From 07561c43d7563f9f197d8973c8486d6425c9bfe6 Mon Sep 17 00:00:00 2001
From: Roman Nozdrin <roman.nozdrin@mariadb.com>
Date: Thu, 30 Aug 2018 17:03:14 +0300
Subject: [PATCH] MCOL-1052 LIMIT processing refactoring in getGroupPlan().

---
 dbcon/execplan/calpontselectexecutionplan.h | 12 ++++++++++++
 dbcon/joblist/joblistfactory.cpp            |  5 +++--
 dbcon/mysql/ha_calpont_execplan.cpp         | 19 +++++++++++--------
 3 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/dbcon/execplan/calpontselectexecutionplan.h b/dbcon/execplan/calpontselectexecutionplan.h
index b3c6458f4..5d1f2fbb6 100644
--- a/dbcon/execplan/calpontselectexecutionplan.h
+++ b/dbcon/execplan/calpontselectexecutionplan.h
@@ -575,6 +575,15 @@ public:
         return fHasOrderBy;
     }
 
+    void specHandlerProcessed(const bool hand)
+    {
+        fSpecHandlerProcessed = hand;
+    }
+    const bool specHandlerProcessed() const
+    {
+        return fSpecHandlerProcessed;
+    } 
+
     void selectSubList(const SelectList& selectSubList)
     {
         fSelectSubList = selectSubList;
@@ -871,6 +880,9 @@ private:
 
     uint32_t fPriority;
     uint32_t fStringTableThreshold;
+    
+    // for specific handlers processing, e.g. GROUP BY
+    bool fSpecHandlerProcessed;
 
     // Derived table involved in the query. For derived table optimization
     std::vector<SCSEP> fSubSelectList;
diff --git a/dbcon/joblist/joblistfactory.cpp b/dbcon/joblist/joblistfactory.cpp
index 8c0615d83..04989e7b7 100644
--- a/dbcon/joblist/joblistfactory.cpp
+++ b/dbcon/joblist/joblistfactory.cpp
@@ -1846,12 +1846,13 @@ void makeVtableModeSteps(CalpontSelectExecutionPlan* csep, JobInfo& jobInfo,
     if (csep->limitNum() != (uint64_t) - 1)
     {
         // special case for outer query order by limit -- return all
-        if (jobInfo.subId == 0 && csep->hasOrderBy())
+        if (jobInfo.subId == 0 && csep->hasOrderBy() && !csep->specHandlerProcessed())
         {
             jobInfo.limitCount = (uint64_t) - 1;
         }
 
-        // support order by and limit in sub-query/union
+        // support order by and limit in sub-query/union or 
+        // GROUP BY handler processed outer query order
         else if (csep->orderByCols().size() > 0)
         {
             addOrderByAndLimit(csep, jobInfo);
diff --git a/dbcon/mysql/ha_calpont_execplan.cpp b/dbcon/mysql/ha_calpont_execplan.cpp
index da0fdbced..0af74c433 100644
--- a/dbcon/mysql/ha_calpont_execplan.cpp
+++ b/dbcon/mysql/ha_calpont_execplan.cpp
@@ -10164,25 +10164,28 @@ int getGroupPlan(gp_walk_info& gwi, SELECT_LEX& select_lex, SCSEP& csep, cal_gro
                 }
             }
 
-            if (ord_cols.length() > 0)	// has order by
+            if ( gwi.orderByCols.size() )	// has order by
             {
                 gwi.thd->infinidb_vtable.has_order_by = true;
                 csep->hasOrderBy(true);
-                ord_cols = " order by " + ord_cols;
-                select_query += ord_cols;
+                csep->specHandlerProcessed(true);
             }
         }
 
         // LIMIT and OFFSET are extracted from TABLE_LIST elements.
         // All of JOIN-ed tables contain relevant limit and offset.
-        if (gi.groupByTables->select_lex->select_limit)
+        uint64_t limit = (uint64_t)-1;
+        if (gi.groupByTables->select_lex->select_limit && 
+            ( limit = static_cast<Item_int*>(gi.groupByTables->select_lex->select_limit)->val_int() ) &&
+            limit != (uint64_t)-1 )
         {
-            csep->limitNum(((Item_int*)gi.groupByTables->select_lex->select_limit)->val_int());
+            csep->limitNum(limit);
         }
-        else
+        else if (csep->hasOrderBy()) 
         {
-            if (csep->hasOrderBy())
-                csep->limitNum((uint64_t) - 2);
+            // We use LimitedOrderBy so set the limit to
+            // go through the check in addOrderByAndLimit
+            csep->limitNum((uint64_t) - 2);
         }
 
         if (gi.groupByTables->select_lex->offset_limit)