godfreyhe commented on a change in pull request #8468:
[FLINK-12399][table][table-planner] Fix FilterableTableSource does not change
after applyPredicate
URL: https://github.com/apache/flink/pull/8468#discussion_r334485078
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File path:
flink-table/flink-table-planner-blink/src/main/scala/org/apache/flink/table/planner/plan/rules/logical/PushProjectIntoTableSourceScanRule.scala
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@@ -67,13 +67,23 @@ class PushProjectIntoTableSourceScanRule extends
RelOptRule(
val relOptTable = scan.getTable.asInstanceOf[FlinkRelOptTable]
val tableSourceTable = relOptTable.unwrap(classOf[TableSourceTable[_]])
val oldTableSource = tableSourceTable.tableSource
- val newTableSource = oldTableSource match {
+ val (newTableSource, isProjectSuccess) = oldTableSource match {
case nested: NestedFieldsProjectableTableSource[_] =>
val nestedFields = RexNodeExtractor.extractRefNestedInputFields(
project.getProjects, usedFields)
- nested.projectNestedFields(usedFields, nestedFields)
+ (nested.projectNestedFields(usedFields, nestedFields), true)
case projecting: ProjectableTableSource[_] =>
- projecting.projectFields(usedFields)
+ (projecting.projectFields(usedFields), true)
+ case nonProjecting: TableSource[_] =>
+ // projection cannot be pushed to TableSource
+ (nonProjecting, false)
+ }
+
+ if (isProjectSuccess
+ &&
newTableSource.explainSource().equals(oldTableSource.explainSource())) {
Review comment:
there is a special case: if the query is `select count(*) from
projectableTableSource`, the `usedFields` to project-pushdown is empty, and the
table source should keep at least one fields to output to count aggregate. if
the projectable table has only one filed, the `explainSource` does not change.
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