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https://issues.apache.org/jira/browse/FLINK-6124?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15936295#comment-15936295
]
ASF GitHub Bot commented on FLINK-6124:
---------------------------------------
Github user shaoxuan-wang commented on a diff in the pull request:
https://github.com/apache/flink/pull/3593#discussion_r107410682
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/functions/aggfunctions/MaxAggFunctionWithRetract.scala
---
@@ -201,14 +201,22 @@ class DoubleMaxWithRetractAggFunction extends
MaxWithRetractAggFunction[Double]
* Built-in Boolean Max with retraction aggregate function
*/
class BooleanMaxWithRetractAggFunction extends
MaxWithRetractAggFunction[Boolean] {
- override def getInitValue = false
+ override def getInitValue: Boolean = false
override def getValueTypeInfo = BasicTypeInfo.BOOLEAN_TYPE_INFO
}
/**
* Built-in Big Decimal Max with retraction aggregate function
*/
class DecimalMaxWithRetractAggFunction extends
MaxWithRetractAggFunction[BigDecimal] {
- override def getInitValue = BigDecimal.ZERO
+ override def getInitValue: BigDecimal = BigDecimal.ZERO
override def getValueTypeInfo = BasicTypeInfo.BIG_DEC_TYPE_INFO
}
+
+/**
+ * Built-in String Max with retraction aggregate function
+ */
+class StringMaxWithRetractAggFunction extends
MaxWithRetractAggFunction[String] {
+ override def getInitValue: String = ""
--- End diff --
remove ": String"?
> support max/min aggregations for string type
> --------------------------------------------
>
> Key: FLINK-6124
> URL: https://issues.apache.org/jira/browse/FLINK-6124
> Project: Flink
> Issue Type: Improvement
> Components: Table API & SQL
> Reporter: Zhenghua Gao
> Assignee: Zhenghua Gao
> Fix For: 1.3.0
>
>
> Recently when I port some query to Flink SQL, I found currently min/max
> aggregations on string type is not supported and should be added.
> When min/max aggregations are used on string column, return min/max value by
> lexicographically order.
>
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