From 80d2e6f4c1815017e467ceb61344be9d3e581350 Mon Sep 17 00:00:00 2001
From: minghong <englefly@gmail.com>
Date: Fri, 24 Mar 2023 21:37:06 +0800
Subject: [PATCH] [fix](nereids) should not assign stats after cast on the
 original slot (#18061)

select * from T where A = 10.0
suppose A is int column
after stats derive on `cast(A as double) = 10.0`,

we set column stats for `cast(A as double)` on `A`
---
 .../doris/nereids/stats/FilterEstimation.java | 24 ++++++-------------
 1 file changed, 7 insertions(+), 17 deletions(-)

diff --git a/fe/fe-core/src/main/java/org/apache/doris/nereids/stats/FilterEstimation.java b/fe/fe-core/src/main/java/org/apache/doris/nereids/stats/FilterEstimation.java
index e58f06105e..f2904d38af 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/nereids/stats/FilterEstimation.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/nereids/stats/FilterEstimation.java
@@ -20,6 +20,7 @@ package org.apache.doris.nereids.stats;
 import org.apache.doris.nereids.stats.FilterEstimation.EstimationContext;
 import org.apache.doris.nereids.trees.TreeNode;
 import org.apache.doris.nereids.trees.expressions.And;
+import org.apache.doris.nereids.trees.expressions.Cast;
 import org.apache.doris.nereids.trees.expressions.ComparisonPredicate;
 import org.apache.doris.nereids.trees.expressions.CompoundPredicate;
 import org.apache.doris.nereids.trees.expressions.EqualTo;
@@ -210,25 +211,14 @@ public class FilterEstimation extends ExpressionVisitor<Statistics, EstimationCo
             if (statsForLeft.histogram != null) {
                 return estimateEqualToWithHistogram(cp.left(), statsForLeft, val, context);
             }
-            // cp.left : func(A), we assume func(A) has same statistics with A
-            // for example: cast(N_NAME as varchar(*)) = 'GERMANY',
-            // we assume cast(N_NAME as varchar(*)) and N_NAME have the same col stats
-            Set<Slot> leftSlots = cp.left().getInputSlots();
-            Preconditions.checkArgument(leftSlots.size() <= 1,
-                    "stats derive: equal condition only support at one column, but we meet "
-                            + leftSlots.size()
-            );
 
             Statistics equalStats = context.statistics.withSel(selectivity);
-            /*
-            leftSlots could be empty, for example:
-            select * from (select 'jj' as kk1, sum(k2) from ${tableName2} where k10 = '2015-04-02' group by kk1)tt
-            where kk1 in ('jj')
-            kk1 in ('jj') => kk1 = 'jj' => 'jj'='jj
-            TODO const fold could eliminate this equalTo.
-             */
-            if (!leftSlots.isEmpty()) {
-                Slot leftSlot = leftSlots.iterator().next();
+            Expression left = cp.left();
+            if (left instanceof Cast) {
+                left = ((Cast) left).child();
+            }
+            if (left instanceof SlotReference) {
+                Slot leftSlot = (SlotReference) left;
                 //update min/max of cp.left
                 ColumnStatistic columnStats = equalStats.findColumnStatistics(leftSlot);
                 ColumnStatisticBuilder colStatsBuilder = new ColumnStatisticBuilder(columnStats);