[GitHub] [calcite] rubenada commented on a change in pull request #2253: [CALCITE-4385] Simplifies AND/OR condition that has common expressions, extract and eliminate/merge them as much as possible (Jiatao Tao)

[GitBox]

rubenada commented on a change in pull request #2253:
URL: https://github.com/apache/calcite/pull/2253#discussion_r522040936



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File path: core/src/main/java/org/apache/calcite/rex/RexSimplify.java
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@@ -1689,6 +1690,123 @@ RexNode simplifyAnd2ForUnknownAsFalse(List<RexNode> 
terms,
     }
   }
 
+  /**
+   * <p>Simplifies AND/OR condition that has common expressions,
+   * extract and eliminate/merge them as much as possible.</p>
+   * <ul>
+   * <li>(a OR b) AND (a OR b OR c OR d) =&gt; (a OR b)
+   * <li>(a OR b OR c OR d) AND (a OR b OR e OR f) =&gt; (a OR b) OR ((c OR d) 
AND (e OR f))
+
+   * <li>(a AND b) OR (a AND b AND c) =&gt; (a AND b)
+   * <li>(a AND b AND c AND d) OR (a AND b AND e AND f) =&gt;
+   * (a AND b) AND ((c AND d) OR (e AND f))
+   * </ul>
+   * <p> The difference between {@link #simplifyAnd} is that {@link 
#simplifyAnd} mainly
+   * simplifies expressions whose answer can be determined without evaluating 
both sides,
+   * like: FALSE AND (xxx) =&gt; FALSE</p>
+   */
+  public RexNode eliminateCommonExprInCondition(RexNode call) {

Review comment:
       I uderstand  @Aaaaaaron , thanks for the explanation.
   IMHO the current PR as it is (a new method that is not used, apart from the 
unit test), does not make much sense. I would prefer to see a PR combining 1 & 
2 from my previous comment (i.e. this new method, used by a certain join rule, 
so that we can see it "in action").
   Having said that, if people think otherwise, I would not oppose to merging 
the current PR as it is.




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