I receive the following error when trying to use the LISTAGG function in
Table API.
java.lang.RuntimeException: SingleValueAggFunction received more than one
element.
at GroupAggsHandler$1460.accumulate(Unknown Source)
at
org.apache.flink.table.runtime.operators.aggregate.GroupAggFunction.processElement(GroupAggFunction.java:158)
at
org.apache.flink.table.runtime.operators.aggregate.GroupAggFunction.processElement(GroupAggFunction.java:43)
at
org.apache.flink.streaming.api.operators.KeyedProcessOperator.processElement(KeyedProcessOperator.java:85)
at
org.apache.flink.streaming.runtime.io.StreamOneInputProcessor.processElement(StreamOneInputProcessor.java:164)
at
org.apache.flink.streaming.runtime.io.StreamOneInputProcessor.processInput(StreamOneInputProcessor.java:143)
at
org.apache.flink.streaming.runtime.tasks.StreamTask.processInput(StreamTask.java:279)
at
org.apache.flink.streaming.runtime.tasks.StreamTask.run(StreamTask.java:301)
at
org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:406)
at org.apache.flink.runtime.taskmanager.Task.doRun(Task.java:705)
at org.apache.flink.runtime.taskmanager.Task.run(Task.java:530)
at java.lang.Thread.run(Thread.java:748)
This is my query,
SELECT node.nid,
(SELECT LISTAGG(DISTINCT(TDC.name)) FROM M_TermNode TNC JOIN M_TermData TDC
ON TNC.tid = TDC.tid WHERE node.nid = TNC.nid AND TDC.vid = (SELECT
Vocab.vid from M_Vocabulary Vocab where Vocab.`module` = 'extra_fields')) AS
characteristics
FROM node
The above query looks slightly complex but essentially boils down to a group
by on TDC.vid. This may return more than one value for TDC.name which needs
to be concatenated into the same string.
I have tried removing the DISTINCT clause inside LISTAGG but to no avail.
The same query works on a MySQL DB with GROUP_CONCAT instead of LISTAGG.
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