From d422bba8ddd25dc739ae11ae431bf5900905c4c6 Mon Sep 17 00:00:00 2001
From: Haojun Liao <hjliao@taosdata.com>
Date: Tue, 16 Mar 2021 18:24:51 +0800
Subject: [PATCH] [td-3318]<fix>: fix crash caused by empty stddev query.

---
 src/query/src/qExecutor.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/query/src/qExecutor.c b/src/query/src/qExecutor.c
index 8f3c51d2a9..e0e18a7cc8 100644
--- a/src/query/src/qExecutor.c
+++ b/src/query/src/qExecutor.c
@@ -4170,8 +4170,10 @@ static SSDataBlock* doTableScan(void* param) {
       assert(ret);
     }
 
-    pResultRowInfo->curIndex = 0;
-    pResultRowInfo->prevSKey = pResultRowInfo->pResult[0]->win.skey;
+    if (pResultRowInfo->size > 0) {
+      pResultRowInfo->curIndex = 0;
+      pResultRowInfo->prevSKey = pResultRowInfo->pResult[0]->win.skey;
+    }
 
     qDebug("QInfo:%p start to repeat scan data blocks due to query func required, qrange:%" PRId64 "-%" PRId64,
            pRuntimeEnv->qinfo, cond.twindow.skey, cond.twindow.ekey);
-- 
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