chunweilei commented on a change in pull request #1818: [CALCITE-3809]
RexSimplify simplifies nondeterministic function incorrectly
URL: https://github.com/apache/calcite/pull/1818#discussion_r382881401
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File path: core/src/main/java/org/apache/calcite/rex/RexSimplify.java
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@@ -323,7 +323,7 @@ private RexNode simplifyComparison(RexCall e, RexUnknownAs
unknownAs) {
// Simplify "x <op> x"
final RexNode o0 = operands.get(0);
final RexNode o1 = operands.get(1);
- if (o0.equals(o1)) {
+ if (o0.equals(o1) && RexUtil.isDeterministic(o0)) {
Review comment:
Thank you for your clarification. I kind of understand your point. But I am
not convinced. Currently, you can find several places in RexSimplify where
```RexUtil.isDeterministic``` is used[1][2][3], which I think is necessary. Do
they ruin the performance of RexSimplify for valid deterministic cases? I don't
think so.
Now for the 1st question, it can be simplified though non-deterministic
functions exist. For instance, ```AND(rand()=rand(), true, true)``` can be
simplified to ```rand()=rand()```.
[1]https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/rex/RexSimplify.java#L1385
[2]https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/rex/RexSimplify.java#L1542
[3]https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/rex/RexSimplify.java#L2251
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