From b64c30cfdb4cec823510c3067f35904534fce087 Mon Sep 17 00:00:00 2001
From: Haojun Liao <hjliao@taosdata.com>
Date: Tue, 29 Dec 2020 18:57:52 +0800
Subject: [PATCH] [TD-2610]<fix>: fix twa bug in case of all data is NULL.

---
 src/client/src/tscFunctionImpl.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/client/src/tscFunctionImpl.c b/src/client/src/tscFunctionImpl.c
index 22240efe14..5a30d733fa 100644
--- a/src/client/src/tscFunctionImpl.c
+++ b/src/client/src/tscFunctionImpl.c
@@ -3810,11 +3810,15 @@ static void twa_function(SQLFunctionCtx *pCtx) {
   // skip null value
   int32_t step = GET_FORWARD_DIRECTION_FACTOR(pCtx->order);
   int32_t i = (pCtx->order == TSDB_ORDER_ASC)? 0:(pCtx->size - 1);
-  while (pCtx->hasNull && i < pCtx->size && isNull((char *)data + pCtx->inputBytes * i, pCtx->inputType)) {
+  while (pCtx->hasNull && i < pCtx->size && i >= 0 && isNull((char *)data + pCtx->inputBytes * i, pCtx->inputType)) {
     i += step;
   }
 
-  int32_t notNullElems = twa_function_impl(pCtx, pCtx->startOffset, i, pCtx->size);
+  int32_t notNullElems = 0;
+  if (i >= 0 && i < pCtx->size) {
+    notNullElems = twa_function_impl(pCtx, pCtx->startOffset, i, pCtx->size);
+  }
+
   SET_VAL(pCtx, notNullElems, 1);
   
   if (notNullElems > 0) {
-- 
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