chunweilei commented on code in PR #2761:
URL: https://github.com/apache/calcite/pull/2761#discussion_r877681035
##########
core/src/main/java/org/apache/calcite/rel/rules/FilterJoinRule.java:
##########
@@ -225,6 +232,105 @@ protected void perform(RelOptRuleCall call, @Nullable
Filter filter,
call.transformTo(relBuilder.build());
}
+ /**
+ * Infer more equal conditions for the Join Condition.
+ *
+ * <p> For example, in {@code SELECT * FROM T1, T2, T3 WHERE T1.id = T3.id
AND T2.id = T3.id},
+ * we can infer {@code T1.id = T2.id} for the first Join node from second
Join node's condition:
+ * {@code T1.id = T3.id AND T2.id = T3.id}.
+ *
+ * <p>For the above SQL, the second Join's condition is {@code T1.id = T3.id
AND T2.id = T3.id}.
+ * After inference, the final condition would be: {@code T1.id = T2.id AND
T1.id = T3.id}, the
+ * {@code T1.id = T2.id} can be further pushed into LHS.
+ *
+ * @param rexNodes the Join condition
+ * @param join the Join node
+ */
+ protected void inferJoinEqualConditions(List<RexNode> rexNodes, Join join) {
+ final List<Set<Integer>> equalSets = new ArrayList<>();
+ final List<RexNode> result = new ArrayList<>(rexNodes.size());
+ for (RexNode rexNode : rexNodes) {
+ if (rexNode.isA(SqlKind.EQUALS)) {
+ final RexNode op1 = ((RexCall) rexNode).getOperands().get(0);
+ final RexNode op2 = ((RexCall) rexNode).getOperands().get(1);
+ if (op1 instanceof RexInputRef && op2 instanceof RexInputRef) {
+ final RexInputRef in1 = (RexInputRef) op1;
+ final RexInputRef in2 = (RexInputRef) op2;
+ Set<Integer> set = null;
+ for (Set<Integer> s : equalSets) {
+ if (s.contains(in1.getIndex()) || s.contains(in2.getIndex())) {
+ set = s;
+ break;
+ }
+ }
+ if (set == null) {
+ set = new LinkedHashSet<>(); // to make the result deterministic
+ equalSets.add(set);
+ }
+ set.add(in1.getIndex());
+ set.add(in2.getIndex());
+ } else {
+ result.add(rexNode);
+ }
+ } else {
+ result.add(rexNode);
+ }
+ }
+
+ boolean needOptimize = false;
+ for (Set<Integer> set : equalSets) {
+ if (set.size() > 2) {
+ needOptimize = true;
+ break;
+ }
+ }
+ if (!needOptimize) {
+ // keep the conditions unchanged.
+ return;
+ }
+
+ final RexBuilder rexBuilder = join.getCluster().getRexBuilder();
+ for (Set<Integer> set : equalSets) {
+ final List<Integer> leftSet = new ArrayList<>();
+ final List<Integer> rightSet = new ArrayList<>();
+ for (int i : set) {
+ if (i < join.getLeft().getRowType().getFieldCount()) {
+ leftSet.add(i);
Review Comment:
`final int leftRowCount = join.getLeft().getRowType().getFieldCount();` can
be moved to out of the loop.
##########
core/src/main/java/org/apache/calcite/rel/rules/FilterJoinRule.java:
##########
@@ -225,6 +232,132 @@ protected void perform(RelOptRuleCall call, @Nullable
Filter filter,
call.transformTo(relBuilder.build());
}
+ /**
+ * Infer more equal conditions for the Join Condition.
+ *
+ * <p> For example, in {@code SELECT * FROM T1, T2, T3 WHERE T1.id = T3.id
AND T2.id = T3.id},
+ * we can infer {@code T1.id = T2.id} for the first Join node from second
Join node's condition:
+ * {@code T1.id = T3.id AND T2.id = T3.id}.
+ *
+ * <p>For the above SQL, the second Join's condition is {@code T1.id = T3.id
AND T2.id = T3.id}.
+ * After inference, the final condition would be: {@code T1.id = T2.id AND
T1.id = T3.id}, the
+ * {@code T1.id = T2.id} can be further pushed into LHS.
+ *
+ * @param rexNodes the Join condition
+ * @param join the Join node
+ * @return the newly inferred conditions
+ */
+ protected List<RexNode> inferJoinEqualConditions(List<RexNode> rexNodes,
Join join) {
+ final List<RexNode> result = new ArrayList<>(rexNodes.size());
+ final List<Set<Integer>> equalSets = splitEqualSets(rexNodes, result);
+
+ boolean needOptimize = false;
+ for (Set<Integer> set : equalSets) {
+ if (set.size() > 2) {
+ needOptimize = true;
+ break;
+ }
+ }
+ if (!needOptimize) {
+ // keep the conditions unchanged.
+ return rexNodes;
+ }
+
+ result.addAll(constructConditionFromEqualSets(join, equalSets));
+ return result;
+ }
+
+ /**
+ * Split out the equal sets.
+ *
+ * @param rexNodes the original conditions
+ * @param leftNodes where the conditions not feasible for equal sets are put
+ * @return the equal sets
+ */
+ private List<Set<Integer>> splitEqualSets(List<RexNode> rexNodes,
List<RexNode> leftNodes) {
+ final List<Set<Integer>> equalSets = new ArrayList<>();
+ for (RexNode rexNode : rexNodes) {
+ if (rexNode.isA(SqlKind.EQUALS)) {
+ final RexNode op1 = ((RexCall) rexNode).getOperands().get(0);
+ final RexNode op2 = ((RexCall) rexNode).getOperands().get(1);
+ if (op1 instanceof RexInputRef && op2 instanceof RexInputRef) {
+ final RexInputRef in1 = (RexInputRef) op1;
+ final RexInputRef in2 = (RexInputRef) op2;
+ Set<Integer> set = null;
+ for (Set<Integer> s : equalSets) {
+ if (s.contains(in1.getIndex()) || s.contains(in2.getIndex())) {
+ set = s;
+ break;
+ }
+ }
+ if (set == null) {
+ set = new LinkedHashSet<>(); // to make the result deterministic
+ equalSets.add(set);
+ }
+ set.add(in1.getIndex());
+ set.add(in2.getIndex());
+ } else {
+ leftNodes.add(rexNode);
+ }
+ } else {
+ leftNodes.add(rexNode);
+ }
+ }
+
+ return equalSets;
+ }
+
+ /**
+ * Construct new conditions from the equal sets.
+ *
+ * @param join the original {@link Join} node
+ * @param equalSets the equal sets
+ * @return the newly constructed conditions from equal sets
+ */
Review Comment:
Construct new conditions -> Constructs new equal conditions?
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