From 6f3023fba950a05f999f09c3babda96c729f02c8 Mon Sep 17 00:00:00 2001
From: Haojun Liao <hjliao@taosdata.com>
Date: Thu, 29 Oct 2020 12:01:57 +0800
Subject: [PATCH] [td-1826]

---
 src/query/src/qExecutor.c                     |   5 +-
 .../script/general/parser/join_multivnode.sim | 127 +++++++++++++++++-
 2 files changed, 130 insertions(+), 2 deletions(-)

diff --git a/src/query/src/qExecutor.c b/src/query/src/qExecutor.c
index 9903a01e2f..3e7c6c46df 100644
--- a/src/query/src/qExecutor.c
+++ b/src/query/src/qExecutor.c
@@ -1854,8 +1854,11 @@ static bool needReverseScan(SQuery *pQuery) {
     }
 
     if (functionId == TSDB_FUNC_LAST || functionId == TSDB_FUNC_LAST_DST) {
+      // the scan order to acquire the last result of the specified column
       int32_t order = (int32_t)pQuery->pSelectExpr[i].base.arg->argValue.i64;
-      return order != pQuery->order.order;
+      if (order != pQuery->order.order) {
+        return true;
+      }
     }
   }
 
diff --git a/tests/script/general/parser/join_multivnode.sim b/tests/script/general/parser/join_multivnode.sim
index a8f8e33dd5..5e4a0990c1 100644
--- a/tests/script/general/parser/join_multivnode.sim
+++ b/tests/script/general/parser/join_multivnode.sim
@@ -132,9 +132,134 @@ sql select join_mt0.ts, join_mt1.t1, join_mt0.t1, join_mt1.tbname, join_mt0.tbna
 
 sql select join_mt0.ts, join_mt1.t1, join_mt0.t1, join_mt1.tbname, join_mt0.tbname from join_mt0, join_mt1 where join_mt0.ts=join_mt1.ts and join_mt0.t1=join_mt1.t1 limit 1
 
-sql select count(join_mt0.c1), sum(join_mt1.c2), first(join_mt0.c5), last(join_mt1.c7) from join_mt0, join_mt1 where join_mt0.t1=join_mt1.t1 and join_mt0.ts=join_mt1.ts interval(10a) group by join_mt0.t1 order by join_mt0.ts desc;
+#1970-01-01 08:01:40.800 |                    10 |              45.000000000 |         0 |     true |     false |           0 |
+#1970-01-01 08:01:40.790 |                    10 |             945.000000000 |        90 |     true |      true |           0 |
+
+sql select count(join_mt0.c1), sum(join_mt1.c2), first(join_mt0.c5), last(join_mt1.c7), first(join_mt1.c7) from join_mt0, join_mt1 where join_mt0.t1=join_mt1.t1 and join_mt0.ts=join_mt1.ts interval(10a) group by join_mt0.t1 order by join_mt0.ts desc limit 20 offset 19;
+if $rows != 100 then
+  return -1
+endi
+
+# c5 is null ! error
+
+sql select count(join_mt0.c1), sum(join_mt0.c2)/count(*), avg(c2), first(join_mt0.c5), last(c7) from join_mt0  interval(10a) group by join_mt0.t1 order by join_mt0.ts desc;
 if $rows != 100 then
   return -1
 endi
 
+if $data00 != @70-01-01 08:01:40.990@ then
+  print expect 0, actual: $data00
+  return -1
+endi
+
+if $data01 != 30 then
+  return -1
+endi
+
+if $data02 != 94.500000000 then
+  print expect 94.500000000, actual $data02
+  return -1
+endi
+
+if $data03 != 94.500000000 then
+  return -1
+endi
+
+if $data04 != 90 then
+  return -1
+endi
+
+if $data05 != 1 then
+  return -1
+endi
+
+if $data06 != 2 then
+  return -1
+endi
+
+if $data10 != @70-01-01 08:01:40.980@ then
+  print expect 70-01-01 08:01:40.980, actual: $data10
+  return -1
+endi
+
+if $data11 != 30 then
+  return -1
+endi
+
+if $data12 != 84.500000000 then
+  print expect 84.500000000, actual $data12
+  return -1
+endi
+
+if $data13 != 84.500000000 then
+  return -1
+endi
+
+if $data14 != 80 then
+  return -1
+endi
+
+if $data15 != 1 then
+  return -1
+endi
+
+if $data16 != 2 then
+  return -1
+endi
+
+# this function will cause shell crash
+sql select count(join_mt0.c1), first(join_mt0.c1) from join_mt0, join_mt1 where join_mt0.t1=join_mt1.t1 and join_mt0.ts=join_mt1.ts interval(10a) group by join_mt0.t1 order by join_mt0.ts desc;
+if $rows != 100 then
+  return -1
+endi
+
+if $data00 != @70-01-01 08:01:40.990@ then
+  return -1
+endi
+
+if $data01 != 10 then
+  return -1
+endi
+
+if $data02 != 90 then
+  return -1
+endi
+
+if $data03 != 0 then
+  return -1
+endi
+
+if $data11 != 10 then
+  return -1
+endi
+
+if $data12 != 80 then
+  return -1
+endi
+
+if $data13 != 0 then
+  return -1
+endi
+
+sql select last(join_mt1.c7), first(join_mt1.c7) from join_mt0, join_mt1 where join_mt0.t1=join_mt1.t1 and join_mt0.ts=join_mt1.ts interval(10m) group by join_mt0.t1 order by join_mt0.ts asc;
+if $rows != 1 then
+ return -1
+endi
+
+if $data00 != @70-01-01 08:00:00.000@ then
+  return -1
+endi
+
+if $data01 != 1 then
+  return -1
+endi
+
+if $data02 != 0 then
+  return -1
+endi
+
+if $data03 != 0 then
+  return -1
+endi
+
 system sh/exec.sh -n dnode1 -s stop -x SIGINT
\ No newline at end of file
-- 
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