private void onMatchRight(RelOptRuleCall call) {
final JoinRelBase topJoin = call.rel(0);
final JoinRelBase bottomJoin = call.rel(1);
final RelNode relC = call.rel(2);
final RelNode relA = bottomJoin.getLeft();
final RelNode relB = bottomJoin.getRight();
final RelOptCluster cluster = topJoin.getCluster();
// topJoin
// / \
// bottomJoin C
// / \
// A B
final int aCount = relA.getRowType().getFieldCount();
final int bCount = relB.getRowType().getFieldCount();
final int cCount = relC.getRowType().getFieldCount();
final BitSet bBitSet = BitSets.range(aCount, aCount + bCount);
// becomes
//
// newTopJoin
// / \
// newBottomJoin B
// / \
// A C
// If either join is not inner, we cannot proceed.
// (Is this too strict?)
if (topJoin.getJoinType() != JoinRelType.INNER
|| bottomJoin.getJoinType() != JoinRelType.INNER) {
return;
}
// Split the condition of topJoin into a conjunction. Each of the
// parts that does not use columns from B can be pushed down.
final List<RexNode> intersecting = new ArrayList<RexNode>();
final List<RexNode> nonIntersecting = new ArrayList<RexNode>();
split(topJoin.getCondition(), bBitSet, intersecting, nonIntersecting);
// If there's nothing to push down, it's not worth proceeding.
if (nonIntersecting.isEmpty()) {
return;
}
// Split the condition of bottomJoin into a conjunction. Each of the
// parts that use columns from B will need to be pulled up.
final List<RexNode> bottomIntersecting = new ArrayList<RexNode>();
final List<RexNode> bottomNonIntersecting = new ArrayList<RexNode>();
split(bottomJoin.getCondition(), bBitSet, bottomIntersecting, bottomNonIntersecting);
// target: | A | C |
// source: | A | B | C |
final Mappings.TargetMapping bottomMapping =
Mappings.createShiftMapping(
aCount + bCount + cCount, 0, 0, aCount, aCount, aCount + bCount, cCount);
List<RexNode> newBottomList = new ArrayList<RexNode>();
new RexPermuteInputsShuttle(bottomMapping, relA, relC)
.visitList(nonIntersecting, newBottomList);
final Mappings.TargetMapping bottomBottomMapping =
Mappings.createShiftMapping(aCount + bCount, 0, 0, aCount);
new RexPermuteInputsShuttle(bottomBottomMapping, relA, relC)
.visitList(bottomNonIntersecting, newBottomList);
final RexBuilder rexBuilder = cluster.getRexBuilder();
RexNode newBottomCondition = RexUtil.composeConjunction(rexBuilder, newBottomList, false);
final JoinRelBase newBottomJoin =
bottomJoin.copy(
bottomJoin.getTraitSet(), newBottomCondition, relA, relC, bottomJoin.getJoinType());
// target: | A | C | B |
// source: | A | B | C |
final Mappings.TargetMapping topMapping =
Mappings.createShiftMapping(
aCount + bCount + cCount,
0,
0,
aCount,
aCount + cCount,
aCount,
bCount,
aCount,
aCount + bCount,
cCount);
List<RexNode> newTopList = new ArrayList<RexNode>();
new RexPermuteInputsShuttle(topMapping, newBottomJoin, relB)
.visitList(intersecting, newTopList);
new RexPermuteInputsShuttle(topMapping, newBottomJoin, relB)
.visitList(bottomIntersecting, newTopList);
RexNode newTopCondition = RexUtil.composeConjunction(rexBuilder, newTopList, false);
@SuppressWarnings("SuspiciousNameCombination")
final JoinRelBase newTopJoin =
topJoin.copy(
topJoin.getTraitSet(), newTopCondition, newBottomJoin, relB, topJoin.getJoinType());
assert !Mappings.isIdentity(topMapping);
final RelNode newProject =
RelFactories.createProject(projectFactory, newTopJoin, Mappings.asList(topMapping));
call.transformTo(newProject);
}
/**
* Creates a relational expression that projects the given fields of the input.
*
* <p>Optimizes if the fields are the identity projection.
*
* @param child Input relational expression
* @param posList Source of each projected field
* @return Relational expression that projects given fields
*/
public static RelNode createProject(final RelNode child, final List<Integer> posList) {
return RelFactories.createProject(RelFactories.DEFAULT_PROJECT_FACTORY, child, posList);
}