CannotPlanException after "CROSS JOIN UNNEST" - apache-flink

Question

When I create a VIEW as a result of "CROSS JOIN UNNEST" and then use the condition in the WHERE clause of the VIEW, it throws an exception "org.apache.calcite.plan.RelOptPlanner$CannotPlanException".
Why am I getting this exception and how should I handle it the right way?
The following is the test code in which an error occurs.
it should "filter with object_key" in {
tEnv.executeSql(
s"""CREATE TABLE s3_put_event (
| Records ARRAY<
| ROW<
| s3 ROW<
| bucket ROW<name STRING>,
| object ROW<key STRING, size BIGINT>
| >
| >
| >
|) WITH (
| 'connector' = 'datagen',
| 'number-of-rows' = '3',
| 'rows-per-second' = '1',
| 'fields.Records.element.s3.bucket.name.length' = '8',
| 'fields.Records.element.s3.object.key.length' = '15',
| 'fields.Records.element.s3.object.size.min' = '1',
| 'fields.Records.element.s3.object.size.max' = '1000'
|)
|""".stripMargin
)
tEnv.executeSql(
s"""CREATE TEMPORARY VIEW s3_objects AS
|SELECT object_key, bucket_name
|FROM (
| SELECT
| r.s3.bucket.name AS bucket_name,
| r.s3.object.key AS object_key,
| r.s3.object.size AS object_size
| FROM s3_put_event
| CROSS JOIN UNNEST(s3_put_event.Records) AS r(s3)
|) rs
|WHERE object_size > 0
|""".stripMargin
)
tEnv.executeSql(
s"""CREATE TEMPORARY VIEW filtered_s3_objects AS
|SELECT bucket_name, object_key
|FROM s3_objects
|WHERE object_key > ''
|""".stripMargin)
val result = tEnv.sqlQuery("SELECT * FROM filtered_s3_objects")
tEnv.toChangelogStream(result).print()
env.execute()
}
If I remove the condition object_key > '' in the "filtered_s3_objects" VIEW, and do it in the "s3_objects" VIEW, no exception is thrown.
However, my actual query is complicated, so it is not easy to move the condition of the WHERE clause like this. It's hard to use especially if I need to separate the output stream.

Answer 1

I'm not sure that you can use a CROSS JOIN UNNEST on an array with a nested hierarchy (given that you have a ROW in your ARRAY). Either way, could you file a Jira ticket for this? https://issues.apache.org/jira/projects/FLINK/issues/