From ab1a3fe4719b28928297f8f72322a138cf462ccf Mon Sep 17 00:00:00 2001
From: Serguey Zefirov <serguey.zefirov@mariadb.com>
Date: Thu, 23 Nov 2023 15:49:00 +0300
Subject: [PATCH] Same columns fom diffeernt views in GROUP BY do not produce
 errors

Fixes MCOL-5643.

The problem was that different views with same column names in GROUP BY
and on the SELECT clause produced an error about "projection column is
not an aggergate neither in GROUP BY list."

This was due to incorrect search in expressions's list that lead to
duplicate columns in GROUP BY list.
---
 dbcon/mysql/ha_mcs_execplan.cpp               | 22 ++++++++----
 ...OL-5643-views-group-by-same-columns.result | 26 ++++++++++++++
 ...MCOL-5643-views-group-by-same-columns.test | 36 +++++++++++++++++++
 3 files changed, 77 insertions(+), 7 deletions(-)
 create mode 100644 mysql-test/columnstore/basic/r/MCOL-5643-views-group-by-same-columns.result
 create mode 100644 mysql-test/columnstore/basic/t/MCOL-5643-views-group-by-same-columns.test

diff --git a/dbcon/mysql/ha_mcs_execplan.cpp b/dbcon/mysql/ha_mcs_execplan.cpp
index d2d5bebe8..e72a0fb25 100644
--- a/dbcon/mysql/ha_mcs_execplan.cpp
+++ b/dbcon/mysql/ha_mcs_execplan.cpp
@@ -8173,23 +8173,31 @@ int getSelectPlan(gp_walk_info& gwi, SELECT_LEX& select_lex, SCSEP& csep, bool i
         ReturnedColumn* rc = buildSimpleColumn(ifp, gwi);
         SimpleColumn* sc = dynamic_cast<SimpleColumn*>(rc);
 
-        for (uint32_t j = 0; j < gwi.returnedCols.size(); j++)
-        {
-          if (sc)
+	if (sc)
+	{
+	  bool found = false;
+          for (uint32_t j = 0; j < gwi.returnedCols.size(); j++)
           {
             if (sc->sameColumn(gwi.returnedCols[j].get()))
             {
               sc->orderPos(j);
+	      found = true;
               break;
             }
-            else if (strcasecmp(sc->alias().c_str(), gwi.returnedCols[j]->alias().c_str()) == 0)
+	  }
+          for (uint32_t j = 0; !found && j < gwi.returnedCols.size(); j++)
+          {
+            if (strcasecmp(sc->alias().c_str(), gwi.returnedCols[j]->alias().c_str()) == 0)
             {
               rc = gwi.returnedCols[j].get()->clone();
               rc->orderPos(j);
               break;
             }
           }
-          else
+	}
+	else
+	{
+          for (uint32_t j = 0; j < gwi.returnedCols.size(); j++)
           {
             if (ifp->name.length && string(ifp->name.str) == gwi.returnedCols[j].get()->alias())
             {
@@ -8198,7 +8206,7 @@ int getSelectPlan(gp_walk_info& gwi, SELECT_LEX& select_lex, SCSEP& csep, bool i
               break;
             }
           }
-        }
+	}
 
         if (!rc)
         {
@@ -9920,7 +9928,7 @@ int getGroupPlan(gp_walk_info& gwi, SELECT_LEX& select_lex, SCSEP& csep, cal_gro
             }
           }
 
-          srcp->orderPos(groupcol->counter - 1);
+	  srcp->orderPos(groupcol->counter - 1);
           gwi.groupByCols.push_back(srcp);
           continue;
         }
diff --git a/mysql-test/columnstore/basic/r/MCOL-5643-views-group-by-same-columns.result b/mysql-test/columnstore/basic/r/MCOL-5643-views-group-by-same-columns.result
new file mode 100644
index 000000000..98b65ac33
--- /dev/null
+++ b/mysql-test/columnstore/basic/r/MCOL-5643-views-group-by-same-columns.result
@@ -0,0 +1,26 @@
+drop database if exists MCOL_5643;
+create database MCOL_5643;
+use MCOL_5643;
+create table t1
+(
+id int,
+someStr varchar(100)
+) ENGINE=Columnstore;
+create table t2
+(
+id int,
+fk_t1 int,
+someStr varchar(100)
+) ENGINE=Columnstore;
+insert into t1 values (1, 'bla');
+insert into t2 values (1, 1, 'xyz');
+create view view_on_t1 as select id, someStr from t1;
+create view view_on_t2 as select id, fk_t1, someStr from t2;
+select max(view_on_t1.id), view_on_t1.someStr, view_on_t2.someStr
+from view_on_t1
+left outer join view_on_t2
+on view_on_t1.id = view_on_t2.fk_t1
+group by view_on_t1.someStr, view_on_t2.someStr;
+max(view_on_t1.id)	someStr	someStr
+1	bla	xyz
+drop database MCOL_5643;
diff --git a/mysql-test/columnstore/basic/t/MCOL-5643-views-group-by-same-columns.test b/mysql-test/columnstore/basic/t/MCOL-5643-views-group-by-same-columns.test
new file mode 100644
index 000000000..88610fbab
--- /dev/null
+++ b/mysql-test/columnstore/basic/t/MCOL-5643-views-group-by-same-columns.test
@@ -0,0 +1,36 @@
+--disable_warnings
+drop database if exists MCOL_5643;
+--enable_warnings
+create database MCOL_5643;
+
+use MCOL_5643;
+
+create table t1
+(
+        id int,
+        someStr varchar(100)
+) ENGINE=Columnstore;
+
+create table t2
+(
+        id int,
+        fk_t1 int,
+        someStr varchar(100)
+) ENGINE=Columnstore;
+
+insert into t1 values (1, 'bla');
+insert into t2 values (1, 1, 'xyz');
+
+create view view_on_t1 as select id, someStr from t1;
+create view view_on_t2 as select id, fk_t1, someStr from t2;
+
+# ERROR !!!
+select max(view_on_t1.id), view_on_t1.someStr, view_on_t2.someStr
+from view_on_t1
+left outer join view_on_t2
+on view_on_t1.id = view_on_t2.fk_t1
+group by view_on_t1.someStr, view_on_t2.someStr;
+# ==> All non-aggregate columns in the SELECT and ORDER BY clause must be included in the GROUP BY clause. 0.063 sec
+
+drop database MCOL_5643;
+