twalthr commented on code in PR #28403:
URL: https://github.com/apache/flink/pull/28403#discussion_r3412663375
##########
flink-table/flink-table-planner/src/main/scala/org/apache/flink/table/planner/plan/optimize/program/FlinkChangelogModeInferenceProgram.scala:
##########
@@ -114,9 +114,24 @@ class FlinkChangelogModeInferenceProgram extends
FlinkOptimizeProgram[StreamOpti
// step4: sanity check and return non-empty root
if (finalRoot.isEmpty) {
- val plan = FlinkRelOptUtil.toString(root, withChangelogTraits = true)
- throw new TableException(
- "Can't generate a valid execution plan for the given query:\n" + plan)
+ val errorMessage =
+ if (containsUpdates(rootWithModifyKindSet)) {
+ // Point at the failing node and its inputs instead of dumping the
whole plan.
+ val conflict = new
StringBuilder(describeChangelog(rootWithModifyKindSet))
+ rootWithModifyKindSet.getInputs.foreach(
+ input => conflict.append("\n +-
").append(describeChangelog(input)))
+ "Can't generate a valid execution plan for the given query.\n\n" +
+ "There is a changelog mismatch between two operators. One produces
an upsert " +
+ "changelog (UPDATE_AFTER without UPDATE_BEFORE). The other
requires a retract " +
+ "changelog (UPDATE_BEFORE and UPDATE_AFTER), for example a sink
without a primary " +
Review Comment:
Just declaring a PRIMARY KEY won't always solve the problem. I would
generalize the message to something like:
```
In such cases, ensure that the sink is able to digest upserts where the
PRIMARY KEY serves as the upsert key, or make the input produce UPDATE_BEFORE.
```
##########
flink-table/flink-table-planner/src/main/scala/org/apache/flink/table/planner/plan/optimize/program/FlinkChangelogModeInferenceProgram.scala:
##########
@@ -1604,6 +1619,21 @@ class FlinkChangelogModeInferenceProgram extends
FlinkOptimizeProgram[StreamOpti
modifyKindSetTrait.modifyKindSet
}
+ /** Whether the node or any node in its input subtree produces UPDATE
changes. */
+ private def containsUpdates(rel: RelNode): Boolean =
+ getModifyKindSet(rel).contains(ModifyKind.UPDATE) ||
+ rel.getInputs.exists(input => containsUpdates(input))
+
+ /** Renders a node's type and changelog mode, for example
"Sink(changelogMode=[NONE])". */
Review Comment:
> Sink(changelogMode=[NONE])
I always found this `NONE` very confusing. For this error message, could we
instead print the expected mode by the sink?
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