Github user gatorsmile commented on a diff in the pull request:
https://github.com/apache/spark/pull/21590#discussion_r197620455
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/jdbc/JDBCOptions.scala
---
@@ -109,6 +134,20 @@ class JDBCOptions(
s"When reading JDBC data sources, users need to specify all or none
for the following " +
s"options: '$JDBC_PARTITION_COLUMN', '$JDBC_LOWER_BOUND',
'$JDBC_UPPER_BOUND', " +
s"and '$JDBC_NUM_PARTITIONS'")
+
+ require(!(query.isDefined && partitionColumn.isDefined),
+ s"""
+ |Options '$JDBC_QUERY_STRING' and '$JDBC_PARTITION_COLUMN' can not
be specified together.
+ |Please define the query using `$JDBC_TABLE_NAME` option instead
and make sure to qualify
+ |the partition columns using the supplied subquery alias to resolve
any ambiguity.
+ |Example :
+ |spark.read.format("jdbc")
+ | .option("dbtable", "(select c1, c2 from t1) as subq")
+ | .option("partitionColumn", "subq.c1"
+ | .load()
--- End diff --
Great! Please add them to the doc as I mentioned above?
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