Merge pull request #4825 from taosdata/feature/query

Feature/query

src/client/src/tscSQLParser.c

@@ -4599,7 +4599,7 @@ int32_t parseOrderbyClause(SSqlCmd* pCmd, SQueryInfo* pQueryInfo, SQuerySQL* pQu
   const char* msg0 = "only support order by primary timestamp";
   const char* msg1 = "invalid column name";
   const char* msg2 = "only support order by primary timestamp or queried column";
-  const char* msg3 = "only support order by primary timestamp or first tag in groupby clause";
+  const char* msg3 = "invalid column in order by clause, only primary timestamp or first tag in groupby clause allowed";
 
   setDefaultOrderInfo(pQueryInfo);
   STableMetaInfo* pTableMetaInfo = tscGetMetaInfo(pQueryInfo, 0);
@@ -5279,8 +5279,7 @@ int32_t parseLimitClause(SSqlCmd* pCmd, SQueryInfo* pQueryInfo, int32_t clauseIn
 
   const char* msg0 = "soffset/offset can not be less than 0";
   const char* msg1 = "slimit/soffset only available for STable query";
-  const char* msg2 = "functions mixed up in table query";
-  const char* msg3 = "slimit/soffset can not apply to projection query";
+  const char* msg2 = "slimit/soffset can not apply to projection query";
 
   // handle the limit offset value, validate the limit
   pQueryInfo->limit = pQuerySql->limit;
@@ -5305,7 +5304,7 @@ int32_t parseLimitClause(SSqlCmd* pCmd, SQueryInfo* pQueryInfo, int32_t clauseIn
     if (!tscQueryTags(pQueryInfo)) {  // local handle the super table tag query
       if (tscIsProjectionQueryOnSTable(pQueryInfo, 0)) {
         if (pQueryInfo->slimit.limit > 0 || pQueryInfo->slimit.offset > 0) {
-          return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg3);
+          return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg2);
         }
 
         // for projection query on super table, all queries are subqueries
@@ -5363,24 +5362,6 @@ int32_t parseLimitClause(SSqlCmd* pCmd, SQueryInfo* pQueryInfo, int32_t clauseIn
     if (pQueryInfo->slimit.limit != -1 || pQueryInfo->slimit.offset != 0) {
       return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg1);
     }
-  
-    size_t size = taosArrayGetSize(pQueryInfo->exprList);
-    
-    bool hasTags = false;
-    bool hasOtherFunc = false;
-    // filter the query functions operating on "tbname" column that are not supported by normal columns.
-    for (int32_t i = 0; i < size; ++i) {
-      SSqlExpr* pExpr = tscSqlExprGet(pQueryInfo, i);
-      if (TSDB_COL_IS_TAG(pExpr->colInfo.flag)) {
-        hasTags = true;
-      } else {
-        hasOtherFunc = true;
-      }
-    }
-    
-    if (hasTags && hasOtherFunc) {
-      return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg2);
-    }
   }
 
   return TSDB_CODE_SUCCESS;
@@ -6282,10 +6263,12 @@ int32_t doCheckForCreateFromStable(SSqlObj* pSql, SSqlInfo* pInfo) {
 
 int32_t doCheckForStream(SSqlObj* pSql, SSqlInfo* pInfo) {
   const char* msg1 = "invalid table name";
+  const char* msg2 = "functions not allowed in CQ";
   const char* msg3 = "fill only available for interval query";
   const char* msg4 = "fill option not supported in stream computing";
   const char* msg5 = "sql too long";  // todo ADD support
   const char* msg6 = "from missing in subclause";
+  const char* msg7 = "time interval is required";
   
   SSqlCmd*    pCmd = &pSql->cmd;
   SQueryInfo* pQueryInfo = tscGetQueryInfoDetail(pCmd, 0);
@@ -6295,10 +6278,10 @@ int32_t doCheckForStream(SSqlObj* pSql, SSqlInfo* pInfo) {
   STableMetaInfo*  pTableMetaInfo = tscGetMetaInfo(pQueryInfo, 0);
 
   // if sql specifies db, use it, otherwise use default db
-  SStrToken* pzTableName = &(pCreateTable->name);
+  SStrToken* pName = &(pCreateTable->name);
   SQuerySQL* pQuerySql = pCreateTable->pSelect;
 
-  if (tscValidateName(pzTableName) != TSDB_CODE_SUCCESS) {
+  if (tscValidateName(pName) != TSDB_CODE_SUCCESS) {
     return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg1);
   }
   
@@ -6337,15 +6320,19 @@ int32_t doCheckForStream(SSqlObj* pSql, SSqlInfo* pInfo) {
   // set interval value
   if (parseIntervalClause(pSql, pQueryInfo, pQuerySql) != TSDB_CODE_SUCCESS) {
     return TSDB_CODE_TSC_INVALID_SQL;
-  } else {
-    if ((pQueryInfo->interval.interval > 0) &&
-        (validateFunctionsInIntervalOrGroupbyQuery(pCmd, pQueryInfo) != TSDB_CODE_SUCCESS)) {
-      return TSDB_CODE_TSC_INVALID_SQL;
-    }
+  }
+
+  if ((pQueryInfo->interval.interval > 0) &&
+      (validateFunctionsInIntervalOrGroupbyQuery(pCmd, pQueryInfo) != TSDB_CODE_SUCCESS)) {
+    return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg2);
+  }
+
+  if (!tscIsProjectionQuery(pQueryInfo) && pQueryInfo->interval.interval == 0) {
+    return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg7);
   }
 
   // set the created table[stream] name
-  code = tscSetTableFullName(pTableMetaInfo, pzTableName, pSql);
+  code = tscSetTableFullName(pTableMetaInfo, pName, pSql);
   if (code != TSDB_CODE_SUCCESS) {
     return code;
   }

src/client/src/tscStream.c

@@ -65,44 +65,51 @@ static int64_t tscGetRetryDelayTime(SSqlStream* pStream, int64_t slidingTime, in
   return retryDelta;
 }
 
-static void tscProcessStreamLaunchQuery(SSchedMsg *pMsg) {
-  SSqlStream *pStream = (SSqlStream *)pMsg->ahandle;
-  SSqlObj *   pSql = pStream->pSql;
+static void doLaunchQuery(void* param, TAOS_RES* tres, int32_t code) {
+  SSqlStream *pStream = (SSqlStream *)param;
+  assert(pStream->pSql == tres && code == TSDB_CODE_SUCCESS);
 
-  pSql->fp = tscProcessStreamQueryCallback;
-  pSql->fetchFp = tscProcessStreamQueryCallback;
-  pSql->param = pStream;
+  SSqlObj* pSql = (SSqlObj*) tres;
+  pSql->fp = doLaunchQuery;
+  pSql->fetchFp = doLaunchQuery;
   pSql->res.completed = false;
-  
+
   SQueryInfo *pQueryInfo = tscGetQueryInfoDetail(&pSql->cmd, 0);
   STableMetaInfo *pTableMetaInfo = tscGetMetaInfo(pQueryInfo, 0);
 
-  int code = tscGetTableMeta(pSql, pTableMetaInfo);
-  pSql->res.code = code;
-
+  code = tscGetTableMeta(pSql, pTableMetaInfo);
   if (code == 0 && UTIL_TABLE_IS_SUPER_TABLE(pTableMetaInfo)) {
     code = tscGetSTableVgroupInfo(pSql, 0);
-    pSql->res.code = code;
   }
 
-  // failed to get meter/metric meta, retry in 10sec.
-  if (code != TSDB_CODE_SUCCESS) {
-    int64_t retryDelayTime = tscGetRetryDelayTime(pStream, pStream->interval.sliding, pStream->precision);
-    tscDebug("%p stream:%p,get metermeta failed, retry in %" PRId64 "ms", pStream->pSql, pStream, retryDelayTime);
-    tscSetRetryTimer(pStream, pSql, retryDelayTime);
-
-  } else {
+  // failed to get table Meta or vgroup list, retry in 10sec.
+  if (code == TSDB_CODE_SUCCESS) {
     tscTansformSQLFuncForSTableQuery(pQueryInfo);
-    tscDebug("%p stream:%p start stream query on:%s", pSql, pStream, pTableMetaInfo->name);
-    tscDoQuery(pStream->pSql);
+    tscDebug("%p stream:%p, start stream query on:%s", pSql, pStream, pTableMetaInfo->name);
+
+    pSql->fp = tscProcessStreamQueryCallback;
+    pSql->fetchFp = tscProcessStreamQueryCallback;
+    tscDoQuery(pSql);
     tscIncStreamExecutionCount(pStream);
+  } else if (code != TSDB_CODE_TSC_ACTION_IN_PROGRESS) {
+    pSql->res.code = code;
+    int64_t retryDelayTime = tscGetRetryDelayTime(pStream, pStream->interval.sliding, pStream->precision);
+    tscDebug("%p stream:%p, get table Meta failed, retry in %" PRId64 "ms", pSql, pStream, retryDelayTime);
+    tscSetRetryTimer(pStream, pSql, retryDelayTime);
   }
 }
 
+static void tscProcessStreamLaunchQuery(SSchedMsg *pMsg) {
+  SSqlStream *pStream = (SSqlStream *)pMsg->ahandle;
+  doLaunchQuery(pStream, pStream->pSql, 0);
+}
+
 static void tscProcessStreamTimer(void *handle, void *tmrId) {
   SSqlStream *pStream = (SSqlStream *)handle;
-  if (pStream == NULL) return;
-  if (pStream->pTimer != tmrId) return;
+  if (pStream == NULL || pStream->pTimer != tmrId) {
+    return;
+  }
+
   pStream->pTimer = NULL;
 
   pStream->numOfRes = 0;  // reset the numOfRes.
@@ -392,11 +399,16 @@ static void tscSetNextLaunchTimer(SSqlStream *pStream, SSqlObj *pSql) {
   tscSetRetryTimer(pStream, pSql, timer);
 }
 
-static void tscSetSlidingWindowInfo(SSqlObj *pSql, SSqlStream *pStream) {
+static int32_t tscSetSlidingWindowInfo(SSqlObj *pSql, SSqlStream *pStream) {
   int64_t minIntervalTime =
       (pStream->precision == TSDB_TIME_PRECISION_MICRO) ? tsMinIntervalTime * 1000L : tsMinIntervalTime;
   
   SQueryInfo* pQueryInfo = tscGetQueryInfoDetail(&pSql->cmd, 0);
+
+  if (!pStream->isProject && pQueryInfo->interval.interval == 0) {
+    sprintf(pSql->cmd.payload, "the interval value is 0");
+    return -1;
+  }
   
   if (pQueryInfo->interval.intervalUnit != 'n' && pQueryInfo->interval.intervalUnit!= 'y' && pQueryInfo->interval.interval < minIntervalTime) {
     tscWarn("%p stream:%p, original sample interval:%" PRId64 " too small, reset to:%" PRId64, pSql, pStream,
@@ -436,6 +448,8 @@ static void tscSetSlidingWindowInfo(SSqlObj *pSql, SSqlStream *pStream) {
     pQueryInfo->interval.interval = 0; // clear the interval value to avoid the force time window split by query processor
     pQueryInfo->interval.sliding = 0;
   }
+
+  return TSDB_CODE_SUCCESS;
 }
 
 static int64_t tscGetStreamStartTimestamp(SSqlObj *pSql, SSqlStream *pStream, int64_t stime) {
@@ -485,34 +499,19 @@ static int64_t tscGetLaunchTimestamp(const SSqlStream *pStream) {
   return (pStream->precision == TSDB_TIME_PRECISION_MICRO) ? timer / 1000L : timer;
 }
 
-static void setErrorInfo(SSqlObj* pSql, int32_t code, char* info) {
-  if (pSql == NULL) {
-    return;
-  }
-
-  SSqlCmd* pCmd = &pSql->cmd;
-
-  pSql->res.code = code;
-  
-  if (info != NULL) {
-    strncpy(pCmd->payload, info, pCmd->payloadLen);
-  }
-}
-
 static void tscCreateStream(void *param, TAOS_RES *res, int code) {
   SSqlStream* pStream = (SSqlStream*)param;
   SSqlObj* pSql = pStream->pSql;
   SSqlCmd* pCmd = &pSql->cmd;
 
   if (code != TSDB_CODE_SUCCESS) {
-    setErrorInfo(pSql, code, pCmd->payload);
-    tscError("%p open stream failed, sql:%s, reason:%s, code:0x%08x", pSql, pSql->sqlstr, pCmd->payload, code);
+    pSql->res.code = code;
+    tscError("%p open stream failed, sql:%s, reason:%s, code:%s", pSql, pSql->sqlstr, pCmd->payload, tstrerror(code));
+
     pStream->fp(pStream->param, NULL, NULL);
     return;
   }
 
-  registerSqlObj(pSql);
-
   SQueryInfo* pQueryInfo = tscGetQueryInfoDetail(pCmd, 0);
   STableMetaInfo* pTableMetaInfo = tscGetMetaInfo(pQueryInfo, 0);
   STableComInfo tinfo = tscGetTableInfo(pTableMetaInfo->pTableMeta);
@@ -523,13 +522,22 @@ static void tscCreateStream(void *param, TAOS_RES *res, int code) {
   pStream->ctime = taosGetTimestamp(pStream->precision);
   pStream->etime = pQueryInfo->window.ekey;
 
-  tscAddIntoStreamList(pStream);
+  if (tscSetSlidingWindowInfo(pSql, pStream) != TSDB_CODE_SUCCESS) {
+    pSql->res.code = code;
+
+    tscError("%p stream %p open failed, since the interval value is incorrect", pSql, pStream);
+    pStream->fp(pStream->param, NULL, NULL);
+    return;
+  }
 
-  tscSetSlidingWindowInfo(pSql, pStream);
   pStream->stime = tscGetStreamStartTimestamp(pSql, pStream, pStream->stime);
 
   int64_t starttime = tscGetLaunchTimestamp(pStream);
   pCmd->command = TSDB_SQL_SELECT;
+
+  registerSqlObj(pSql);
+  tscAddIntoStreamList(pStream);
+
   taosTmrReset(tscProcessStreamTimer, (int32_t)starttime, pStream, tscTmr, &pStream->pTimer);
 
   tscDebug("%p stream:%p is opened, query on:%s, interval:%" PRId64 ", sliding:%" PRId64 ", first launched in:%" PRId64 ", sql:%s", pSql,

src/client/src/tscSubquery.c

@@ -2094,6 +2094,13 @@ static SSqlObj *tscCreateSTableSubquery(SSqlObj *pSql, SRetrieveSupport *trsuppo
 }
 
 void tscRetrieveDataRes(void *param, TAOS_RES *tres, int code) {
+  // the param may be null, since it may be done by other query threads. and the asyncOnError may enter in this
+  // function while kill query by a user.
+  if (param == NULL) {
+    assert(code != TSDB_CODE_SUCCESS);
+    return;
+  }
+
   SRetrieveSupport *trsupport = (SRetrieveSupport *) param;
   
   SSqlObj*  pParentSql = trsupport->pParentSql;

src/query/inc/qExecutor.h

@@ -152,7 +152,7 @@ typedef struct SQuery {
   int16_t          precision;
   int16_t          numOfOutput;
   int16_t          fillType;
-  int16_t          checkBuffer;  // check if the buffer is full during scan each block
+  int16_t          checkResultBuf;  // check if the buffer is full during scan each block
   SLimitVal        limit;
   int32_t          rowSize;
   SSqlGroupbyExpr* pGroupbyExpr;

src/query/src/qExecutor.c

@@ -1708,7 +1708,7 @@ static int32_t tableApplyFunctionsOnBlock(SQueryRuntimeEnv *pRuntimeEnv, SDataBl
     numOfRes = (int32_t) getNumOfResult(pRuntimeEnv);
 
     // update the number of output result
-    if (numOfRes > 0 && pQuery->checkBuffer == 1) {
+    if (numOfRes > 0 && pQuery->checkResultBuf == 1) {
       assert(numOfRes >= pQuery->rec.rows);
       pQuery->rec.rows = numOfRes;
 
@@ -2222,9 +2222,9 @@ void getAlignQueryTimeWindow(SQuery *pQuery, int64_t key, int64_t keyFirst, int6
 
 static void setScanLimitationByResultBuffer(SQuery *pQuery) {
   if (isTopBottomQuery(pQuery)) {
-    pQuery->checkBuffer = 0;
+    pQuery->checkResultBuf = 0;
   } else if (isGroupbyNormalCol(pQuery->pGroupbyExpr)) {
-    pQuery->checkBuffer = 0;
+    pQuery->checkResultBuf = 0;
   } else {
     bool hasMultioutput = false;
     for (int32_t i = 0; i < pQuery->numOfOutput; ++i) {
@@ -2239,7 +2239,7 @@ static void setScanLimitationByResultBuffer(SQuery *pQuery) {
       }
     }
 
-    pQuery->checkBuffer = hasMultioutput ? 1 : 0;
+    pQuery->checkResultBuf = hasMultioutput ? 1 : 0;
   }
 }
 
@@ -2911,7 +2911,7 @@ void setTagVal(SQueryRuntimeEnv *pRuntimeEnv, void *pTable, void *tsdb) {
   SQInfo* pQInfo = GET_QINFO_ADDR(pRuntimeEnv);
 
   SExprInfo *pExprInfo = &pQuery->pExpr1[0];
-  if (pQuery->numOfOutput == 1 && pExprInfo->base.functionId == TSDB_FUNC_TS_COMP) {
+  if (pQuery->numOfOutput == 1 && pExprInfo->base.functionId == TSDB_FUNC_TS_COMP && pRuntimeEnv->stableQuery) {
     assert(pExprInfo->base.numOfParams == 1);
 
     int16_t tagColId = (int16_t)pExprInfo->base.arg->argValue.i64;
@@ -3674,6 +3674,10 @@ void scanOneTableDataBlocks(SQueryRuntimeEnv *pRuntimeEnv, TSKEY start) {
   SQueryStatusInfo qstatus = getQueryStatusInfo(pRuntimeEnv, start);
   SET_MASTER_SCAN_FLAG(pRuntimeEnv);
 
+  if (!pRuntimeEnv->groupbyColumn && pRuntimeEnv->hasTagResults) {
+    setTagVal(pRuntimeEnv, pTableQueryInfo->pTable, pQInfo->tsdb);
+  }
+
   while (1) {
     doScanAllDataBlocks(pRuntimeEnv);
 
@@ -4757,20 +4761,21 @@ static void enableExecutionForNextTable(SQueryRuntimeEnv *pRuntimeEnv) {
   }
 }
 
+// TODO refactor: setAdditionalInfo
 static FORCE_INLINE void setEnvForEachBlock(SQInfo* pQInfo, STableQueryInfo* pTableQueryInfo, SDataBlockInfo* pBlockInfo) {
   SQueryRuntimeEnv* pRuntimeEnv = &pQInfo->runtimeEnv;
   SQuery* pQuery = pQInfo->runtimeEnv.pQuery;
   int32_t step = GET_FORWARD_DIRECTION_FACTOR(pQuery->order.order);
 
-  if (!QUERY_IS_INTERVAL_QUERY(pQuery)) {
-    setExecutionContext(pQInfo, pTableQueryInfo->groupIndex, pBlockInfo->window.ekey + step);
-  } else {  // interval query
+  if (QUERY_IS_INTERVAL_QUERY(pQuery)) {
     TSKEY nextKey = pBlockInfo->window.skey;
     setIntervalQueryRange(pQInfo, nextKey);
 
     if (pRuntimeEnv->hasTagResults || pRuntimeEnv->pTsBuf != NULL) {
       setAdditionalInfo(pQInfo, pTableQueryInfo->pTable, pTableQueryInfo);
     }
+  } else {  // non-interval query
+    setExecutionContext(pQInfo, pTableQueryInfo->groupIndex, pBlockInfo->window.ekey + step);
   }
 }
 
@@ -5626,8 +5631,6 @@ static void tableAggregationProcess(SQInfo *pQInfo, STableQueryInfo* pTableInfo)
     return;
   }
 
-  pQuery->current = pTableInfo;  // set current query table info
-
   scanOneTableDataBlocks(pRuntimeEnv, pTableInfo->lastKey);
   finalizeQueryResult(pRuntimeEnv);
 
@@ -5646,10 +5649,8 @@ static void tableAggregationProcess(SQInfo *pQInfo, STableQueryInfo* pTableInfo)
 static void tableProjectionProcess(SQInfo *pQInfo, STableQueryInfo* pTableInfo) {
   SQueryRuntimeEnv *pRuntimeEnv = &pQInfo->runtimeEnv;
 
-  SQuery *pQuery = pRuntimeEnv->pQuery;
-  pQuery->current = pTableInfo;
-
   // for ts_comp query, re-initialized is not allowed
+  SQuery *pQuery = pRuntimeEnv->pQuery;
   if (!isTSCompQuery(pQuery)) {
     resetDefaultResInfoOutputBuf(pRuntimeEnv);
   }
@@ -5701,9 +5702,7 @@ static void tableProjectionProcess(SQInfo *pQInfo, STableQueryInfo* pTableInfo)
 // handle time interval query on table
 static void tableIntervalProcess(SQInfo *pQInfo, STableQueryInfo* pTableInfo) {
   SQueryRuntimeEnv *pRuntimeEnv = &(pQInfo->runtimeEnv);
-
   SQuery *pQuery = pRuntimeEnv->pQuery;
-  pQuery->current = pTableInfo;
 
   TSKEY newStartKey = QUERY_IS_ASC_QUERY(pQuery)? INT64_MIN:INT64_MAX;
 
@@ -5773,7 +5772,6 @@ static void tableQueryImpl(SQInfo *pQInfo) {
       }
 
       qDebug("QInfo:%p current:%" PRId64 " returned, total:%" PRId64, pQInfo, pQuery->rec.rows, pQuery->rec.total);
-      return;
     } else {
       pQuery->rec.rows = 0;
       assert(pRuntimeEnv->windowResInfo.size > 0);
@@ -5791,9 +5789,9 @@ static void tableQueryImpl(SQInfo *pQInfo) {
       if (pQuery->rec.rows <= 0 || pRuntimeEnv->windowResInfo.size <= pQInfo->groupIndex) {
         qDebug("QInfo:%p query over, %" PRId64 " rows are returned", pQInfo, pQuery->rec.total);
       }
-
-      return;
     }
+
+    return;
   }
 
   // number of points returned during this query
@@ -5802,7 +5800,9 @@ static void tableQueryImpl(SQInfo *pQInfo) {
 
   assert(pQInfo->tableqinfoGroupInfo.numOfTables == 1);
   SArray* g = GET_TABLEGROUP(pQInfo, 0);
+
   STableQueryInfo* item = taosArrayGetP(g, 0);
+  pQuery->current = item;
 
   // group by normal column, sliding window query, interval query are handled by interval query processor
   if (QUERY_IS_INTERVAL_QUERY(pQuery) || pRuntimeEnv->groupbyColumn) {  // interval (down sampling operation)
@@ -5810,7 +5810,7 @@ static void tableQueryImpl(SQInfo *pQInfo) {
   } else if (isFixedOutputQuery(pRuntimeEnv)) {
     tableAggregationProcess(pQInfo, item);
   } else {  // diff/add/multiply/subtract/division
-    assert(pQuery->checkBuffer == 1);
+    assert(pQuery->checkResultBuf == 1);
     tableProjectionProcess(pQInfo, item);
   }
 
@@ -5830,7 +5830,7 @@ static void stableQueryImpl(SQInfo *pQInfo) {
       (isFixedOutputQuery(pRuntimeEnv) && (!isPointInterpoQuery(pQuery)) && (!pRuntimeEnv->groupbyColumn))) {
     multiTableQueryProcess(pQInfo);
   } else {
-    assert((pQuery->checkBuffer == 1 && pQuery->interval.interval == 0) || isPointInterpoQuery(pQuery) ||
+    assert((pQuery->checkResultBuf == 1 && pQuery->interval.interval == 0) || isPointInterpoQuery(pQuery) ||
            pRuntimeEnv->groupbyColumn);
 
     sequentialTableProcess(pQInfo);

tests/script/general/parser/select_with_tags.sim

@@ -813,8 +813,6 @@ sql_error select first(ts), first(c1),tbname from select_tags_mt0;
 sql_error select first(ts), last(ts), tbname from select_tags_mt0;
 sql_error select last_row(*), first(ts), tbname, t1, t2 from select_tags_mt0;
 sql_error select tbname, last_row(*), t1, first(ts) from select_tags_mt0;
-sql_error select first(ts), tbname from select_tags_tb0;
-sql_error select last_row(*), t1 from select_tags_tb0;
 sql_error select count(*), tbname from select_tags_mt0;
 sql_error select sum(c2), tbname from select_tags_mt0;
 sql_error select avg(c3), tbname from select_tags_mt0;