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https://issues.apache.org/jira/browse/FLINK-3849?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15923433#comment-15923433
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ASF GitHub Bot commented on FLINK-3849:
---------------------------------------
Github user godfreyhe commented on a diff in the pull request:
https://github.com/apache/flink/pull/3520#discussion_r105812230
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/plan/rules/common/PushFilterIntoTableSourceScanRuleBase.scala
---
@@ -0,0 +1,97 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.table.plan.rules.common
+
+import org.apache.calcite.plan.RelOptRuleCall
+import org.apache.calcite.rel.core.{Calc, TableScan}
+import org.apache.calcite.rex.RexProgram
+import org.apache.flink.table.plan.nodes.dataset.DataSetCalc
+import org.apache.flink.table.plan.schema.TableSourceTable
+import org.apache.flink.table.plan.util.RexProgramExtractor
+import org.apache.flink.table.sources.FilterableTableSource
+
+trait PushFilterIntoTableSourceScanRuleBase {
+
+ private[flink] def pushFilterIntoScan(
+ call: RelOptRuleCall,
+ calc: Calc,
+ scan: TableScan,
+ tableSourceTable: TableSourceTable[_],
+ 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
+ }
+
+ val program = calc.getProgram
+ val (predicates, unconvertedRexNodes) =
+ RexProgramExtractor.extractConjunctiveConditions(
+ program,
+ call.builder().getRexBuilder,
+ tableSourceTable.tableEnv.getFunctionCatalog)
+ if (predicates.isEmpty) {
+ // no condition can be translated to expression
+ return
+ }
+
+ // trying to apply filter push down, set the flag to true no matter
whether
+ // we actually push any filters down.
+ filterableSource.setFilterPushedDown(true)
+ val remainingPredicates = filterableSource.applyPredicate(predicates)
+
+ // check whether framework still need to do a filter
+ val relBuilder = call.builder()
+ val remainingCondition = {
+ if (remainingPredicates.length > 0 || unconvertedRexNodes.length >
0) {
--- End diff --
nonEmpty is better than length > 0, i think
> 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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