libenchao commented on code in PR #2761:
URL: https://github.com/apache/calcite/pull/2761#discussion_r877011436
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core/src/main/java/org/apache/calcite/rel/rules/FilterJoinRule.java:
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@@ -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);
Review Comment:
never mind, I've changed it. (In most cases, I also prefer no side-effect
methods, they are more readable and maintainable)
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