From 0c1458f21f6142a707b59f3923aba4f0b578bf93 Mon Sep 17 00:00:00 2001
From: starocean999 <40539150+starocean999@users.noreply.github.com>
Date: Wed, 8 Nov 2023 20:46:29 +0800
Subject: [PATCH] [fix](planner)isnull predicate can't be safely constant
 folded in inlineview (#25377)
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disable is null predicate constant fold rule for inline view
consider sql
select c.*
from (
select a.*, b.x
from test_insert a left join
(select 'some_const_str' x from test_insert) b on true
) c
where c.x is null;

when push “c.x is null” into c, after folding constant rule, it will get empty result. Because x is 'some_const_str' and "x is null" will be evaluated to false. This is wrong.
---
 .../java/org/apache/doris/analysis/IsNullPredicate.java     | 2 +-
 .../java/org/apache/doris/rewrite/FoldConstantsRule.java    | 6 +++++-
 .../suites/query_p0/literal_view/lietral_test.groovy        | 6 ++++++
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/fe/fe-core/src/main/java/org/apache/doris/analysis/IsNullPredicate.java b/fe/fe-core/src/main/java/org/apache/doris/analysis/IsNullPredicate.java
index bf81cb4810..c67ca1b060 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/analysis/IsNullPredicate.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/analysis/IsNullPredicate.java
@@ -160,7 +160,7 @@ public class IsNullPredicate extends Predicate {
         // after outer join
         recursiveResetChildrenResult(!forPushDownPredicatesToView);
         final Expr childValue = getChild(0);
-        if (!(childValue instanceof LiteralExpr)) {
+        if (forPushDownPredicatesToView || !(childValue instanceof LiteralExpr)) {
             return this;
         }
         return childValue instanceof NullLiteral ? new BoolLiteral(!isNotNull) : new BoolLiteral(isNotNull);
diff --git a/fe/fe-core/src/main/java/org/apache/doris/rewrite/FoldConstantsRule.java b/fe/fe-core/src/main/java/org/apache/doris/rewrite/FoldConstantsRule.java
index 509e78ffb8..e28feabbf4 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/rewrite/FoldConstantsRule.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/rewrite/FoldConstantsRule.java
@@ -29,6 +29,7 @@ import org.apache.doris.analysis.Expr;
 import org.apache.doris.analysis.InformationFunction;
 import org.apache.doris.analysis.LiteralExpr;
 import org.apache.doris.analysis.NullLiteral;
+import org.apache.doris.analysis.SlotRef;
 import org.apache.doris.analysis.VariableExpr;
 import org.apache.doris.catalog.Env;
 import org.apache.doris.catalog.PrimitiveType;
@@ -124,7 +125,10 @@ public class FoldConstantsRule implements ExprRewriteRule {
                 return expr;
             }
         }
-        return expr.getResultValue(false);
+        // it may be wrong to fold constant value in inline view
+        // so pass the info to getResultValue method to let predicate itself
+        // to decide if it can fold constant value safely
+        return expr.getResultValue(expr instanceof SlotRef ? false : analyzer.isInlineViewAnalyzer());
     }
 
     /**
diff --git a/regression-test/suites/query_p0/literal_view/lietral_test.groovy b/regression-test/suites/query_p0/literal_view/lietral_test.groovy
index 905ed6696d..b19f33e293 100644
--- a/regression-test/suites/query_p0/literal_view/lietral_test.groovy
+++ b/regression-test/suites/query_p0/literal_view/lietral_test.groovy
@@ -140,4 +140,10 @@ suite("literal_view_test") {
         sql "select * from (select null as top) t where top = 5"
         result ([])
     }
+
+    sql """set enable_nereids_planner=false;"""
+    explain {
+        sql """ select c.* from ( select a.*, '' x from test_insert a left join test_insert b on true ) c where c.x is null; """
+        notContains("VEMPTYSET")
+    }
 }