From 45c34553db93a4c4bbe1ad6b9051ac342cb57920 Mon Sep 17 00:00:00 2001
From: Alexey Antipovsky <alexey.vladimirovich@mariadb.com>
Date: Wed, 16 Dec 2020 18:50:21 +0300
Subject: [PATCH] MCOL-4453 Fix `SELECT ... LIMIT 0`, now it returns an empty
 set as expected

---
 dbcon/joblist/tupleannexstep.cpp | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/dbcon/joblist/tupleannexstep.cpp b/dbcon/joblist/tupleannexstep.cpp
index 37994ff00..6861681a5 100644
--- a/dbcon/joblist/tupleannexstep.cpp
+++ b/dbcon/joblist/tupleannexstep.cpp
@@ -429,6 +429,13 @@ void TupleAnnexStep::executeNoOrderBy()
                     continue;
                 }
 
+                if (UNLIKELY(fRowsReturned >= fLimitCount))
+                {
+                    fLimitHit = true;
+                    fJobList->abortOnLimit((JobStep*) this);
+                    continue;
+                }
+
                 if (fConstant)
                     fConstant->fillInConstants(fRowIn, fRowOut);
                 else
@@ -441,11 +448,6 @@ void TupleAnnexStep::executeNoOrderBy()
                     fRowOut.nextRow();
                     fRowIn.nextRow();
                 }
-                else
-                {
-                    fLimitHit = true;
-                    fJobList->abortOnLimit((JobStep*) this);
-                }
             }
 
             if (fRowGroupOut.getRowCount() > 0)
@@ -523,15 +525,17 @@ void TupleAnnexStep::executeNoOrderByWithDistinct()
 
                 if (inserted.second)
                 {
-                    fRowGroupOut.incRowCount();
-                    fRowOut.nextRow();
-
-                    if (UNLIKELY(++fRowsReturned >= fLimitCount))
+                    if (UNLIKELY(fRowsReturned >= fLimitCount))
                     {
                         fLimitHit = true;
                         fJobList->abortOnLimit((JobStep*) this);
+                        continue;
                     }
 
+                    ++fRowsReturned;
+                    fRowGroupOut.incRowCount();
+                    fRowOut.nextRow();
+
                     if (UNLIKELY(fRowGroupOut.getRowCount() >= rowgroup::rgCommonSize))
                     {
                         dataVec.push_back(rgDataOut);