From ded698127ea862add64c73cc3c2e33ccc7e34be2 Mon Sep 17 00:00:00 2001
From: minghong <englefly@gmail.com>
Date: Mon, 13 Feb 2023 15:27:47 +0800
Subject: [PATCH] [fix](planner) fix bug for missing slot (#16601)

In previous version, if the output slot of analyticExpr is not materialized, the analyticExpr is pruned.
But there are some cases that it cannot be pruned.
For example:

                   SELECT
                        count(*)
                    FROM T1,
                        (SELECT dd
                        FROM (
                            SELECT
                                1.1 as cc,
                                ROW_NUMBER() OVER() as dd
                            FROM T2
                            ) V1
                        ORDER BY cc DESC
                        limit 1
                        ) V2;

 analyticExpr(ROW_NUMBER() OVER() as dd) is not materialized, but we have to generate
 WindowGroup for it.
 tmp.dd is used by upper count(*), we have to generate data for tmp.dd

In this fix, if an inline view only output one column(in this example, the 'dd'), we materialize this column.

TODO:
 In order to prune 'ROW_NUMBER() OVER() as dd', we need to rethink the rule of choosing a column
 for count(*). (refer to SingleNodePlanner.materializeTableResultForCrossJoinOrCountStar)
 V2 can be transformed to

       SELECT cc
        FROM (
            SELECT
                1.1 as cc,
                ROW_NUMBER() OVER() as dd
            FROM T2
            ) V1
        ORDER BY cc DESC
        limit 1
        ) V2;

Except the byte size of cc and dd, we need to consider the cost to generate cc and dd.
---
 .../apache/doris/planner/SingleNodePlanner.java | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/fe/fe-core/src/main/java/org/apache/doris/planner/SingleNodePlanner.java b/fe/fe-core/src/main/java/org/apache/doris/planner/SingleNodePlanner.java
index 1003991f46..2d5bc41d07 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/planner/SingleNodePlanner.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/planner/SingleNodePlanner.java
@@ -1193,6 +1193,23 @@ public class SingleNodePlanner {
             // create left-deep sequence of binary hash joins; assign node ids as we go along
             TableRef tblRef = selectStmt.getTableRefs().get(0);
             materializeTableResultForCrossJoinOrCountStar(tblRef, analyzer);
+            if (selectStmt.getSelectList().getItems().size() == 1) {
+                final List<SlotId> slotIds = Lists.newArrayList();
+                final List<TupleId> tupleIds = Lists.newArrayList();
+                Expr resultExprSelected = selectStmt.getSelectList().getItems().get(0).getExpr();
+                if (resultExprSelected != null && resultExprSelected instanceof SlotRef) {
+                    resultExprSelected.getIds(tupleIds, slotIds);
+                    for (SlotId id : slotIds) {
+                        final SlotDescriptor slot = analyzer.getDescTbl().getSlotDesc(id);
+                        slot.setIsMaterialized(true);
+                        slot.materializeSrcExpr();
+                    }
+                    for (TupleId id : tupleIds) {
+                        final TupleDescriptor tuple = analyzer.getDescTbl().getTupleDesc(id);
+                        tuple.setIsMaterialized(true);
+                    }
+                }
+            }
             root = createTableRefNode(analyzer, tblRef, selectStmt);
             // to change the inner contains analytic function
             // selectStmt.seondSubstituteInlineViewExprs(analyzer.getChangeResSmap());