twalthr commented on a change in pull request #11527: [FLINK-16035] Updated
Stream/BatchTableEnvironment.java to use Java's Expression DSL
URL: https://github.com/apache/flink/pull/11527#discussion_r401409452
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File path:
flink-table/flink-table-api-scala-bridge/src/main/scala/org/apache/flink/table/api/scala/BatchTableEnvironment.scala
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@@ -164,11 +222,40 @@ trait BatchTableEnvironment extends TableEnvironment {
* Creates a view from the given [[DataSet]] in a given path with specified
field names.
* Registered views can be referenced in SQL queries.
*
+ * There are two modes for mapping original fields to the fields of the
View:
+ *
+ * 1. Reference input fields by name:
+ * All fields in the schema definition are referenced by name
+ * (and possibly renamed using an alias (as). In this mode, fields can be
reordered and
+ * projected out. This mode can be used for any input type, including POJOs.
+ *
+ * Example:
+ *
+ * {{{
+ * val set: DataSet<Tuple2<String, Long>> = ...
+ * tableEnv.createTemporaryView(
+ * "cat.db.myTable",
+ * set,
+ * $"f1", // reorder and use the original field
+ * $"f0" as "name" // reorder and give the original field a better name
+ * )
+ * }}}
+ *
+ * 2. Reference input fields by position:
+ * In this mode, fields are simply renamed. This mode can only be
+ * used if the input type has a defined field order (tuple, case class,
Row) and none of
+ * the `fields` references a field of the input type.
+ *
* Example:
*
* {{{
- * val set: DataSet[(String, Long)] = ...
- * tableEnv.createTemporaryView("cat.db.myTable", set, 'a, 'b)
+ * val set: DataSet<Tuple2<String, Long>> = ...
Review comment:
replace with Scala syntax
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