feat(query): a new builtin aggregate function is added.

source/libs/function/src/builtinsimpl.c

@@ -819,6 +819,8 @@ int32_t firstFunction(SqlFunctionCtx *pCtx) {
         continue;
       }
 
+      numOfElems++;
+
       char* data = colDataGetData(pInputCol, i);
       TSKEY cts = getRowPTs(pInput->pPTS, i);
 
@@ -828,9 +830,8 @@ int32_t firstFunction(SqlFunctionCtx *pCtx) {
 //        DO_UPDATE_TAG_COLUMNS(pCtx, ts);
 
         pResInfo->numOfRes = 1;
+        break;
       }
-
-      numOfElems++;
     }
   } else {
     // in case of descending order time stamp serial, which usually happens as the results of the nest query,
@@ -847,6 +848,8 @@ int32_t firstFunction(SqlFunctionCtx *pCtx) {
         continue;
       }
 
+      numOfElems++;
+
       char* data = colDataGetData(pInputCol, i);
       TSKEY cts = getRowPTs(pInput->pPTS, i);
 
@@ -855,9 +858,8 @@ int32_t firstFunction(SqlFunctionCtx *pCtx) {
         *(TSKEY*)(buf + bytes) = cts;
 //        DO_UPDATE_TAG_COLUMNS(pCtx, ts);
         pResInfo->numOfRes = 1;
+        break;
       }
-
-      numOfElems++;
     }
   }
 
@@ -874,43 +876,55 @@ int32_t lastFunction(SqlFunctionCtx *pCtx) {
   SInputColumnInfoData* pInput = &pCtx->input;
   SColumnInfoData* pInputCol = pInput->pData[0];
 
+  int32_t bytes = pInputCol->info.bytes;
+
   // All null data column, return directly.
   if (pInput->colDataAggIsSet && (pInput->pColumnDataAgg[0]->numOfNull == pInput->totalRows)) {
     ASSERT(pInputCol->hasNull == true);
     return 0;
   }
 
-  if (pCtx->order == TSDB_ORDER_DESC) {
+  SColumnDataAgg* pColAgg = (pInput->colDataAggIsSet)? pInput->pColumnDataAgg[0]:NULL;
+
+  TSKEY startKey = getRowPTs(pInput->pPTS, 0);
+  TSKEY endKey = getRowPTs(pInput->pPTS, pInput->totalRows - 1);
+
+  int32_t blockDataOrder = (startKey <= endKey)? TSDB_ORDER_ASC:TSDB_ORDER_DESC;
+
+  if (blockDataOrder == TSDB_ORDER_ASC) {
     for (int32_t i = pInput->numOfRows + pInput->startRowIndex - 1; i >= pInput->startRowIndex; --i) {
-      if (pInputCol->hasNull && colDataIsNull(pInputCol, pInput->totalRows, i, NULL)) {
+      if (pInputCol->hasNull && colDataIsNull(pInputCol, pInput->totalRows, i, pColAgg)) {
         continue;
       }
 
-      char* data = colDataGetData(pInputCol, i);
-      memcpy(buf, data, pInputCol->info.bytes);
-
-//      TSKEY ts = pCtx->ptsList ? GET_TS_DATA(pCtx, i) : 0;
-//      DO_UPDATE_TAG_COLUMNS(pCtx, ts);
-      pResInfo->complete = true;  // set query completed on this column
       numOfElems++;
+
+      char* data = colDataGetData(pInputCol, i);
+      TSKEY cts = getRowPTs(pInput->pPTS, i);
+      if (pResInfo->numOfRes == 0 || *(TSKEY*)(buf + bytes) > cts) {
+        memcpy(buf, data, bytes);
+        *(TSKEY*)(buf + bytes) = cts;
+        //        DO_UPDATE_TAG_COLUMNS(pCtx, ts);
+        pResInfo->numOfRes = 1;
+      }
       break;
     }
-  } else {  // ascending order
+  } else {  // descending order
     for (int32_t i = pInput->startRowIndex; i < pInput->numOfRows + pInput->startRowIndex; ++i) {
-      if (pInputCol->hasNull && colDataIsNull(pInputCol, pInput->totalRows, i, NULL)) {
+      if (pInputCol->hasNull && colDataIsNull(pInputCol, pInput->totalRows, i, pColAgg)) {
         continue;
       }
 
-      char* data = colDataGetData(pInputCol, i);
-      TSKEY ts = pCtx->ptsList ? GET_TS_DATA(pCtx, i) : 0;
+      numOfElems++;
 
-      if (pResInfo->numOfRes == 0 || (*(TSKEY*)buf) < ts) {
-        memcpy(buf, data, pCtx->inputBytes);
-        *(TSKEY*)buf = ts;
+      char* data = colDataGetData(pInputCol, i);
+      TSKEY cts = getRowPTs(pInput->pPTS, i);
+      if (pResInfo->numOfRes == 0 || *(TSKEY*)(buf + bytes) > cts) {
+        memcpy(buf, data, bytes);
+        *(TSKEY*)(buf + bytes) = cts;
+        pResInfo->numOfRes = 1;
 //        DO_UPDATE_TAG_COLUMNS(pCtx, ts);
       }
-
-      numOfElems++;
       break;
     }
   }