com.hazelcast.org.apache.calcite.rel.rules.JoinAssociateRule Maven / Gradle / Ivy
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package com.hazelcast.org.apache.calcite.rel.rules;
import com.hazelcast.org.apache.calcite.plan.RelOptCluster;
import com.hazelcast.org.apache.calcite.plan.RelOptRule;
import com.hazelcast.org.apache.calcite.plan.RelOptRuleCall;
import com.hazelcast.org.apache.calcite.plan.volcano.RelSubset;
import com.hazelcast.org.apache.calcite.rel.RelNode;
import com.hazelcast.org.apache.calcite.rel.core.Join;
import com.hazelcast.org.apache.calcite.rel.core.JoinRelType;
import com.hazelcast.org.apache.calcite.rel.core.RelFactories;
import com.hazelcast.org.apache.calcite.rex.RexBuilder;
import com.hazelcast.org.apache.calcite.rex.RexNode;
import com.hazelcast.org.apache.calcite.rex.RexPermuteInputsShuttle;
import com.hazelcast.org.apache.calcite.rex.RexUtil;
import com.hazelcast.org.apache.calcite.tools.RelBuilderFactory;
import com.hazelcast.org.apache.calcite.util.ImmutableBitSet;
import com.hazelcast.org.apache.calcite.util.mapping.Mappings;
import java.util.ArrayList;
import java.util.List;
/**
* Planner rule that changes a join based on the associativity rule.
*
* ((a JOIN b) JOIN c) → (a JOIN (b JOIN c))
*
* We do not need a rule to convert (a JOIN (b JOIN c)) →
* ((a JOIN b) JOIN c) because we have
* {@link JoinCommuteRule}.
*
* @see JoinCommuteRule
*/
public class JoinAssociateRule extends RelOptRule implements TransformationRule {
//~ Static fields/initializers ---------------------------------------------
/** The singleton. */
public static final JoinAssociateRule INSTANCE =
new JoinAssociateRule(RelFactories.LOGICAL_BUILDER);
//~ Constructors -----------------------------------------------------------
/**
* Creates a JoinAssociateRule.
*/
public JoinAssociateRule(RelBuilderFactory relBuilderFactory) {
super(
operand(Join.class,
operand(Join.class, any()),
operand(RelSubset.class, any())),
relBuilderFactory, null);
}
//~ Methods ----------------------------------------------------------------
public void onMatch(final RelOptRuleCall call) {
final Join topJoin = call.rel(0);
final Join bottomJoin = call.rel(1);
final RelNode relA = bottomJoin.getLeft();
final RelNode relB = bottomJoin.getRight();
final RelSubset relC = call.rel(2);
final RelOptCluster cluster = topJoin.getCluster();
final RexBuilder rexBuilder = cluster.getRexBuilder();
if (relC.getConvention() != relA.getConvention()) {
// relC could have any trait-set. But if we're matching say
// EnumerableConvention, we're only interested in enumerable subsets.
return;
}
// topJoin
// / \
// bottomJoin C
// / \
// A B
final int aCount = relA.getRowType().getFieldCount();
final int bCount = relB.getRowType().getFieldCount();
final int cCount = relC.getRowType().getFieldCount();
final ImmutableBitSet aBitSet = ImmutableBitSet.range(0, aCount);
final ImmutableBitSet bBitSet =
ImmutableBitSet.range(aCount, aCount + bCount);
if (!topJoin.getSystemFieldList().isEmpty()) {
// FIXME Enable this rule for joins with system fields
return;
}
// If either join is not inner, we cannot proceed.
// (Is this too strict?)
if (topJoin.getJoinType() != JoinRelType.INNER
|| bottomJoin.getJoinType() != JoinRelType.INNER) {
return;
}
// Goal is to transform to
//
// newTopJoin
// / \
// A newBottomJoin
// / \
// B C
// Split the condition of topJoin and bottomJoin into a conjunctions. A
// condition can be pushed down if it does not use columns from A.
final List top = new ArrayList<>();
final List bottom = new ArrayList<>();
JoinPushThroughJoinRule.split(topJoin.getCondition(), aBitSet, top, bottom);
JoinPushThroughJoinRule.split(bottomJoin.getCondition(), aBitSet, top,
bottom);
// Mapping for moving conditions from topJoin or bottomJoin to
// newBottomJoin.
// target: | B | C |
// source: | A | B | C |
final Mappings.TargetMapping bottomMapping =
Mappings.createShiftMapping(
aCount + bCount + cCount,
0, aCount, bCount,
bCount, aCount + bCount, cCount);
final List newBottomList = new ArrayList<>();
new RexPermuteInputsShuttle(bottomMapping, relB, relC)
.visitList(bottom, newBottomList);
RexNode newBottomCondition =
RexUtil.composeConjunction(rexBuilder, newBottomList);
final Join newBottomJoin =
bottomJoin.copy(bottomJoin.getTraitSet(), newBottomCondition, relB,
relC, JoinRelType.INNER, false);
// Condition for newTopJoin consists of pieces from bottomJoin and topJoin.
// Field ordinals do not need to be changed.
RexNode newTopCondition = RexUtil.composeConjunction(rexBuilder, top);
@SuppressWarnings("SuspiciousNameCombination")
final Join newTopJoin =
topJoin.copy(topJoin.getTraitSet(), newTopCondition, relA,
newBottomJoin, JoinRelType.INNER, false);
call.transformTo(newTopJoin);
}
}