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https://issues.apache.org/jira/browse/SPARK-25530?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16715617#comment-16715617
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ASF GitHub Bot commented on SPARK-25530:
----------------------------------------
rdblue commented on a change in pull request #23208: [SPARK-25530][SQL] data
source v2 API refactor (batch write)
URL: https://github.com/apache/spark/pull/23208#discussion_r240394058
##########
File path:
sql/core/src/main/java/org/apache/spark/sql/sources/v2/TableProvider.java
##########
@@ -25,7 +25,10 @@
* The base interface for v2 data sources which don't have a real catalog.
Implementations must
* have a public, 0-arg constructor.
* <p>
- * The major responsibility of this interface is to return a {@link Table} for
read/write.
+ * The major responsibility of this interface is to return a {@link Table} for
read/write. If you
+ * want to allow end-users to write data to non-existing tables via write APIs
in `DataFrameWriter`
+ * with `SaveMode`, you must return a {@link Table} instance even if the table
doesn't exist. The
+ * table schema can be empty in this case.
Review comment:
`SaveMode` is incompatible with the SPIP to standarize behavior that was
voted on and accepted. The save mode in `DataFrameWriter` must be used to
create v2 plans that have well-defined behavior and cannot be passed to
implementations in the final version of the v2 read/write API.
I see no reason to put off removing `SaveMode` from the API. If we remove it
now, we will avoid having more versions of this API that are **fundamentally
broken**. We will avoid more implementations that rely on it, not aware that it
will be removed.
To your point about whether it is safe: the only case where this is actually
used is `SaveMode.Overwrite` and `SaveMode.Append`. To replace those, all that
needs to happen is to define what kind of overwrite should happen here (dynamic
or truncate).
I can supply the logical plan and physical implementation in a follow-up PR
because I already have all this written and waiting to go in. Or, I can add a
PR to merge first if you'd like to have these changes depend on that
implementation.
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> data source v2 API refactor (batch write)
> -----------------------------------------
>
> Key: SPARK-25530
> URL: https://issues.apache.org/jira/browse/SPARK-25530
> Project: Spark
> Issue Type: Sub-task
> Components: SQL
> Affects Versions: 3.0.0
> Reporter: Wenchen Fan
> Priority: Major
>
> Adjust the batch write API to match the read API after refactor
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