[FLINK-17321] Support for casting collection types.

• Type: Sub-task
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 1.15.0
• Component/s: Table SQL / Runtime
• Labels: pull-request-available
• Assignee: Sergey Nuyanzin
• Reporter: Dawid Wysakowicz
• Created: 22/Apr/20 07:57
• Updated: 19/Jan/22 09:49
• Resolved: 18/Jan/22 13:34

Description

Casts of collection types are not supported yet.
E.g. query: "SELECT cast (a as ARRAY<double>) FROM (VALUES (array[3, 2, 1])) AS T(a)"

fails with:

org.apache.flink.table.planner.codegen.CodeGenException: Unsupported cast from 'ARRAY<INT NOT NULL> NOT NULL' to 'ARRAY<DOUBLE> NOT NULL'.

	at org.apache.flink.table.planner.codegen.calls.ScalarOperatorGens$.generateCast(ScalarOperatorGens.scala:1284)
	at org.apache.flink.table.planner.codegen.ExprCodeGenerator.generateCallExpression(ExprCodeGenerator.scala:691)
	at org.apache.flink.table.planner.codegen.ExprCodeGenerator.visitCall(ExprCodeGenerator.scala:486)
	at org.apache.flink.table.planner.codegen.ExprCodeGenerator.visitCall(ExprCodeGenerator.scala:52)
	at org.apache.calcite.rex.RexCall.accept(RexCall.java:288)
	at org.apache.flink.table.planner.codegen.ExprCodeGenerator.generateExpression(ExprCodeGenerator.scala:132)
	at org.apache.flink.table.planner.codegen.CalcCodeGenerator$$anonfun$5.apply(CalcCodeGenerator.scala:152)
	at org.apache.flink.table.planner.codegen.CalcCodeGenerator$$anonfun$5.apply(CalcCodeGenerator.scala:152)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
	at scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59)
	at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:48)
	at scala.collection.TraversableLike$class.map(TraversableLike.scala:234)
	at scala.collection.AbstractTraversable.map(Traversable.scala:104)
	at org.apache.flink.table.planner.codegen.CalcCodeGenerator$.produceProjectionCode$1(CalcCodeGenerator.scala:152)
	at org.apache.flink.table.planner.codegen.CalcCodeGenerator$.generateProcessCode(CalcCodeGenerator.scala:179)
	at org.apache.flink.table.planner.codegen.CalcCodeGenerator$.generateCalcOperator(CalcCodeGenerator.scala:49)
	at org.apache.flink.table.planner.plan.nodes.physical.batch.BatchExecCalc.translateToPlanInternal(BatchExecCalc.scala:62)
	at org.apache.flink.table.planner.plan.nodes.physical.batch.BatchExecCalc.translateToPlanInternal(BatchExecCalc.scala:38)
	at org.apache.flink.table.planner.plan.nodes.exec.ExecNode$class.translateToPlan(ExecNode.scala:58)
	at org.apache.flink.table.planner.plan.nodes.physical.batch.BatchExecCalcBase.translateToPlan(BatchExecCalcBase.scala:42)
	at org.apache.flink.table.planner.plan.nodes.physical.batch.BatchExecSink.translateToTransformation(BatchExecSink.scala:131)
	at org.apache.flink.table.planner.plan.nodes.physical.batch.BatchExecSink.translateToPlanInternal(BatchExecSink.scala:97)
	at org.apache.flink.table.planner.plan.nodes.physical.batch.BatchExecSink.translateToPlanInternal(BatchExecSink.scala:49)
	at org.apache.flink.table.planner.plan.nodes.exec.ExecNode$class.translateToPlan(ExecNode.scala:58)
	at org.apache.flink.table.planner.plan.nodes.physical.batch.BatchExecSink.translateToPlan(BatchExecSink.scala:49)
	at org.apache.flink.table.planner.delegation.BatchPlanner$$anonfun$translateToPlan$1.apply(BatchPlanner.scala:72)
	at org.apache.flink.table.planner.delegation.BatchPlanner$$anonfun$translateToPlan$1.apply(BatchPlanner.scala:71)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
	at scala.collection.Iterator$class.foreach(Iterator.scala:891)
	at scala.collection.AbstractIterator.foreach(Iterator.scala:1334)
	at scala.collection.IterableLike$class.foreach(IterableLike.scala:72)
	at scala.collection.AbstractIterable.foreach(Iterable.scala:54)
	at scala.collection.TraversableLike$class.map(TraversableLike.scala:234)
	at scala.collection.AbstractTraversable.map(Traversable.scala:104)
	at org.apache.flink.table.planner.delegation.BatchPlanner.translateToPlan(BatchPlanner.scala:71)
	at org.apache.flink.table.planner.delegation.PlannerBase.translate(PlannerBase.scala:153)
...

Similar behaviour can be observed for MULTISET, MAP, ROW

Issue Links

• duplicates: FLINK-24204 Failed to insert nested types using value construction functions
• is related to: FLINK-19659 Array type supports equals and not_equals operator when element types are different but castable
• links to: GitHub Pull Request #18287