rdblue commented on a change in pull request #23606: [SPARK-26666][SQL] Support
DSv2 overwrite and dynamic partition overwrite.
URL: https://github.com/apache/spark/pull/23606#discussion_r256632377
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File path: sql/core/src/main/scala/org/apache/spark/sql/DataFrameWriter.scala
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@@ -253,29 +254,38 @@ final class DataFrameWriter[T] private[sql](ds:
Dataset[T]) {
val dsOptions = new DataSourceOptions(options.asJava)
provider.getTable(dsOptions) match {
case table: SupportsBatchWrite =>
- if (mode == SaveMode.Append) {
- val relation = DataSourceV2Relation.create(table, options)
- runCommand(df.sparkSession, "save") {
- AppendData.byName(relation, df.logicalPlan)
- }
- } else {
- val writeBuilder = table.newWriteBuilder(dsOptions)
- .withQueryId(UUID.randomUUID().toString)
- .withInputDataSchema(df.logicalPlan.schema)
- writeBuilder match {
- case s: SupportsSaveMode =>
- val write = s.mode(mode).buildForBatch()
- // It can only return null with `SupportsSaveMode`. We can
clean it up after
- // removing `SupportsSaveMode`.
- if (write != null) {
- runCommand(df.sparkSession, "save") {
- WriteToDataSourceV2(write, df.logicalPlan)
+ lazy val relation = DataSourceV2Relation.create(table, options)
+ mode match {
+ case SaveMode.Append =>
+ runCommand(df.sparkSession, "save") {
+ AppendData.byName(relation, df.logicalPlan)
+ }
+
+ case SaveMode.Overwrite =>
+ // truncate the table
+ runCommand(df.sparkSession, "save") {
+ OverwriteByExpression.byName(relation, df.logicalPlan,
Literal(true))
Review comment:
@cloud-fan, I think that `Literal(true)` is better than using `Nil`. This
translates directly to an `AlwaysTrue` filter, which has obvious behavior:
`DELETE FROM table WHERE true`.
Using `Nil` or no filters to signal that all rows should be deleted is not
obvious and requires more documentation for the contract with implementations.
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