[TD-10986]<feature>: Add elapsed function.

src/client/src/tscUtil.c

@@ -380,7 +380,7 @@ bool tscIsPointInterpQuery(SQueryInfo* pQueryInfo) {
 }
 
 bool tscNeedTableSeqScan(SQueryInfo* pQueryInfo) {
-  return tscQueryContainsFunction(pQueryInfo, TSDB_FUNC_TWA) || tscQueryContainsFunction(pQueryInfo, TSDB_FUNC_ELAPSED);
+  return pQueryInfo->stableQuery && (tscQueryContainsFunction(pQueryInfo, TSDB_FUNC_TWA) || tscQueryContainsFunction(pQueryInfo, TSDB_FUNC_ELAPSED));
 }
 
 bool tsIsArithmeticQueryOnAggResult(SQueryInfo* pQueryInfo) {

src/query/src/qAggMain.c

@@ -5090,23 +5090,54 @@ static void elapsedFunction(SQLFunctionCtx *pCtx) {
       pInfo->min = pCtx->preAggVals.statis.min;
       pInfo->max = pCtx->preAggVals.statis.max;
     } else {
-      pInfo->max = pCtx->preAggVals.statis.max;
+      if (pCtx->order == TSDB_ORDER_ASC) {
+        pInfo->max = pCtx->preAggVals.statis.max;
+      } else {
+        pInfo->min = pCtx->preAggVals.statis.min;
+      }
     }
   } else {
+    // 0 == pCtx->size mean this is end interpolation.
     if (0 == pCtx->size) {
+      if (pCtx->order == TSDB_ORDER_DESC) {
+        if (pCtx->end.key != INT64_MIN) {
+          pInfo->min = pCtx->end.key;
+        }
+      } else {
+        if (pCtx->end.key != INT64_MIN) {
+          pInfo->max = pCtx->end.key + 1;
+        }
+      }
       goto elapsedOver;
     }
 
-    if (pCtx->start.key == INT64_MIN) {
-      pInfo->min = pCtx->ptsList[0];
-    } else {
-      pInfo->min = pCtx->start.key;
-    }
+    int64_t *ptsList = (int64_t *)GET_INPUT_DATA_LIST(pCtx);
+    // pCtx->start.key == INT64_MIN mean this is first window or there is actual start point of current window.
+    // pCtx->end.key == INT64_MIN mean current window does not end in current data block or there is actual end point of current window.
+    if (pCtx->order == TSDB_ORDER_DESC) {
+      if (pCtx->start.key == INT64_MIN) {
+        pInfo->max = (pInfo->max < ptsList[pCtx->size - 1]) ? ptsList[pCtx->size - 1] : pInfo->max;
+      } else {
+        pInfo->max = pCtx->start.key + 1;
+      }
 
-    if (pCtx->end.key != INT64_MIN) {
-      pInfo->max = pCtx->end.key + 1;
+      if (pCtx->end.key != INT64_MIN) {
+        pInfo->min = pCtx->end.key;
+      } else {
+        pInfo->min = ptsList[0];
+      }
     } else {
-      pInfo->max = pCtx->ptsList[pCtx->size - 1];
+      if (pCtx->start.key == INT64_MIN) {
+        pInfo->min = (pInfo->min > ptsList[0]) ? ptsList[0] : pInfo->min;
+      } else {
+        pInfo->min = pCtx->start.key;
+      }
+
+      if (pCtx->end.key != INT64_MIN) {
+        pInfo->max = pCtx->end.key + 1;
+      } else {
+        pInfo->max = ptsList[pCtx->size - 1];
+      }
     }
   }
 

src/query/src/qExecutor.c

@@ -1531,7 +1531,6 @@ static void hashIntervalAgg(SOperatorInfo* pOperatorInfo, SResultRowInfo* pResul
 
   STimeWindow win = getActiveTimeWindow(pResultRowInfo, ts, pQueryAttr);
   bool masterScan = IS_MASTER_SCAN(pRuntimeEnv);
-
   SResultRow* pResult = NULL;
   int32_t ret = setResultOutputBufByKey(pRuntimeEnv, pResultRowInfo, pSDataBlock->info.tid, &win, masterScan, &pResult, tableGroupId, pInfo->pCtx,
                                         numOfOutput, pInfo->rowCellInfoOffset);
@@ -1554,23 +1553,22 @@ static void hashIntervalAgg(SOperatorInfo* pOperatorInfo, SResultRowInfo* pResul
         continue;
       }
 
-        STimeWindow w = pRes->win;
-        ret = setResultOutputBufByKey(pRuntimeEnv, pResultRowInfo, pSDataBlock->info.tid, &w, masterScan, &pResult,
-                                      tableGroupId, pInfo->pCtx, numOfOutput, pInfo->rowCellInfoOffset);
-        if (ret != TSDB_CODE_SUCCESS) {
-          longjmp(pRuntimeEnv->env, TSDB_CODE_QRY_OUT_OF_MEMORY);
-        }
-
-        assert(!resultRowInterpolated(pResult, RESULT_ROW_END_INTERP));
+      STimeWindow w = pRes->win;
+      ret = setResultOutputBufByKey(pRuntimeEnv, pResultRowInfo, pSDataBlock->info.tid, &w, masterScan, &pResult,
+                                    tableGroupId, pInfo->pCtx, numOfOutput, pInfo->rowCellInfoOffset);
+      if (ret != TSDB_CODE_SUCCESS) {
+        longjmp(pRuntimeEnv->env, TSDB_CODE_QRY_OUT_OF_MEMORY);
+      }
 
-        doTimeWindowInterpolation(pOperatorInfo, pInfo, pSDataBlock->pDataBlock, *(TSKEY*)pRuntimeEnv->prevRow[0], -1,
-                                  tsCols[startPos], startPos, w.ekey, RESULT_ROW_END_INTERP);
+      assert(!resultRowInterpolated(pResult, RESULT_ROW_END_INTERP));
 
-        setResultRowInterpo(pResult, RESULT_ROW_END_INTERP);
-        setNotInterpoWindowKey(pInfo->pCtx, pQueryAttr->numOfOutput, RESULT_ROW_START_INTERP);
+      doTimeWindowInterpolation(pOperatorInfo, pInfo, pSDataBlock->pDataBlock, *(TSKEY*)pRuntimeEnv->prevRow[0], -1,
+                                tsCols[startPos], startPos, QUERY_IS_ASC_QUERY(pQueryAttr) ? w.ekey : w.skey, RESULT_ROW_END_INTERP);
 
-        doApplyFunctions(pRuntimeEnv, pInfo->pCtx, &w, startPos, 0, tsCols, pSDataBlock->info.rows, numOfOutput);
-      }
+      setResultRowInterpo(pResult, RESULT_ROW_END_INTERP);
+      setNotInterpoWindowKey(pInfo->pCtx, pQueryAttr->numOfOutput, RESULT_ROW_START_INTERP);
+      doApplyFunctions(pRuntimeEnv, pInfo->pCtx, &w, startPos, 0, tsCols, pSDataBlock->info.rows, numOfOutput);
+    }
 
     // restore current time window
     ret = setResultOutputBufByKey(pRuntimeEnv, pResultRowInfo, pSDataBlock->info.tid, &win, masterScan, &pResult, tableGroupId, pInfo->pCtx,