fix(query): fix diff function result type to avoid overflow

TD-16068

source/libs/function/src/builtins.c

@@ -709,7 +709,13 @@ static int32_t translateDiff(SFunctionNode* pFunc, char* pErrBuf, int32_t len) {
     pValue->notReserved = true;
   }
 
-  pFunc->node.resType = (SDataType){.bytes = tDataTypes[colType].bytes, .type = colType};
+  uint8_t resType;
+  if (IS_SIGNED_NUMERIC_TYPE(colType)) {
+    resType = TSDB_DATA_TYPE_BIGINT;
+  } else {
+    resType = TSDB_DATA_TYPE_DOUBLE;
+  }
+  pFunc->node.resType = (SDataType){.bytes = tDataTypes[resType].bytes, .type = resType};
   return TSDB_CODE_SUCCESS;
 }
 

source/libs/function/src/builtinsimpl.c

@@ -2299,15 +2299,15 @@ static void doSetPrevVal(SDiffInfo* pDiffInfo, int32_t type, const char* pv) {
 }
 
 static void doHandleDiff(SDiffInfo* pDiffInfo, int32_t type, const char* pv, SColumnInfoData* pOutput, int32_t pos, int32_t order) {
-    int32_t factor = (order == TSDB_ORDER_ASC)? 1:-1;
+  int32_t factor = (order == TSDB_ORDER_ASC)? 1:-1;
   switch (type) {
     case TSDB_DATA_TYPE_INT: {
       int32_t v = *(int32_t*)pv;
-      int32_t delta = factor*(v - pDiffInfo->prev.i64);  // direct previous may be null
+      int64_t delta = factor*(v - pDiffInfo->prev.i64);  // direct previous may be null
       if (delta < 0 && pDiffInfo->ignoreNegative) {
         colDataSetNull_f(pOutput->nullbitmap, pos);
       } else {
-        colDataAppendInt32(pOutput, pos, &delta);
+        colDataAppendInt64(pOutput, pos, &delta);
       }
       pDiffInfo->prev.i64 = v;
       break;
@@ -2315,22 +2315,22 @@ static void doHandleDiff(SDiffInfo* pDiffInfo, int32_t type, const char* pv, SCo
     case TSDB_DATA_TYPE_BOOL:
     case TSDB_DATA_TYPE_TINYINT: {
       int8_t v = *(int8_t*)pv;
-      int8_t delta = factor*(v - pDiffInfo->prev.i64);  // direct previous may be null
+      int64_t delta = factor*(v - pDiffInfo->prev.i64);  // direct previous may be null
       if (delta < 0 && pDiffInfo->ignoreNegative) {
         colDataSetNull_f(pOutput->nullbitmap, pos);
       } else {
-        colDataAppendInt8(pOutput, pos, &delta);
+        colDataAppendInt64(pOutput, pos, &delta);
       }
       pDiffInfo->prev.i64 = v;
       break;
     }
     case TSDB_DATA_TYPE_SMALLINT: {
       int16_t v = *(int16_t*)pv;
-      int16_t delta = factor*(v - pDiffInfo->prev.i64);  // direct previous may be null
+      int64_t delta = factor*(v - pDiffInfo->prev.i64);  // direct previous may be null
       if (delta < 0 && pDiffInfo->ignoreNegative) {
         colDataSetNull_f(pOutput->nullbitmap, pos);
       } else {
-        colDataAppendInt16(pOutput, pos, &delta);
+        colDataAppendInt64(pOutput, pos, &delta);
       }
       pDiffInfo->prev.i64 = v;
       break;
@@ -2348,11 +2348,11 @@ static void doHandleDiff(SDiffInfo* pDiffInfo, int32_t type, const char* pv, SCo
     }
     case TSDB_DATA_TYPE_FLOAT: {
       float v = *(float*)pv;
-      float delta = factor*(v - pDiffInfo->prev.d64);  // direct previous may be null
+      double delta = factor*(v - pDiffInfo->prev.d64);  // direct previous may be null
       if ((delta < 0 && pDiffInfo->ignoreNegative) || isinf(delta) || isnan(delta)) { //check for overflow
         colDataSetNull_f(pOutput->nullbitmap, pos);
       } else {
-        colDataAppendFloat(pOutput, pos, &delta);
+        colDataAppendDouble(pOutput, pos, &delta);
       }
       pDiffInfo->prev.d64 = v;
       break;