From 5062604688c5ffcb39ece6bf3c093782799096aa Mon Sep 17 00:00:00 2001
From: Haojun Liao <hjliao@taosdata.com>
Date: Thu, 17 Jun 2021 14:24:53 +0800
Subject: [PATCH] [td-4739]<fix>: fix bug in derivative.

---
 src/client/src/tscUtil.c                 |  1 +
 src/query/src/qAggMain.c                 | 11 +----------
 tests/script/general/parser/function.sim |  6 ++++++
 3 files changed, 8 insertions(+), 10 deletions(-)

diff --git a/src/client/src/tscUtil.c b/src/client/src/tscUtil.c
index 9011bae47b..89f2563e14 100644
--- a/src/client/src/tscUtil.c
+++ b/src/client/src/tscUtil.c
@@ -3477,6 +3477,7 @@ static void tscSubqueryRetrieveCallback(void* param, TAOS_RES* tres, int code) {
   if (pSql->res.code == TSDB_CODE_SUCCESS) {
     (*pSql->fp)(pParentSql->param, pParentSql, pParentSql->res.numOfRows);
   } else {
+    pParentSql->res.code = pSql->res.code;
     tscAsyncResultOnError(pParentSql);
   }
 }
diff --git a/src/query/src/qAggMain.c b/src/query/src/qAggMain.c
index 68de902556..bc14c75af5 100644
--- a/src/query/src/qAggMain.c
+++ b/src/query/src/qAggMain.c
@@ -3613,16 +3613,7 @@ static void deriv_function(SQLFunctionCtx *pCtx) {
       qError("error input type");
   }
 
-  // initial value is not set yet, all data block are null
-  if (!pDerivInfo->valueSet || notNullElems <= 0) {
-    /*
-     * 1. current block and blocks before are full of null
-     * 2. current block may be null value
-     */
-    assert(pCtx->hasNull);
-  } else {
-    GET_RES_INFO(pCtx)->numOfRes += notNullElems;
-  }
+  GET_RES_INFO(pCtx)->numOfRes += notNullElems;
 }
 
 #define DIFF_IMPL(ctx, d, type)                                                              \
diff --git a/tests/script/general/parser/function.sim b/tests/script/general/parser/function.sim
index ad900b92e0..827f21f0bf 100644
--- a/tests/script/general/parser/function.sim
+++ b/tests/script/general/parser/function.sim
@@ -1073,6 +1073,12 @@ sql insert into t0 values('2020-1-1 1:3:9', 9);
 sql insert into t0 values('2020-1-1 1:4:10', 10);
 
 sql insert into t1 values('2020-1-1 1:1:2', 2);
+print ===========================>td-4739
+sql select diff(val) from (select derivative(k, 1s, 0) from t1);
+if $rows != 0 then
+  return -1
+endi
+
 sql insert into t1 values('2020-1-1 1:1:4', 20);
 sql insert into t1 values('2020-1-1 1:1:6', 200);
 sql insert into t1 values('2020-1-1 1:1:8', 2000);
-- 
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