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https://issues.apache.org/jira/browse/BEAM-8365?focusedWorklogId=328827&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-328827
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ASF GitHub Bot logged work on BEAM-8365:
----------------------------------------
Author: ASF GitHub Bot
Created on: 15/Oct/19 23:10
Start Date: 15/Oct/19 23:10
Worklog Time Spent: 10m
Work Description: 11moon11 commented on pull request #9764: [BEAM-8365]
Project push-down for TestTableProvider
URL: https://github.com/apache/beam/pull/9764#discussion_r335213030
##########
File path:
sdks/java/extensions/sql/src/main/java/org/apache/beam/sdk/extensions/sql/impl/rule/BeamIOPushDownRule.java
##########
@@ -0,0 +1,236 @@
+/*
+ * 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.beam.sdk.extensions.sql.impl.rule;
+
+import java.util.ArrayDeque;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Queue;
+import java.util.Set;
+import java.util.stream.Collectors;
+import org.apache.beam.sdk.extensions.sql.impl.rel.BeamIOSourceRel;
+import org.apache.beam.sdk.extensions.sql.impl.utils.CalciteUtils;
+import org.apache.beam.sdk.extensions.sql.meta.BeamSqlTable;
+import org.apache.beam.sdk.schemas.FieldAccessDescriptor;
+import org.apache.beam.sdk.schemas.FieldAccessDescriptor.FieldDescriptor;
+import org.apache.beam.sdk.schemas.Schema;
+import org.apache.beam.sdk.schemas.utils.SelectHelpers;
+import
org.apache.beam.vendor.calcite.v1_20_0.com.google.common.collect.ImmutableList;
+import
org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.plan.RelOptRule;
+import
org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.plan.RelOptRuleCall;
+import org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rel.RelNode;
+import org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rel.core.Calc;
+import
org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rel.core.RelFactories;
+import
org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rel.type.RelDataType;
+import
org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rel.type.RelDataTypeField;
+import
org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rel.type.RelRecordType;
+import org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rex.RexCall;
+import
org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rex.RexInputRef;
+import
org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rex.RexLocalRef;
+import org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rex.RexNode;
+import
org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rex.RexProgram;
+import
org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.tools.RelBuilder;
+import
org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.tools.RelBuilderFactory;
+import org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.util.Pair;
+import
org.apache.beam.vendor.guava.v26_0_jre.com.google.common.annotations.VisibleForTesting;
+
+public class BeamIOPushDownRule extends RelOptRule {
+ // ~ Static fields/initializers ---------------------------------------------
+
+ public static final BeamIOPushDownRule INSTANCE =
+ new BeamIOPushDownRule(RelFactories.LOGICAL_BUILDER);
+
+ // ~ Constructors -----------------------------------------------------------
+
+ public BeamIOPushDownRule(RelBuilderFactory relBuilderFactory) {
+ super(operand(Calc.class, operand(BeamIOSourceRel.class, any())),
relBuilderFactory, null);
+ }
+
+ // ~ Methods ----------------------------------------------------------------
+
+ @Override
+ public void onMatch(RelOptRuleCall call) {
+ final Calc calc = call.rel(0);
+ final BeamIOSourceRel ioSourceRel = call.rel(1);
+ final BeamSqlTable beamSqlTable = ioSourceRel.getBeamSqlTable();
+ final RexProgram program = calc.getProgram();
+ final Pair<ImmutableList<RexNode>, ImmutableList<RexNode>> projectFilter =
program.split();
+ final RelDataType calcInputRowType = program.getInputRowType();
+ RelBuilder relBuilder = call.builder();
+
+ if (!beamSqlTable.supportsProjects()) {
+ return;
+ }
+
+ // Nested rows are not supported at the moment
+ for (RelDataTypeField field : ioSourceRel.getRowType().getFieldList()) {
+ if (field.getType() instanceof RelRecordType) {
+ return;
+ }
+ }
+
+ // Find all input refs used by projects
+ Set<String> usedFields = new HashSet<>();
+ for (RexNode project : projectFilter.left) {
+ findUtilizedInputRefs(calcInputRowType, project, usedFields);
+ }
+
+ // Check if the calc can be dropped
+ if (isProjectRenameOnlyProgram(program)) {
+ call.transformTo(ioSourceRel.copy(calc.getRowType(), new
ArrayList<>(usedFields)));
+ return;
+ }
+
+ // Find all input refs used by filters
+ for (RexNode filter : projectFilter.right) {
+ findUtilizedInputRefs(calcInputRowType, filter, usedFields);
+ }
+
+ // TODO: will need to be updated for predicate push-down
+ if (usedFields.size()
+ == ioSourceRel.getRowType().getFieldCount()) { // Already most optimal
case
+ return;
+ }
+
+ FieldAccessDescriptor resolved =
+
FieldAccessDescriptor.withFieldNames(usedFields).resolve(beamSqlTable.getSchema());
+ Schema newSchema =
+
SelectHelpers.getOutputSchema(ioSourceRel.getBeamSqlTable().getSchema(),
resolved);
+ RelDataType calcInputType =
+ CalciteUtils.toCalciteRowType(newSchema,
ioSourceRel.getCluster().getTypeFactory());
+
+ BeamIOSourceRel newIoSourceRel = ioSourceRel.copy(calcInputType, new
ArrayList<>(usedFields));
+ relBuilder.push(newIoSourceRel);
+
+ List<RexNode> newProjects = new ArrayList<>();
+ List<RexNode> newFilter = new ArrayList<>();
+ // Ex: let's say the original fields are (number before each element is
the index):
+ // {0:unused1, 1:id, 2:name, 3:unused2},
+ // where only 'id' and 'name' are being used. Then the new calcInputType
should be as follows:
+ // {0:id, 1:name}.
+ // A mapping list will contain 2 entries: {0:1, 1:2},
+ // showing how used field names map to the original fields.
+ List<Integer> mapping =
+ resolved.getFieldsAccessed().stream()
+ .map(FieldDescriptor::getFieldId)
+ .collect(Collectors.toList());
+
+ // Map filters to new RexInputRef
+ for (RexNode filter : projectFilter.right) {
+ newFilter.add(reMapRexNodeToNewInputs(filter, mapping));
+ }
+ // Map projects to new RexInputRef
+ for (RexNode project : projectFilter.left) {
+ newProjects.add(reMapRexNodeToNewInputs(project, mapping));
+ }
+
+ relBuilder.filter(newFilter);
+ relBuilder.project(newProjects, calc.getRowType().getFieldNames()); //
Preserve named projects
+
+ RelNode result = relBuilder.build();
+
+ call.transformTo(result);
+ }
+
+ /**
+ * Given a {@code RexNode}, find all {@code RexInputRef}s a node or it's
children nodes use.
+ *
+ * @param inputRowType {@code RelDataType} used for looking up names of
{@code RexInputRef}.
+ * @param startNode A node to start at.
+ * @param usedFields Names of {@code RexInputRef}s are added to this list.
+ */
+ @VisibleForTesting
+ void findUtilizedInputRefs(RelDataType inputRowType, RexNode startNode,
Set<String> usedFields) {
+ Queue<RexNode> prerequisites = new ArrayDeque<>();
+ prerequisites.add(startNode);
+
+ // Assuming there are no cyclic nodes, traverse dependency tree until all
RexInputRefs are found
+ while (!prerequisites.isEmpty()) {
+ RexNode node = prerequisites.poll();
+
+ if (node instanceof RexCall) { // Composite expression, example:
"=($t11, $t12)"
+ RexCall compositeNode = (RexCall) node;
+
+ // Expression from example above contains 2 operands: $t11, $t12
+ prerequisites.addAll(compositeNode.getOperands());
+ } else if (node instanceof RexInputRef) { // Input reference
+ // Find a field in an inputRowType for the input reference
+ int inputFieldIndex = ((RexInputRef) node).getIndex();
+ RelDataTypeField field =
inputRowType.getFieldList().get(inputFieldIndex);
+
+ // If we have not seen it before - add it to the list (hash set)
+ usedFields.add(field.getName());
+ }
Review comment:
Here is a list of node types present in Calcite:
`RexCall`, `RexFieldAccess`, `RexLiteral`, `RexRangeRef`, `RexVariable`.
-
[RexFieldAccess](https://calcite.apache.org/apidocs/org/apache/calcite/rex/RexFieldAccess.html)
can only be found in queries like:
```
example the expression emp.deptno in
SELECT ename
FROM dept
WHERE EXISTS (
SELECT NULL
FROM emp
WHERE emp.deptno = dept.deptno
AND gender = 'F')
```
which does not happen in `BeamIOSourceRel -> Calc`, but somewhere in a
`Join` as far as I can tell.
- RexLiteral does not contain any information about fields used by the Calc,
so we can ignore it.
-
[RexRangeRef](https://calcite.apache.org/apidocs/org/apache/calcite/rex/RexRangeRef.html)
only used internally by calcite.
```
Regular rex trees do not contain this construct.
```
-
[RexVariable](https://calcite.apache.org/apidocs/org/apache/calcite/rex/RexVariable.html)
has following sub-classes:
-
[RexCorrelVariable](https://calcite.apache.org/apidocs/org/apache/calcite/rex/RexCorrelVariable.html)
Correlating variables are introduced when performing nested loop joins, so
should not be relevant at this stage.
-
[RexSlot](https://calcite.apache.org/apidocs/org/apache/calcite/rex/RexSlot.html)
is extended by `RexInputRef`, and `RexLocalRef` (substituted by
`RexProgram#split`).
-
[RexDynamicParam](https://calcite.apache.org/apidocs/org/apache/calcite/rex/RexDynamicParam.html)
May need to be handled, but have not seen it appear in any existent tests.
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Issue Time Tracking
-------------------
Worklog Id: (was: 328827)
Time Spent: 5h 10m (was: 5h)
> Add project push-down capability to IO APIs
> -------------------------------------------
>
> Key: BEAM-8365
> URL: https://issues.apache.org/jira/browse/BEAM-8365
> Project: Beam
> Issue Type: New Feature
> Components: dsl-sql
> Reporter: Kirill Kozlov
> Assignee: Kirill Kozlov
> Priority: Major
> Time Spent: 5h 10m
> Remaining Estimate: 0h
>
> * InMemoryTable should implement a following method:
> {code:java}
> public PCollection<Row> buildIOReader(
> PBegin begin, BeamSqlTableFilter filters, List<String> fieldNames);{code}
> Which should return a `PCollection` with fields specified in `fieldNames`
> list.
> * Create a rule to push fields used by a Calc (in projects and in a
> condition) down into TestTable IO.
> * Updating that same Calc (from previous step) to have a proper input and
> output schemes, remove unused fields.
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