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new cc61c5f5cfa [fix](nereids) simplify self compare exclude non-foldable
expression (#47054)
cc61c5f5cfa is described below
commit cc61c5f5cfa92e44cd0b2ea5939d5a04831f8638
Author: yujun <[email protected]>
AuthorDate: Thu Jan 16 15:54:16 2025 +0800
[fix](nereids) simplify self compare exclude non-foldable expression
(#47054)
### What problem does this PR solve?
#46905 add an rewrite expression rule to simplify self comparison, for
example: `a = a` will evaluate to `TRUE`.
But if `a` is non-foldable, it shouldn't simplify. for example: function
`random` is non-foldable, then `random(1, 10) = random(1, 10)` cannot
evaluate to `TRUE`.
What's more, if an expression is non-deterministic, but if it's
foldable, then self comparison also can fold it too. for example:
function `user` is foldable and non-deterministic, then `user() =
user()` can still simplify to `TRUE`.
---
.../nereids/rules/expression/rules/SimplifySelfComparison.java | 7 ++++++-
.../nereids/trees/expressions/functions/ExpressionTrait.java | 9 ++++++++-
.../rules/expression/rules/SimplifySelfComparisonTest.java | 8 ++++++++
3 files changed, 22 insertions(+), 2 deletions(-)
diff --git
a/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/rules/SimplifySelfComparison.java
b/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/rules/SimplifySelfComparison.java
index dbd89964710..76e93c44203 100644
---
a/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/rules/SimplifySelfComparison.java
+++
b/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/rules/SimplifySelfComparison.java
@@ -54,7 +54,12 @@ public class SimplifySelfComparison implements
ExpressionPatternRuleFactory {
private Expression rewrite(ComparisonPredicate comparison) {
Expression left = comparison.left();
- if (left.equals(comparison.right())) {
+ // expression maybe non-deterministic, but if it's foldable, then it
still can simplify self comparison.
+ // for example, function `user()`, `current_timestamp()` are foldable
and non-deterministic,
+ // then `user() = user()` and `current_timestamp() =
current_timestamp()` can simplify to `TRUE`.
+ // function `random` is not foldable and non-deterministic,
+ // then `random(1, 10) = random(1, 10)` cann't simplify to `TRUE`
+ if (!left.containsNonfoldable() && left.equals(comparison.right())) {
if (comparison instanceof EqualTo
|| comparison instanceof GreaterThanEqual
|| comparison instanceof LessThanEqual) {
diff --git
a/fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/functions/ExpressionTrait.java
b/fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/functions/ExpressionTrait.java
index daaab359e84..6e33f2a5e11 100644
---
a/fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/functions/ExpressionTrait.java
+++
b/fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/functions/ExpressionTrait.java
@@ -77,6 +77,13 @@ public interface ExpressionTrait extends
TreeNode<Expression> {
return true;
}
+ /**
+ * Identify the expression is containing non-foldable expr or not
+ */
+ default boolean containsNonfoldable() {
+ return anyMatch(expr -> !((ExpressionTrait) expr).foldable());
+ }
+
/**
* Identify the expression itself is deterministic or not, default true
*/
@@ -85,7 +92,7 @@ public interface ExpressionTrait extends TreeNode<Expression>
{
}
/**
- * Identify the expression is containing deterministic expr or not
+ * Identify the expression is containing non-deterministic expr or not
*/
default boolean containsNondeterministic() {
return anyMatch(expr -> !((ExpressionTrait) expr).isDeterministic());
diff --git
a/fe/fe-core/src/test/java/org/apache/doris/nereids/rules/expression/rules/SimplifySelfComparisonTest.java
b/fe/fe-core/src/test/java/org/apache/doris/nereids/rules/expression/rules/SimplifySelfComparisonTest.java
index be59404b467..28a5ed3b7c3 100644
---
a/fe/fe-core/src/test/java/org/apache/doris/nereids/rules/expression/rules/SimplifySelfComparisonTest.java
+++
b/fe/fe-core/src/test/java/org/apache/doris/nereids/rules/expression/rules/SimplifySelfComparisonTest.java
@@ -32,12 +32,20 @@ class SimplifySelfComparisonTest extends
ExpressionRewriteTestHelper {
ExpressionRewrite.bottomUp(SimplifySelfComparison.INSTANCE)
));
+ // foldable, cast
assertRewriteAfterTypeCoercion("TA + TB = TA + TB", "NOT ((TA + TB) IS
NULL) OR NULL");
assertRewriteAfterTypeCoercion("TA + TB >= TA + TB", "NOT ((TA + TB)
IS NULL) OR NULL");
assertRewriteAfterTypeCoercion("TA + TB <= TA + TB", "NOT ((TA + TB)
IS NULL) OR NULL");
assertRewriteAfterTypeCoercion("TA + TB <=> TA + TB", "TRUE");
assertRewriteAfterTypeCoercion("TA + TB > TA + TB", "(TA + TB) IS NULL
AND NULL");
assertRewriteAfterTypeCoercion("TA + TB < TA + TB", "(TA + TB) IS NULL
AND NULL");
+ assertRewriteAfterTypeCoercion("DAYS_ADD(CA, 7) <=> DAYS_ADD(CA, 7)",
"TRUE");
+ assertRewriteAfterTypeCoercion("USER() = USER()", "TRUE");
+ assertRewriteAfterTypeCoercion("CURRENT_TIMESTAMP() =
CURRENT_TIMESTAMP()", "TRUE");
+
+ // not foldable, not cast
+ assertRewriteAfterTypeCoercion("random(5, 10) = random(5, 10)",
"random(5, 10) = random(5, 10)");
+ assertRewriteAfterTypeCoercion("random(5, 10) + 100 = random(5, 10) +
100", "random(5, 10) + 100 = random(5, 10) + 100");
}
}
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