[GitHub] [calcite] liyafan82 commented on a change in pull request #2105: [CALCITE-4159] Simplify always-true expressions (such as LIKE '%') to TRUE

[GitBox <gi...@apache.org>]

liyafan82 commented on a change in pull request #2105:
URL: https://github.com/apache/calcite/pull/2105#discussion_r472066153



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File path: core/src/main/java/org/apache/calcite/plan/RelOptPredicateList.java
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@@ -180,4 +203,27 @@ public RelOptPredicateList shift(RexBuilder rexBuilder, int offset) {
         RexUtil.shift(leftInferredPredicates, offset),
         RexUtil.shift(rightInferredPredicates, offset));
   }
+
+  /** Returns whether an expression is effectively NOT NULL due to an
+   * {@code e IS NOT NULL} condition in this predicate list. */
+  public boolean isEffectivelyNotNull(RexNode e) {
+    if (!e.getType().isNullable()) {
+      return true;
+    }
+    for (RexNode p : pulledUpPredicates) {
+      if (p.getKind() == SqlKind.IS_NOT_NULL
+          && ((RexCall) p).getOperands().get(0).equals(e)) {
+        return true;
+      }
+    }
+    if (SqlKind.COMPARISON.contains(e.getKind())) {
+      // A comparison with a literal, such as 'ref < 10', is not null if 'ref'
+      // is not null.
+      RexCall call = (RexCall) e;
+      if (call.getOperands().get(1) instanceof RexLiteral) {
+        return isEffectivelyNotNull(call.getOperands().get(0));

Review comment:
       do we also need to consider cases such as '10 > ref' here?




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