
+ projects: Seq[NamedExpression],
+ filters: Seq[Expression]): (Scan, Seq[AttributeReference]) = {
scanBuilder match {
+ case r: SupportsPushDownRequiredColumns if
SQLConf.get.nestedSchemaPruningEnabled =>
Review comment:
I don't think there is an API to find out whether a particular `ScanBuilder`
supports nested schema pruning or not. Instead, we have
`SupportsPushDownRequiredColumns` and data sources should use the passed schema
as a reference and prune whatever they can. The flag that we added in this PR
is specific to `FileScanBuilder` and I believe it will complicate the overall
logic if we treat `FileScanBuilder` differently by introducing special branches
or if conditions. Also, we might actually get rid of that flag soon, as
mentioned in DB's
[comment](https://github.com/apache/spark/pull/26751#discussion_r356771927).
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