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https://issues.apache.org/jira/browse/FLINK-8203?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16313207#comment-16313207
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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_r159880719
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/api/StreamTableEnvironment.scala
---
@@ -492,11 +509,16 @@ abstract class StreamTableEnvironment(
throw new TableException(
"The proctime attribute can only be defined once in a table
schema.")
} else {
- // check that proctime is only appended
- if (idx < fieldTypes.length) {
- throw new TableException(
- "The proctime attribute can only be appended to the table
schema and not replace " +
- "an existing field. Please move it to the end of the
schema.")
+ // if the fields are referenced by position,
+ // it is only possible to append the time attribute at the end
+ if (isRefByPos) {
+
+ // check that proctime is only appended
+ if (idx < fieldTypes.length) {
+ throw new TableException(
+ "The proctime attribute can only be appended to the table
schema and not replace " +
+ "an existing field. Please move it to the end of the
schema.")
+ }
}
proctime = Some(idx, name)
--- End diff --
should we also check that the name of the proctime attribute is not in the
fields of the input type?
> 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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