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https://issues.apache.org/jira/browse/FLINK-8203?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16312192#comment-16312192
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ASF GitHub Bot commented on FLINK-8203:
---------------------------------------
Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/5132#discussion_r159770375
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/api/TableEnvironment.scala
---
@@ -791,92 +824,109 @@ abstract class TableEnvironment(val config:
TableConfig) {
* Returns field names and field positions for a given
[[TypeInformation]] and [[Array]] of
* [[Expression]]. It does not handle time attributes but considers
them in indices.
*
+ * @param isReferenceByPosition schema mode see
[[isReferenceByPosition()]]
* @param inputType The [[TypeInformation]] against which the
[[Expression]]s are evaluated.
* @param exprs The expressions that define the field names.
* @tparam A The type of the TypeInformation.
* @return A tuple of two arrays holding the field names and
corresponding field positions.
*/
- protected[flink] def getFieldInfo[A](
+ protected def getFieldInfo[A](
+ isReferenceByPosition: Boolean,
inputType: TypeInformation[A],
exprs: Array[Expression])
: (Array[String], Array[Int]) = {
TableEnvironment.validateType(inputType)
+ def referenceByName(name: String, ct: CompositeType[_]): Option[(Int,
String)] = {
--- End diff --
if we change the return type to `Option[Int]`, we can use it also for the
`Alias` cases.
For example for `PojoTypeInfo`:
```
case (UnresolvedFieldReference(name: String)) =>
referenceByName(name, p).map((_, name))
case Alias(UnresolvedFieldReference(origName), name: String, _) =>
referenceByName(origName, p).map((_, name))
```
> Make schema definition of DataStream/DataSet to Table conversion more flexible
> ------------------------------------------------------------------------------
>
> Key: FLINK-8203
> URL: https://issues.apache.org/jira/browse/FLINK-8203
> Project: Flink
> Issue Type: Bug
> Components: Table API & SQL
> Affects Versions: 1.4.0, 1.5.0
> Reporter: Fabian Hueske
> Assignee: Timo Walther
>
> When converting or registering a {{DataStream}} or {{DataSet}} as {{Table}},
> the schema of the table can be defined (by default it is extracted from the
> {{TypeInformation}}.
> The schema needs to be manually specified to select (project) fields, rename
> fields, or define time attributes. Right now, there are several limitations
> how the fields can be defined that also depend on the type of the
> {{DataStream}} / {{DataSet}}. Types with explicit field ordering (e.g.,
> tuples, case classes, Row) require schema definition based on the position of
> fields. Pojo types which have no fixed order of fields, require to refer to
> fields by name. Moreover, there are several restrictions on how time
> attributes can be defined, e.g., event time attribute must replace an
> existing field or be appended and proctime attributes must be appended.
> I think we can make the schema definition more flexible and provide two modes:
> 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. Moreover, we can define
> proctime and eventtime attributes at arbitrary positions using arbitrary
> names (except those that existing the result schema). This mode can be used
> for any input type, including POJOs. This mode is used if all field
> references exist in the input type.
> 2. Reference input fields by position: Field references might not refer to
> existing fields in the input type. In this mode, fields are simply renamed.
> Event-time attributes can replace the field on their position in the input
> data (if it is of correct type) or be appended at the end. Proctime
> attributes must be appended at the end. This mode can only be used if the
> input type has a defined field order (tuple, case class, Row).
> We need to add more tests the check for all combinations of input types and
> schema definition modes.
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