TD-14405 TD-14404 desc and reset query cache statement implement

include/common/ttokendef.h

@@ -138,59 +138,62 @@
 #define TK_INTERVAL                       120
 #define TK_TOPIC                          121
 #define TK_AS                             122
-#define TK_EXPLAIN                        123
-#define TK_ANALYZE                        124
-#define TK_VERBOSE                        125
-#define TK_NK_BOOL                        126
-#define TK_RATIO                          127
-#define TK_NULL                           128
-#define TK_NK_VARIABLE                    129
-#define TK_NK_UNDERLINE                   130
-#define TK_ROWTS                          131
-#define TK_TBNAME                         132
-#define TK_QSTARTTS                       133
-#define TK_QENDTS                         134
-#define TK_WSTARTTS                       135
-#define TK_WENDTS                         136
-#define TK_WDURATION                      137
-#define TK_BETWEEN                        138
-#define TK_IS                             139
-#define TK_NK_LT                          140
-#define TK_NK_GT                          141
-#define TK_NK_LE                          142
-#define TK_NK_GE                          143
-#define TK_NK_NE                          144
-#define TK_MATCH                          145
-#define TK_NMATCH                         146
-#define TK_IN                             147
-#define TK_JOIN                           148
-#define TK_INNER                          149
-#define TK_SELECT                         150
-#define TK_DISTINCT                       151
-#define TK_WHERE                          152
-#define TK_PARTITION                      153
-#define TK_BY                             154
-#define TK_SESSION                        155
-#define TK_STATE_WINDOW                   156
-#define TK_SLIDING                        157
-#define TK_FILL                           158
-#define TK_VALUE                          159
-#define TK_NONE                           160
-#define TK_PREV                           161
-#define TK_LINEAR                         162
-#define TK_NEXT                           163
-#define TK_GROUP                          164
-#define TK_HAVING                         165
-#define TK_ORDER                          166
-#define TK_SLIMIT                         167
-#define TK_SOFFSET                        168
-#define TK_LIMIT                          169
-#define TK_OFFSET                         170
-#define TK_ASC                            171
-#define TK_DESC                           172
-#define TK_NULLS                          173
-#define TK_FIRST                          174
-#define TK_LAST                           175
+#define TK_DESC                           123
+#define TK_DESCRIBE                       124
+#define TK_RESET                          125
+#define TK_QUERY                          126
+#define TK_EXPLAIN                        127
+#define TK_ANALYZE                        128
+#define TK_VERBOSE                        129
+#define TK_NK_BOOL                        130
+#define TK_RATIO                          131
+#define TK_NULL                           132
+#define TK_NK_VARIABLE                    133
+#define TK_NK_UNDERLINE                   134
+#define TK_ROWTS                          135
+#define TK_TBNAME                         136
+#define TK_QSTARTTS                       137
+#define TK_QENDTS                         138
+#define TK_WSTARTTS                       139
+#define TK_WENDTS                         140
+#define TK_WDURATION                      141
+#define TK_BETWEEN                        142
+#define TK_IS                             143
+#define TK_NK_LT                          144
+#define TK_NK_GT                          145
+#define TK_NK_LE                          146
+#define TK_NK_GE                          147
+#define TK_NK_NE                          148
+#define TK_MATCH                          149
+#define TK_NMATCH                         150
+#define TK_IN                             151
+#define TK_JOIN                           152
+#define TK_INNER                          153
+#define TK_SELECT                         154
+#define TK_DISTINCT                       155
+#define TK_WHERE                          156
+#define TK_PARTITION                      157
+#define TK_BY                             158
+#define TK_SESSION                        159
+#define TK_STATE_WINDOW                   160
+#define TK_SLIDING                        161
+#define TK_FILL                           162
+#define TK_VALUE                          163
+#define TK_NONE                           164
+#define TK_PREV                           165
+#define TK_LINEAR                         166
+#define TK_NEXT                           167
+#define TK_GROUP                          168
+#define TK_HAVING                         169
+#define TK_ORDER                          170
+#define TK_SLIMIT                         171
+#define TK_SOFFSET                        172
+#define TK_LIMIT                          173
+#define TK_OFFSET                         174
+#define TK_ASC                            175
+#define TK_NULLS                          176
+#define TK_FIRST                          177
+#define TK_LAST                           178
 
 #define TK_NK_SPACE                       300
 #define TK_NK_COMMENT                     301

include/libs/command/command.h

+/*
+ * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
+ *
+ * This program is free software: you can use, redistribute, and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3
+ * or later ("AGPL"), as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "cmdnodes.h"
+#include "tmsg.h"
+
+int32_t qExecCommand(SNode* pStmt, SRetrieveTableRsp** pRsp);

include/libs/nodes/cmdnodes.h

@@ -20,8 +20,14 @@
 extern "C" {
 #endif
 
+#include "query.h"
 #include "querynodes.h"
 
+#define DESCRIBE_RESULT_COLS 4
+#define DESCRIBE_RESULT_FIELD_LEN (TSDB_COL_NAME_LEN - 1 + VARSTR_HEADER_SIZE)
+#define DESCRIBE_RESULT_TYPE_LEN (20 + VARSTR_HEADER_SIZE)
+#define DESCRIBE_RESULT_NOTE_LEN (8 + VARSTR_HEADER_SIZE)
+
 typedef struct SDatabaseOptions {
   ENodeType type;
   int32_t numOfBlocks;
@@ -247,6 +253,13 @@ typedef struct SAlterLocalStmt {
   char value[TSDB_DNODE_VALUE_LEN];
 } SAlterLocalStmt;
 
+typedef struct SDescribeStmt {
+  ENodeType type;
+  char dbName[TSDB_DB_NAME_LEN];
+  char tableName[TSDB_TABLE_NAME_LEN];
+  STableMeta* pMeta;
+} SDescribeStmt;
+
 #ifdef __cplusplus
 }
 #endif

include/libs/nodes/nodes.h

@@ -101,6 +101,8 @@ typedef enum ENodeType {
   QUERY_NODE_DROP_TOPIC_STMT,
   QUERY_NODE_ALTER_LOCAL_STMT,
   QUERY_NODE_EXPLAIN_STMT,
+  QUERY_NODE_DESCRIBE_STMT,
+  QUERY_NODE_RESET_QUERY_CACHE_STMT,
   QUERY_NODE_SHOW_DATABASES_STMT,
   QUERY_NODE_SHOW_TABLES_STMT,
   QUERY_NODE_SHOW_STABLES_STMT,

include/libs/parser/parser.h

@@ -55,6 +55,7 @@ typedef struct SQuery {
   SArray* pDbList;
   SArray* pTableList;
   bool showRewrite;
+  bool localCmd;
 } SQuery;
 
 int32_t qParseQuerySql(SParseContext* pCxt, SQuery** pQuery);

source/client/CMakeLists.txt

@@ -8,7 +8,7 @@ target_include_directories(
 target_link_libraries(
     taos
     INTERFACE api
-    PRIVATE os util common transport nodes parser planner catalog scheduler function qcom
+    PRIVATE os util common transport nodes parser command planner catalog scheduler function qcom
 )
 
 if(${BUILD_TEST})

source/client/src/clientImpl.c

 
 #include "clientInt.h"
 #include "clientLog.h"
+#include "command.h"
 #include "scheduler.h"
 #include "tdatablock.h"
 #include "tdef.h"
@@ -170,6 +171,15 @@ int32_t parseSql(SRequestObj* pRequest, bool topicQuery, SQuery** pQuery) {
   return code;
 }
 
+int32_t execLocalCmd(SRequestObj* pRequest, SQuery* pQuery) {
+  SRetrieveTableRsp* pRsp = NULL;
+  int32_t code = qExecCommand(pQuery->pRoot, &pRsp);
+  if (TSDB_CODE_SUCCESS == code && NULL != pRsp) {
+    code = setQueryResultFromRsp(&pRequest->body.resInfo, pRsp);
+  }
+  return code;
+}
+
 int32_t execDdlQuery(SRequestObj* pRequest, SQuery* pQuery) {
   SCmdMsgInfo* pMsgInfo = pQuery->pCmdMsg;
   pRequest->type = pMsgInfo->msgType;
@@ -259,7 +269,9 @@ SRequestObj* execQueryImpl(STscObj* pTscObj, const char* sql, int sqlLen) {
   CHECK_CODE_GOTO(buildRequest(pTscObj, sql, sqlLen, &pRequest), _return);
   CHECK_CODE_GOTO(parseSql(pRequest, false, &pQuery), _return);
 
-  if (pQuery->directRpc) {
+  if (pQuery->localCmd) {
+    CHECK_CODE_GOTO(execLocalCmd(pRequest, pQuery), _return);
+  } else if (pQuery->directRpc) {
     CHECK_CODE_GOTO(execDdlQuery(pRequest, pQuery), _return);
   } else {
     CHECK_CODE_GOTO(getPlan(pRequest, pQuery, &pRequest->body.pDag, pNodeList), _return);
@@ -464,9 +476,11 @@ static void destroySendMsgInfo(SMsgSendInfo* pMsgBody) {
   taosMemoryFreeClear(pMsgBody->msgInfo.pData);
   taosMemoryFreeClear(pMsgBody);
 }
+
 bool persistConnForSpecificMsg(void* parenct, tmsg_t msgType) {
   return msgType == TDMT_VND_QUERY_RSP || msgType == TDMT_VND_FETCH_RSP || msgType == TDMT_VND_RES_READY_RSP || msgType == TDMT_VND_QUERY_HEARTBEAT_RSP;
 }
+
 void processMsgFromServer(void* parent, SRpcMsg* pMsg, SEpSet* pEpSet) {
   SMsgSendInfo* pSendInfo = (SMsgSendInfo*)pMsg->ahandle;
   assert(pMsg->ahandle != NULL);
@@ -647,6 +661,11 @@ void* doFetchRow(SRequestObj* pRequest, bool setupOneRowPtr) {
       }
     }
 
+    if (pResultInfo->completed) {
+      pResultInfo->numOfRows = 0;
+      return NULL;
+    }
+
     SMsgSendInfo* body = buildMsgInfoImpl(pRequest);
 
     int64_t  transporterId = 0;

source/libs/CMakeLists.txt

@@ -17,3 +17,4 @@ add_subdirectory(tfs)
 add_subdirectory(monitor)
 add_subdirectory(nodes)
 add_subdirectory(scalar)
+add_subdirectory(command)

source/libs/command/CMakeLists.txt

+aux_source_directory(src COMMAND_SRC)
+add_library(command STATIC ${COMMAND_SRC})
+target_include_directories(
+        command
+        PUBLIC "${CMAKE_SOURCE_DIR}/include/libs/command"
+        PRIVATE "${CMAKE_CURRENT_SOURCE_DIR}/inc"
+)
+
+target_link_libraries(
+        command
+        PRIVATE os util nodes catalog function transport qcom
+)
+
+if(${BUILD_TEST})
+    ADD_SUBDIRECTORY(test)
+endif(${BUILD_TEST})
\ No newline at end of file

source/libs/command/src/command.c

+/*
+ * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
+ *
+ * This program is free software: you can use, redistribute, and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3
+ * or later ("AGPL"), as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "command.h"
+#include "tdatablock.h"
+
+// #define SET_VARSTR(pData, val, pOffset)
+
+static void buildRspData(const STableMeta* pMeta, char* pData) {
+  int32_t* pColSizes = (int32_t*)pData;
+  pData += DESCRIBE_RESULT_COLS * sizeof(int32_t);
+  int32_t numOfRows = TABLE_TOTAL_COL_NUM(pMeta);
+
+  // Field
+  int32_t* pOffset = (int32_t*)pData;
+  pData += numOfRows * sizeof(int32_t);
+  for (int32_t i = 0; i < numOfRows; ++i) {
+    STR_TO_VARSTR(pData, pMeta->schema[i].name);
+    int16_t len = varDataTLen(pData);
+    pData += len;
+    *pOffset = pColSizes[0];
+    pOffset += 1;
+    pColSizes[0] += len;
+  }
+  
+  // Type
+  pOffset = (int32_t*)pData;
+  pData += numOfRows * sizeof(int32_t);
+  for (int32_t i = 0; i < numOfRows; ++i) {
+    STR_TO_VARSTR(pData, tDataTypes[pMeta->schema[i].type].name);
+    int16_t len = varDataTLen(pData);
+    pData += len;
+    *pOffset = pColSizes[1];
+    pOffset += 1;
+    pColSizes[1] += len;
+  }
+
+  // Length
+  pData += BitmapLen(numOfRows);
+  for (int32_t i = 0; i < numOfRows; ++i) {
+    *(int32_t*)pData = pMeta->schema[i].bytes;
+    pData += sizeof(int32_t);
+  }
+  pColSizes[2] = sizeof(int32_t) * numOfRows;
+
+  // Note
+  pOffset = (int32_t*)pData;
+  pData += numOfRows * sizeof(int32_t);
+  for (int32_t i = 0; i < numOfRows; ++i) {
+    STR_TO_VARSTR(pData, i >= pMeta->tableInfo.numOfColumns ? "TAG" : "");
+    int16_t len = varDataTLen(pData);
+    pData += len;
+    *pOffset = pColSizes[3];
+    pOffset += 1;
+    pColSizes[3] += len;
+  }
+
+  for (int32_t i = 0; i < DESCRIBE_RESULT_COLS; ++i) {
+    pColSizes[i] = htonl(pColSizes[i]);
+  }
+}
+
+static int32_t calcRspSize(const STableMeta* pMeta) {
+  int32_t numOfRows = TABLE_TOTAL_COL_NUM(pMeta);
+  return sizeof(SRetrieveTableRsp) + 
+      (numOfRows * sizeof(int32_t) + numOfRows * DESCRIBE_RESULT_FIELD_LEN) + 
+      (numOfRows * sizeof(int32_t) + numOfRows * DESCRIBE_RESULT_TYPE_LEN) +
+      (BitmapLen(numOfRows) + numOfRows * sizeof(int32_t)) + 
+      (numOfRows * sizeof(int32_t) + numOfRows * DESCRIBE_RESULT_NOTE_LEN);
+}
+
+static int32_t execDescribe(SNode* pStmt, SRetrieveTableRsp** pRsp) {
+  SDescribeStmt* pDesc = (SDescribeStmt*)pStmt;
+  *pRsp = taosMemoryCalloc(1, calcRspSize(pDesc->pMeta));
+  if (NULL == *pRsp) {
+    return TSDB_CODE_OUT_OF_MEMORY;
+  }
+  (*pRsp)->useconds = 0;
+  (*pRsp)->completed = 1;
+  (*pRsp)->precision = 0;
+  (*pRsp)->compressed = 0;
+  (*pRsp)->compLen = 0;
+  (*pRsp)->numOfRows = htonl(TABLE_TOTAL_COL_NUM(pDesc->pMeta));
+  buildRspData(pDesc->pMeta, (*pRsp)->data);
+  return TSDB_CODE_SUCCESS;
+}
+
+static int32_t execResetQueryCache() {
+  // todo
+  return TSDB_CODE_SUCCESS;
+}
+
+int32_t qExecCommand(SNode* pStmt, SRetrieveTableRsp** pRsp) {
+  switch (nodeType(pStmt)) {
+    case QUERY_NODE_DESCRIBE_STMT:
+      return execDescribe(pStmt, pRsp);
+    case QUERY_NODE_RESET_QUERY_CACHE_STMT:
+      return execResetQueryCache();
+    default:
+      break;
+  }
+  return TSDB_CODE_FAILED;
+}

source/libs/command/test/CMakeLists.txt

+MESSAGE(STATUS "build command unit test")
+
+# GoogleTest requires at least C++11
+SET(CMAKE_CXX_STANDARD 11)
+AUX_SOURCE_DIRECTORY(${CMAKE_CURRENT_SOURCE_DIR} SOURCE_LIST)
+
+ADD_EXECUTABLE(commandTest ${SOURCE_LIST})
+
+TARGET_INCLUDE_DIRECTORIES(
+        commandTest
+        PUBLIC "${CMAKE_SOURCE_DIR}/include/libs/command/"
+        PRIVATE "${CMAKE_SOURCE_DIR}/source/libs/command/inc"
+)
+
+TARGET_LINK_LIBRARIES(
+        commandTest
+        PUBLIC os util common nodes parser catalog transport gtest function qcom
+)
\ No newline at end of file

source/libs/command/test/commandTest.cpp

+/*
+ * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
+ *
+ * This program is free software: you can use, redistribute, and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3
+ * or later ("AGPL"), as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <gtest/gtest.h>
+
+int main(int argc, char* argv[]) {
+	testing::InitGoogleTest(&argc, argv);
+	return RUN_ALL_TESTS();
+}

source/libs/nodes/src/nodesUtilFuncs.c

@@ -136,6 +136,10 @@ SNodeptr nodesMakeNode(ENodeType type) {
       return makeNode(type, sizeof(SDropTopicStmt));
     case QUERY_NODE_EXPLAIN_STMT:
       return makeNode(type, sizeof(SExplainStmt));
+    case QUERY_NODE_DESCRIBE_STMT:
+      return makeNode(type, sizeof(SDescribeStmt));
+    case QUERY_NODE_RESET_QUERY_CACHE_STMT:
+      return makeNode(type, sizeof(SNode));
     case QUERY_NODE_SHOW_DATABASES_STMT:
     case QUERY_NODE_SHOW_TABLES_STMT:
     case QUERY_NODE_SHOW_STABLES_STMT:

source/libs/parser/inc/parAst.h

@@ -163,6 +163,8 @@ SNode* createDefaultExplainOptions(SAstCreateContext* pCxt);
 SNode* setExplainVerbose(SAstCreateContext* pCxt, SNode* pOptions, const SToken* pVal);
 SNode* setExplainRatio(SAstCreateContext* pCxt, SNode* pOptions, const SToken* pVal);
 SNode* createExplainStmt(SAstCreateContext* pCxt, bool analyze, SNode* pOptions, SNode* pQuery);
+SNode* createDescribeStmt(SAstCreateContext* pCxt, SNode* pRealTable);
+SNode* createResetQueryCacheStmt(SAstCreateContext* pCxt);
 
 #ifdef __cplusplus
 }

source/libs/parser/inc/parInt.h

@@ -25,6 +25,7 @@ extern "C" {
 int32_t parseInsertSql(SParseContext* pContext, SQuery** pQuery);
 int32_t doParse(SParseContext* pParseCxt, SQuery** pQuery);
 int32_t doTranslate(SParseContext* pParseCxt, SQuery* pQuery);
+int32_t extractResultSchema(const SNode* pRoot, int32_t* numOfCols, SSchema** pSchema);
 
 #ifdef __cplusplus
 }

source/libs/parser/inc/sql.y

@@ -339,7 +339,14 @@ cmd ::= CREATE TOPIC not_exists_opt(A) topic_name(B) AS query_expression(C).
 cmd ::= CREATE TOPIC not_exists_opt(A) topic_name(B) AS db_name(C).               { pCxt->pRootNode = createCreateTopicStmt(pCxt, A, &B, NULL, &C); }
 cmd ::= DROP TOPIC exists_opt(A) topic_name(B).                                   { pCxt->pRootNode = createDropTopicStmt(pCxt, A, &B); }
 
-/************************************************ select **************************************************************/
+/************************************************ desc/describe *******************************************************/
+cmd ::= DESC full_table_name(A).                                                  { pCxt->pRootNode = createDescribeStmt(pCxt, A); }
+cmd ::= DESCRIBE full_table_name(A).                                              { pCxt->pRootNode = createDescribeStmt(pCxt, A); }
+
+/************************************************ reset query cache ***************************************************/
+cmd ::= RESET QUERY CACHE.                                                        { pCxt->pRootNode = createResetQueryCacheStmt(pCxt); }
+
+/************************************************ explain *************************************************************/
 cmd ::= EXPLAIN analyze_opt(A) explain_options(B) query_expression(C).            { pCxt->pRootNode = createExplainStmt(pCxt, A, B, C); }
 
 %type analyze_opt                                                                 { bool }

source/libs/parser/src/parAstCreater.c

@@ -1343,3 +1343,18 @@ SNode* createExplainStmt(SAstCreateContext* pCxt, bool analyze, SNode* pOptions,
   pStmt->pQuery = pQuery;
   return (SNode*)pStmt;
 }
+
+SNode* createDescribeStmt(SAstCreateContext* pCxt, SNode* pRealTable) {
+  SDescribeStmt* pStmt = nodesMakeNode(QUERY_NODE_DESCRIBE_STMT);
+  CHECK_OUT_OF_MEM(pStmt);
+  strcpy(pStmt->dbName, ((SRealTableNode*)pRealTable)->table.dbName);
+  strcpy(pStmt->tableName, ((SRealTableNode*)pRealTable)->table.tableName);
+  nodesDestroyNode(pRealTable);
+  return (SNode*)pStmt;
+}
+
+SNode* createResetQueryCacheStmt(SAstCreateContext* pCxt) {
+  SNode* pStmt = nodesMakeNode(QUERY_NODE_RESET_QUERY_CACHE_STMT);
+  CHECK_OUT_OF_MEM(pStmt);
+  return pStmt;
+}

source/libs/parser/src/parTokenizer.c

@@ -51,6 +51,7 @@ static SKeyword keywordTable[] = {
     {"DAYS",          TK_DAYS},
     {"DELAY",         TK_DELAY},
     {"DESC",          TK_DESC},
+    {"DESCRIBE",      TK_DESCRIBE},
     {"DISTINCT",      TK_DISTINCT},
     {"DNODE",         TK_DNODE},
     {"DNODES",        TK_DNODES},
@@ -111,9 +112,11 @@ static SKeyword keywordTable[] = {
     {"QNODE",         TK_QNODE},
     {"QNODES",        TK_QNODES},
     {"QSTARTTS",      TK_QSTARTTS},
+    {"QUERY",         TK_QUERY},
     {"QUORUM",        TK_QUORUM},
     {"RATIO",         TK_RATIO},
     {"REPLICA",       TK_REPLICA},
+    {"RESET",         TK_RESET},
     {"RETENTIONS",    TK_RETENTIONS},
     {"ROLLUP",        TK_ROLLUP},
     {"ROWTS",         TK_ROWTS},
@@ -186,7 +189,6 @@ static SKeyword keywordTable[] = {
     // {"SCORES",       TK_SCORES},
     // {"GRANTS",       TK_GRANTS},
     // {"DOT",          TK_DOT},
-    // {"DESCRIBE",     TK_DESCRIBE},
     // {"SYNCDB",       TK_SYNCDB},
     // {"LOCAL",        TK_LOCAL},
     // {"PPS",          TK_PPS},
@@ -203,8 +205,6 @@ static SKeyword keywordTable[] = {
     // {"EVERY",        TK_EVERY},
     // {"VARIABLE",     TK_VARIABLE},
     // {"UPDATE",       TK_UPDATE},
-    // {"RESET",        TK_RESET},
-    // {"QUERY",        TK_QUERY},
     // {"ADD",          TK_ADD},
     // {"COLUMN",       TK_COLUMN},
     // {"TAG",          TK_TAG},

source/libs/parser/src/parTranslater.c

@@ -1812,6 +1812,10 @@ static int32_t translateExplain(STranslateContext* pCxt, SExplainStmt* pStmt) {
   return translateQuery(pCxt, pStmt->pQuery);
 }
 
+static int32_t translateDescribe(STranslateContext* pCxt, SDescribeStmt* pStmt) {
+  return getTableMeta(pCxt, pStmt->dbName, pStmt->tableName, &pStmt->pMeta);
+}
+
 static int32_t translateQuery(STranslateContext* pCxt, SNode* pNode) {
   int32_t code = TSDB_CODE_SUCCESS;
   switch (nodeType(pNode)) {
@@ -1896,6 +1900,9 @@ static int32_t translateQuery(STranslateContext* pCxt, SNode* pNode) {
     case QUERY_NODE_EXPLAIN_STMT:
       code = translateExplain(pCxt, (SExplainStmt*)pNode);
       break;
+    case QUERY_NODE_DESCRIBE_STMT:
+      code = translateDescribe(pCxt, (SDescribeStmt*)pNode);
+      break;
     default:
       break;
   }
@@ -1913,13 +1920,7 @@ static int32_t translateSubquery(STranslateContext* pCxt, SNode* pNode) {
   return code;
 }
 
-int32_t qExtractResultSchema(const SNode* pRoot, int32_t* numOfCols, SSchema** pSchema) {
-  if (NULL == pRoot) {
-    return TSDB_CODE_SUCCESS;
-  }
-
-  if (QUERY_NODE_SELECT_STMT == nodeType(pRoot)) {
-    SSelectStmt* pSelect = (SSelectStmt*) pRoot;
+static int32_t extractSelectResultSchema(const SSelectStmt* pSelect, int32_t* numOfCols, SSchema** pSchema) {
   *numOfCols = LIST_LENGTH(pSelect->pProjectionList);
   *pSchema = taosMemoryCalloc((*numOfCols), sizeof(SSchema));
   if (NULL == (*pSchema)) {
@@ -1936,7 +1937,11 @@ int32_t qExtractResultSchema(const SNode* pRoot, int32_t* numOfCols, SSchema** p
     strcpy((*pSchema)[index].name, pExpr->aliasName);
     index +=1;
   }
-  } else if (QUERY_NODE_EXPLAIN_STMT == nodeType(pRoot)) {
+
+  return TSDB_CODE_SUCCESS;
+}
+
+static int32_t extractExplainResultSchema(int32_t* numOfCols, SSchema** pSchema) {
   *numOfCols = 1;
   *pSchema = taosMemoryCalloc((*numOfCols), sizeof(SSchema));
   if (NULL == (*pSchema)) {
@@ -1944,11 +1949,54 @@ int32_t qExtractResultSchema(const SNode* pRoot, int32_t* numOfCols, SSchema** p
   }
   (*pSchema)[0].type = TSDB_DATA_TYPE_BINARY;
   (*pSchema)[0].bytes = TSDB_EXPLAIN_RESULT_ROW_SIZE;
+  return TSDB_CODE_SUCCESS;
+}
+
+static int32_t extractDescribeResultSchema(int32_t* numOfCols, SSchema** pSchema) {
+  *numOfCols = DESCRIBE_RESULT_COLS;
+  *pSchema = taosMemoryCalloc((*numOfCols), sizeof(SSchema));
+  if (NULL == (*pSchema)) {
+    return TSDB_CODE_OUT_OF_MEMORY;
   }
 
+  (*pSchema)[0].type = TSDB_DATA_TYPE_BINARY;
+  (*pSchema)[0].bytes = DESCRIBE_RESULT_FIELD_LEN;
+  strcpy((*pSchema)[0].name, "Field");
+
+  (*pSchema)[1].type = TSDB_DATA_TYPE_BINARY;
+  (*pSchema)[1].bytes = DESCRIBE_RESULT_TYPE_LEN;
+  strcpy((*pSchema)[1].name, "Type");
+
+  (*pSchema)[2].type = TSDB_DATA_TYPE_INT;
+  (*pSchema)[2].bytes = tDataTypes[TSDB_DATA_TYPE_INT].bytes;
+  strcpy((*pSchema)[2].name, "Length");
+
+  (*pSchema)[3].type = TSDB_DATA_TYPE_BINARY;
+  (*pSchema)[3].bytes = DESCRIBE_RESULT_NOTE_LEN;
+  strcpy((*pSchema)[3].name, "Note");
+
   return TSDB_CODE_SUCCESS;
 }
 
+int32_t extractResultSchema(const SNode* pRoot, int32_t* numOfCols, SSchema** pSchema) {
+  if (NULL == pRoot) {
+    return TSDB_CODE_SUCCESS;
+  }
+
+  switch (nodeType(pRoot)) {
+    case QUERY_NODE_SELECT_STMT:
+      return extractSelectResultSchema((SSelectStmt*)pRoot, numOfCols, pSchema);
+    case QUERY_NODE_EXPLAIN_STMT:
+      return extractExplainResultSchema(numOfCols, pSchema);
+    case QUERY_NODE_DESCRIBE_STMT:
+      return extractDescribeResultSchema(numOfCols, pSchema);
+    default:
+      break;
+  }
+
+  return TSDB_CODE_FAILED;
+}
+
 static void destroyTranslateContext(STranslateContext* pCxt) {
   if (NULL != pCxt->pNsLevel) {
     size_t size = taosArrayGetSize(pCxt->pNsLevel);
@@ -2530,26 +2578,31 @@ static int32_t setQuery(STranslateContext* pCxt, SQuery* pQuery) {
     case QUERY_NODE_SELECT_STMT:
     case QUERY_NODE_EXPLAIN_STMT:
       pQuery->haveResultSet = true;
-      pQuery->directRpc = false;
       pQuery->msgType = TDMT_VND_QUERY;
-      if (TSDB_CODE_SUCCESS != qExtractResultSchema(pQuery->pRoot, &pQuery->numOfResCols, &pQuery->pResSchema)) {
-        return TSDB_CODE_OUT_OF_MEMORY;
-      }
       break;
     case QUERY_NODE_VNODE_MODIF_STMT:
-      pQuery->haveResultSet = false;
-      pQuery->directRpc = false;
       pQuery->msgType = TDMT_VND_CREATE_TABLE;
       break;
+    case QUERY_NODE_DESCRIBE_STMT:
+      pQuery->localCmd = true;
+      pQuery->haveResultSet = true;
+      break;
+    case QUERY_NODE_RESET_QUERY_CACHE_STMT:
+      pQuery->localCmd = true;
+      break;
     default:
-      pQuery->haveResultSet = false;
       pQuery->directRpc = true;
-      pQuery->pCmdMsg = pCxt->pCmdMsg;
-      pCxt->pCmdMsg = NULL;
+      TSWAP(pQuery->pCmdMsg, pCxt->pCmdMsg, SCmdMsgInfo*);
       pQuery->msgType = pQuery->pCmdMsg->msgType;
       break;
   }
 
+  if (pQuery->haveResultSet) {
+    if (TSDB_CODE_SUCCESS != extractResultSchema(pQuery->pRoot, &pQuery->numOfResCols, &pQuery->pResSchema)) {
+      return TSDB_CODE_OUT_OF_MEMORY;
+    }
+  }
+  
   if (NULL != pCxt->pDbs) {
     pQuery->pDbList = taosArrayInit(taosHashGetSize(pCxt->pDbs), TSDB_DB_FNAME_LEN);
     if (NULL == pQuery->pDbList) {

source/libs/parser/src/parser.c

@@ -62,3 +62,7 @@ void qDestroyQuery(SQuery* pQueryNode) {
   taosArrayDestroy(pQueryNode->pTableList);
   taosMemoryFreeClear(pQueryNode);
 }
+
+int32_t qExtractResultSchema(const SNode* pRoot, int32_t* numOfCols, SSchema** pSchema) {
+  return extractResultSchema(pRoot, numOfCols, pSchema);
+}
\ No newline at end of file

source/libs/planner/src/planPhysiCreater.c

@@ -719,6 +719,9 @@ static int32_t createStreamScanPhysiNodeByExchange(SPhysiPlanContext* pCxt, SExc
   if (NULL == pScan->pScanCols) {
     code = TSDB_CODE_OUT_OF_MEMORY;
   }
+  if (TSDB_CODE_SUCCESS == code) {
+    code = sortScanCols(pScan->pScanCols);
+  }
   if (TSDB_CODE_SUCCESS == code) {
     code = addDataBlockSlots(pCxt, pScan->pScanCols, pScan->node.pOutputDataBlockDesc);
   }