From e6d1aa27f4a81da1a6725a4209bc09ad334d664b Mon Sep 17 00:00:00 2001
From: Roman Nozdrin <roman.nozdrin@mariadb.com>
Date: Wed, 8 Apr 2020 13:41:30 +0000
Subject: [PATCH] MCOL-3903 10.5 allows engines to process LIMIT and OFFSET on
 their own.

---
 dbcon/mysql/ha_mcs_execplan.cpp | 27 ++-------------------------
 1 file changed, 2 insertions(+), 25 deletions(-)

diff --git a/dbcon/mysql/ha_mcs_execplan.cpp b/dbcon/mysql/ha_mcs_execplan.cpp
index eca370187..d75137728 100755
--- a/dbcon/mysql/ha_mcs_execplan.cpp
+++ b/dbcon/mysql/ha_mcs_execplan.cpp
@@ -6617,7 +6617,6 @@ int processLimitAndOffset(
         if (select_lex.join)
         {
             JOIN* join = select_lex.join;
-#if MYSQL_VERSION_ID >= 50172
 
             // @bug5729. After upgrade, join->unit sometimes is uninitialized pointer
             // (not null though) and will cause seg fault. Prefer checking
@@ -6633,14 +6632,9 @@ int processLimitAndOffset(
             }
             else if (join->unit)
             {
-                limitOffset = join->unit->offset_limit_cnt;
-                limitNum = join->unit->select_limit_cnt - limitOffset;
+                limitOffset = join->unit->lim.get_offset_limit();
+                limitNum = join->unit->lim.get_select_limit() - limitOffset;
             }
-
-#else
-            limitOffset = (join->unit)->offset_limit_cnt;
-            limitNum = (join->unit)->select_limit_cnt - (join->unit)->offset_limit_cnt;
-#endif
         }
         else
         {
@@ -6675,23 +6669,6 @@ int processLimitAndOffset(
         return ER_CHECK_NOT_IMPLEMENTED;
     }
 
-    // MDB applies OFFSET on its own for SH processing.
-    // See related MDEV-16327 for details.
-    if (isSelectHandlerTop && csep->limitStart())
-    {
-        if (std::numeric_limits<uint64_t>::max()-csep->limitStart()
-            < csep->limitNum())
-        {
-            csep->limitNum(std::numeric_limits<uint64_t>::max());
-            csep->limitStart(0);
-        }
-        else
-        {
-            csep->limitNum(csep->limitNum()+csep->limitStart());
-            csep->limitStart(0);
-        }
-    }
-
     return 0;
 }