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https://issues.apache.org/jira/browse/FLINK-3849?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15929261#comment-15929261
]
ASF GitHub Bot commented on FLINK-3849:
---------------------------------------
Github user KurtYoung commented on a diff in the pull request:
https://github.com/apache/flink/pull/3520#discussion_r106565668
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/plan/rules/common/PushFilterIntoTableSourceScanRuleBase.scala
---
@@ -36,36 +43,34 @@ trait PushFilterIntoTableSourceScanRuleBase {
filterableSource: FilterableTableSource[_],
description: String): Unit = {
- if (filterableSource.isFilterPushedDown) {
- // The rule can get triggered again due to the transformed "scan =>
filter"
- // sequence created by the earlier execution of this rule when we
could not
- // push all the conditions into the scan
- return
- }
+ Preconditions.checkArgument(!filterableSource.isFilterPushedDown)
val program = calc.getProgram
+ val functionCatalog = FunctionCatalog.withBuiltIns
val (predicates, unconvertedRexNodes) =
RexProgramExtractor.extractConjunctiveConditions(
program,
call.builder().getRexBuilder,
- tableSourceTable.tableEnv.getFunctionCatalog)
+ functionCatalog)
if (predicates.isEmpty) {
// no condition can be translated to expression
return
}
- val (newTableSource, remainingPredicates) =
filterableSource.applyPredicate(predicates)
- // trying to apply filter push down, set the flag to true no matter
whether
- // we actually push any filters down.
- newTableSource.setFilterPushedDown(true)
+ val remainingPredicates = new util.LinkedList[Expression]()
+ predicates.foreach(e => remainingPredicates.add(e))
+
+ val newTableSource =
filterableSource.applyPredicate(remainingPredicates)
--- End diff --
I think we don't have to restrict this. If the user for some reason indeed
want to change the predicates which returns back and executed by framework, we
should allow them to do so.
> Add FilterableTableSource interface and translation rule
> --------------------------------------------------------
>
> Key: FLINK-3849
> URL: https://issues.apache.org/jira/browse/FLINK-3849
> Project: Flink
> Issue Type: New Feature
> Components: Table API & SQL
> Reporter: Fabian Hueske
> Assignee: Kurt Young
>
> Add a {{FilterableTableSource}} interface for {{TableSource}} implementations
> which support filter push-down.
> The interface could look as follows
> {code}
> def trait FilterableTableSource {
> // returns unsupported predicate expression
> def setPredicate(predicate: Expression): Expression
> }
> {code}
> In addition we need Calcite rules to push a predicate (or parts of it) into a
> TableScan that refers to a {{FilterableTableSource}}. We might need to tweak
> the cost model as well to push the optimizer in the right direction.
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