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https://issues.apache.org/jira/browse/FLINK-5220?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15725760#comment-15725760
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ASF GitHub Bot commented on FLINK-5220:
---------------------------------------
Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/2923#discussion_r91083093
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/api/table/plan/rules/dataSet/PushProjectIntoBatchTableSourceScanRule.scala
---
@@ -0,0 +1,95 @@
+/*
+ * 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.api.table.plan.rules.dataSet
+
+import org.apache.calcite.plan.{RelOptRule, RelOptRuleCall}
+import org.apache.calcite.plan.RelOptRule.{none, operand}
+import org.apache.calcite.rex.{RexProgram, RexUtil}
+import
org.apache.flink.api.table.plan.nodes.dataset.{BatchTableSourceScan,
DataSetCalc}
+import org.apache.flink.api.table.plan.rules.util.DataSetCalcConverter._
+import org.apache.flink.api.table.sources.{BatchTableSource,
ProjectableTableSource}
+import scala.collection.JavaConverters._
+
+/**
+ * This rule is responsible for push project into BatchTableSourceScan
node
+ */
+class PushProjectIntoBatchTableSourceScanRule extends RelOptRule(
+ operand(classOf[DataSetCalc],
+ operand(classOf[BatchTableSourceScan], none)),
+ "PushProjectIntoBatchTableSourceScanRule") {
+
+ override def matches(call: RelOptRuleCall) = {
+ val scan: BatchTableSourceScan =
call.rel(1).asInstanceOf[BatchTableSourceScan]
+ scan.tableSource match {
+ case _: ProjectableTableSource[_] => true
+ case _ => false
+ }
+ }
+
+ override def onMatch(call: RelOptRuleCall) {
+ val calc: DataSetCalc = call.rel(0).asInstanceOf[DataSetCalc]
+ val scan: BatchTableSourceScan =
call.rel(1).asInstanceOf[BatchTableSourceScan]
+
+ val usedFields: Array[Int] = extractRefInputFields(calc)
+
+ // if no fields can be projected, there is no need to transform subtree
+ if (scan.tableSource.getNumberOfFields == usedFields.length) {
+ return
+ }
+
+ val originTableSource =
scan.tableSource.asInstanceOf[ProjectableTableSource[_]]
+
+ val newTableSource = originTableSource.projectFields(usedFields)
+
+ val newScan = new BatchTableSourceScan(
+ scan.getCluster,
+ scan.getTraitSet,
+ scan.getTable,
+ newTableSource.asInstanceOf[BatchTableSource[_]])
+
+ val (newProjectExprs, newConditionExpr) = rewriteCalcExprs(calc,
usedFields)
+
+ // if project merely returns its input and doesn't exist filter,
remove datasetCalc nodes
+ val newProjectExprsList = newProjectExprs.asJava
+ if (RexUtil.isIdentity(newProjectExprsList, newScan.getRowType)
--- End diff --
Can be checked as `RexProgram.isTrivial()`
> Flink SQL projection pushdown
> -----------------------------
>
> Key: FLINK-5220
> URL: https://issues.apache.org/jira/browse/FLINK-5220
> Project: Flink
> Issue Type: Improvement
> Components: Table API & SQL
> Reporter: zhangjing
> Assignee: zhangjing
>
> The jira is to do projection pushdown optimization. Please go forward to the
> the design document for more details.
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