diff --git a/src/client/src/tscLocal.c b/src/client/src/tscLocal.c
index 946cc0679348258e7134b0e4fa476c18df265aa7..3dfac55adbc33823f8bf0a3a0b51c9abe594fae9 100644
--- a/src/client/src/tscLocal.c
+++ b/src/client/src/tscLocal.c
@@ -131,17 +131,23 @@ static int32_t tscSetValueToResObj(SSqlObj *pSql, int32_t rowLen) {
 
   for (int32_t i = 0; i < numOfRows; ++i) {
     TAOS_FIELD *pField = tscFieldInfoGetField(&pQueryInfo->fieldsInfo, 0);
-    strncpy(pRes->data + tscFieldInfoGetOffset(pQueryInfo, 0) * totalNumOfRows + pField->bytes * i, pSchema[i].name,
-            TSDB_COL_NAME_LEN);
+    char* dst = pRes->data + tscFieldInfoGetOffset(pQueryInfo, 0) * totalNumOfRows + pField->bytes * i;
+    STR_TO_VARSTR(dst, pSchema[i].name);
 
     char *type = tDataTypeDesc[pSchema[i].type].aName;
 
     pField = tscFieldInfoGetField(&pQueryInfo->fieldsInfo, 1);
-    strncpy(pRes->data + tscFieldInfoGetOffset(pQueryInfo, 1) * totalNumOfRows + pField->bytes * i, type, pField->bytes);
-
+    dst = pRes->data + tscFieldInfoGetOffset(pQueryInfo, 1) * totalNumOfRows + pField->bytes * i;
+    
+    STR_TO_VARSTR(dst, type);
+    
     int32_t bytes = pSchema[i].bytes;
-    if (pSchema[i].type == TSDB_DATA_TYPE_NCHAR) {
-      bytes = bytes / TSDB_NCHAR_SIZE;
+    if (pSchema[i].type == TSDB_DATA_TYPE_BINARY || pSchema[i].type == TSDB_DATA_TYPE_NCHAR) {
+      bytes -= VARSTR_HEADER_SIZE;
+      
+      if (pSchema[i].type == TSDB_DATA_TYPE_NCHAR) {
+        bytes = bytes / TSDB_NCHAR_SIZE;
+      }
     }
 
     pField = tscFieldInfoGetField(&pQueryInfo->fieldsInfo, 2);
@@ -233,7 +239,7 @@ static int32_t tscSetValueToResObj(SSqlObj *pSql, int32_t rowLen) {
   return 0;
 }
 
-static int32_t tscBuildMeterSchemaResultFields(SSqlObj *pSql, int32_t numOfCols, int32_t typeColLength,
+static int32_t tscBuildTableSchemaResultFields(SSqlObj *pSql, int32_t numOfCols, int32_t typeColLength,
                                                int32_t noteColLength) {
   int32_t  rowLen = 0;
   SColumnIndex index = {0};
@@ -243,14 +249,14 @@ static int32_t tscBuildMeterSchemaResultFields(SSqlObj *pSql, int32_t numOfCols,
   SQueryInfo* pQueryInfo = tscGetQueryInfoDetail(&pSql->cmd, 0);
   pQueryInfo->order.order = TSDB_ORDER_ASC;
 
-  TAOS_FIELD f = {.type = TSDB_DATA_TYPE_BINARY, .bytes = TSDB_COL_NAME_LEN};
+  TAOS_FIELD f = {.type = TSDB_DATA_TYPE_BINARY, .bytes = TSDB_COL_NAME_LEN + VARSTR_HEADER_SIZE};
   strncpy(f.name, "Field", TSDB_COL_NAME_LEN);
   
   SFieldSupInfo* pInfo = tscFieldInfoAppend(&pQueryInfo->fieldsInfo, &f);
-  pInfo->pSqlExpr = tscSqlExprAppend(pQueryInfo, TSDB_FUNC_TS_DUMMY, &index, TSDB_DATA_TYPE_BINARY, TSDB_COL_NAME_LEN,
-      TSDB_COL_NAME_LEN, false);
+  pInfo->pSqlExpr = tscSqlExprAppend(pQueryInfo, TSDB_FUNC_TS_DUMMY, &index, TSDB_DATA_TYPE_BINARY,
+      TSDB_COL_NAME_LEN + VARSTR_HEADER_SIZE, TSDB_COL_NAME_LEN, false);
   
-  rowLen += TSDB_COL_NAME_LEN;
+  rowLen += (TSDB_COL_NAME_LEN + VARSTR_HEADER_SIZE);
 
   f.bytes = typeColLength;
   f.type = TSDB_DATA_TYPE_BINARY;
@@ -289,17 +295,16 @@ static int32_t tscProcessDescribeTable(SSqlObj *pSql) {
   
   assert(tscGetMetaInfo(pQueryInfo, 0)->pTableMeta != NULL);
 
-  const int32_t NUM_OF_DESCRIBE_TABLE_COLUMNS = 4;
+  const int32_t NUM_OF_DESC_TABLE_COLUMNS = 4;
   const int32_t TYPE_COLUMN_LENGTH = 16;
   const int32_t NOTE_COLUMN_MIN_LENGTH = 8;
 
-  int32_t note_field_length = tscMaxLengthOfTagsFields(pSql);
-  if (note_field_length == 0) {
-    note_field_length = NOTE_COLUMN_MIN_LENGTH;
+  int32_t noteFieldLen = tscMaxLengthOfTagsFields(pSql);
+  if (noteFieldLen == 0) {
+    noteFieldLen = NOTE_COLUMN_MIN_LENGTH;
   }
 
-  int32_t rowLen =
-      tscBuildMeterSchemaResultFields(pSql, NUM_OF_DESCRIBE_TABLE_COLUMNS, TYPE_COLUMN_LENGTH, note_field_length);
+  int32_t rowLen = tscBuildTableSchemaResultFields(pSql, NUM_OF_DESC_TABLE_COLUMNS, TYPE_COLUMN_LENGTH, noteFieldLen);
   tscFieldInfoUpdateOffset(pQueryInfo);
   return tscSetValueToResObj(pSql, rowLen);
 }
diff --git a/src/common/inc/tdataformat.h b/src/common/inc/tdataformat.h
index 53cf2a1158aa49556cc6363533d473b751745b1e..f3508b6e7fc9a35ecb7934a39b837727c5919dc1 100644
--- a/src/common/inc/tdataformat.h
+++ b/src/common/inc/tdataformat.h
@@ -26,6 +26,17 @@
 extern "C" {
 #endif
 
+#define VARSTR_HEADER_SIZE sizeof(int16_t)
+#define STR_TO_VARSTR(x, str) do {int16_t __len = strlen(str); \
+  *(int16_t*)(x) = __len; \
+  strncpy((char*)(x) + VARSTR_HEADER_SIZE, (str), __len);} while(0);
+  
+#define STR_TO_VARSTR_WITH_SIZE(x, str, _size) do {\
+  int16_t __len = strnlen((str), (_size)); \
+  *(int16_t*)(x) = __len; \
+  strncpy((char*)(x) + VARSTR_HEADER_SIZE, (str), __len);\
+} while(0);
+
 // ----------------- TSDB COLUMN DEFINITION
 typedef struct {
   int8_t  type;    // Column type
diff --git a/src/mnode/src/mgmtDb.c b/src/mnode/src/mgmtDb.c
index 3e7577af0696ef591217224d3e08403f16fd5097..311842083c96889fe8923574371b3cab8e7e2d8e 100644
--- a/src/mnode/src/mgmtDb.c
+++ b/src/mnode/src/mgmtDb.c
@@ -579,7 +579,11 @@ static int32_t mgmtRetrieveDbs(SShowObj *pShow, char *data, int32_t rows, void *
     cols = 0;
 
     pWrite = data + pShow->offset[cols] * rows + pShow->bytes[cols] * numOfRows;
-    strcpy(pWrite, mgmtGetDbStr(pDb->name));
+    char* name = mgmtGetDbStr(pDb->name);
+    *(int16_t*) pWrite = strnlen(name, TSDB_DB_NAME_LEN);
+    pWrite += sizeof(int16_t); // todo refactor
+    
+    strncpy(pWrite, mgmtGetDbStr(pDb->name), TSDB_DB_NAME_LEN);
     cols++;
 
     pWrite = data + pShow->offset[cols] * rows + pShow->bytes[cols] * numOfRows;
diff --git a/src/mnode/src/mgmtTable.c b/src/mnode/src/mgmtTable.c
index ff65ba4e54d1d3082db4b36cc9e91a11ea8fbdad..99d00a144540348cd514dddbc678665d295775a9 100644
--- a/src/mnode/src/mgmtTable.c
+++ b/src/mnode/src/mgmtTable.c
@@ -1119,7 +1119,12 @@ int32_t mgmtRetrieveShowSuperTables(SShowObj *pShow, char *data, int32_t rows, v
     cols = 0;
 
     pWrite = data + pShow->offset[cols] * rows + pShow->bytes[cols] * numOfRows;
-    strncpy(pWrite, stableName, TSDB_TABLE_NAME_LEN);
+  
+    int16_t len = strnlen(stableName, TSDB_DB_NAME_LEN);
+    *(int16_t*) pWrite = len;
+    pWrite += sizeof(int16_t); // todo refactor
+  
+    strncpy(pWrite, stableName, len);
     cols++;
 
     pWrite = data + pShow->offset[cols] * rows + pShow->bytes[cols] * numOfRows;
@@ -2075,7 +2080,12 @@ static int32_t mgmtRetrieveShowTables(SShowObj *pShow, char *data, int32_t rows,
     int32_t cols = 0;
 
     char *pWrite = data + pShow->offset[cols] * rows + pShow->bytes[cols] * numOfRows;
-    strncpy(pWrite, tableName, TSDB_TABLE_NAME_LEN);
+
+    int16_t len = strnlen(tableName, TSDB_DB_NAME_LEN);
+    *(int16_t*) pWrite = len;
+    pWrite += sizeof(int16_t); // todo refactor
+    
+    strncpy(pWrite, tableName, len);
     cols++;
 
     pWrite = data + pShow->offset[cols] * rows + pShow->bytes[cols] * numOfRows;
diff --git a/src/tsdb/src/tsdbRead.c b/src/tsdb/src/tsdbRead.c
index 08432fb1c87f4705e008298d08d39f720a89bbb0..ff521a419409ef97cb8f0f9bb2a973e5085ea15a 100644
--- a/src/tsdb/src/tsdbRead.c
+++ b/src/tsdb/src/tsdbRead.c
@@ -415,16 +415,11 @@ static bool doLoadFileDataBlock(STsdbQueryHandle* pQueryHandle, SCompBlock* pBlo
   SArray* sa = getDefaultLoadColumns(pQueryHandle, true);
 
   if (pCheckInfo->pDataCols == NULL) {
-    pCheckInfo->pDataCols = tdNewDataCols(1000, 2, 4096);
+    pCheckInfo->pDataCols = tdNewDataCols(1000, 100, 4096);  //todo fix me
   }
 
   tdInitDataCols(pCheckInfo->pDataCols, tsdbGetTableSchema(tsdbGetMeta(pQueryHandle->pTsdb), pCheckInfo->pTableObj));
 
-  // SFile* pFile = &pQueryHandle->pFileGroup->files[TSDB_FILE_TYPE_DATA];
-  // if (pFile->fd == FD_INITIALIZER) {
-  //   pFile->fd = open(pFile->fname, O_RDONLY);
-  // }
-
   if (tsdbLoadBlockData(&(pQueryHandle->rhelper), pBlock, NULL) == 0) {
     SDataBlockLoadInfo* pBlockLoadInfo = &pQueryHandle->dataBlockLoadInfo;
 
@@ -601,27 +596,27 @@ static void filterDataInDataBlock(STsdbQueryHandle* pQueryHandle, STableCheckInf
 //  }
 
   // move the data block in the front to data block if needed
-  int32_t numOfCols = QH_GET_NUM_OF_COLS(pQueryHandle);
-
-  for (int32_t i = 0; i < taosArrayGetSize(sa); ++i) {
-    int16_t colId = *(int16_t*)taosArrayGet(sa, i);
+  int32_t numOfCols = pQueryHandle->rhelper.pDataCols[0]->numOfCols;
+  int32_t reqCols = taosArrayGetSize(pQueryHandle->pColumns);
+  
+  for (int32_t i = 0; i < reqCols; ++i) {
+//    int16_t colId = *(int16_t*)taosArrayGet(sa, i);
+    SColumnInfoData* pCol = taosArrayGet(pQueryHandle->pColumns, i);
+    int32_t bytes = pCol->info.bytes;
 
     for (int32_t j = 0; j < numOfCols; ++j) {
-      SColumnInfoData* pCol = taosArrayGet(pQueryHandle->pColumns, j);
-      int32_t bytes = pCol->info.bytes;
+      SDataCol* src = &pQueryHandle->rhelper.pDataCols[0]->cols[j];
 
-      if (pCol->info.colId == colId) {
+      if (pCol->info.colId == src->colId) {
         if (pCol->info.type != TSDB_DATA_TYPE_BINARY && pCol->info.type != TSDB_DATA_TYPE_NCHAR) {
-          memmove(pCol->pData, pQueryHandle->rhelper.pDataCols[0]->cols[i].pData + bytes * start,
-                       bytes * pQueryHandle->realNumOfRows);
-        } else {
-          SDataCol* src = &pQueryHandle->rhelper.pDataCols[0]->cols[i];
-          
+          memmove(pCol->pData, src->pData + bytes * start, bytes * pQueryHandle->realNumOfRows);
+        } else { // handle the var-string
           for(int32_t k = start; k < pQueryHandle->realNumOfRows + start; ++k) {
             char* p = tdGetColDataOfRow(src, k);
-            memcpy(pCol->pData + k * bytes, p, *(int16_t*) p + sizeof(int16_t));  // todo refactor
+            memcpy(pCol->pData + k * bytes, p, varDataTLen(p));  // todo refactor
           }
         }
+        
         break;
       }
     }
@@ -1010,7 +1005,7 @@ void changeQueryHandleForQuery(TsdbQueryHandleT pqHandle) {
   pQueryHandle->window = (STimeWindow) {key, key};
 }
 
-static int tsdbReadRowsFromCache(SSkipListIterator* pIter, TSKEY maxKey, int maxRowsToRead, TSKEY* skey, TSKEY* ekey,
+static int tsdbReadRowsFromCache(SSkipListIterator* pIter, STable* pTable, TSKEY maxKey, int maxRowsToRead, TSKEY* skey, TSKEY* ekey,
                                  STsdbQueryHandle* pQueryHandle) {
   int     numOfRows = 0;
   int32_t numOfCols = taosArrayGetSize(pQueryHandle->pColumns);
@@ -1040,8 +1035,11 @@ static int tsdbReadRowsFromCache(SSkipListIterator* pIter, TSKEY maxKey, int max
 
     *ekey = dataRowKey(row);
 
-    int32_t offset = 0;
+    int32_t offset = -1;
     char* pData = NULL;
+  
+    STSchema* pSchema = tsdbGetTableSchema(tsdbGetMeta(pQueryHandle->pTsdb), pTable);
+    int32_t numOfTableCols = schemaNCols(pSchema);
     
     for (int32_t i = 0; i < numOfCols; ++i) {
       SColumnInfoData* pColInfo = taosArrayGet(pQueryHandle->pColumns, i);
@@ -1052,6 +1050,15 @@ static int tsdbReadRowsFromCache(SSkipListIterator* pIter, TSKEY maxKey, int max
         pData = pColInfo->pData + (maxRowsToRead - numOfRows - 1) * pColInfo->info.bytes;
       }
       
+      for(int32_t j = 0; j < numOfTableCols; ++j) {
+        if (pColInfo->info.colId == pSchema->columns[j].colId) {
+          offset = pSchema->columns[j].offset;
+          break;
+        }
+      }
+      
+      assert(offset != -1); // todo handle error
+      
       if (pColInfo->info.type == TSDB_DATA_TYPE_BINARY || pColInfo->info.type == TSDB_DATA_TYPE_NCHAR) {
         void *value = tdGetRowDataOfCol(row, pColInfo->info.type, TD_DATA_ROW_HEAD_SIZE + offset);
         memcpy(pData, value, varDataTLen(value));
@@ -1127,7 +1134,7 @@ SDataBlockInfo tsdbRetrieveDataBlockInfo(TsdbQueryHandleT* pQueryHandle) {
     if (pTable->mem != NULL) {
       // create mem table iterator if it is not created yet
       assert(pCheckInfo->iter != NULL);
-      rows = tsdbReadRowsFromCache(pCheckInfo->iter, pHandle->window.ekey, 4000, &skey, &ekey, pHandle);
+      rows = tsdbReadRowsFromCache(pCheckInfo->iter, pCheckInfo->pTableObj, pHandle->window.ekey, 4000, &skey, &ekey, pHandle);
 
       // update the last key value
       pCheckInfo->lastKey = ekey + step;
diff --git a/tests/examples/c/demo.c b/tests/examples/c/demo.c
index cfeb5c8eb768a8688082231dd3b647228dc5ab28..a2073b09b32a922cd097369b912a4fbddbec5e93 100644
--- a/tests/examples/c/demo.c
+++ b/tests/examples/c/demo.c
@@ -75,11 +75,13 @@ int main(int argc, char *argv[]) {
   
   doQuery(taos, "create database if not exists test");
   doQuery(taos, "use test");
+  doQuery(taos, "select * from t1 order by ts desc");
+  
 //  doQuery(taos, "create table t1(ts timestamp, k binary(12), f nchar(2))");
-  for(int32_t i = 0; i< 100000; ++i) {
-    doQuery(taos, "select m1.ts,m1.a from m1, m2 where m1.ts=m2.ts and m1.a=m2.b;");
-    usleep(500000);
-  }
+//  for(int32_t i = 0; i< 100000; ++i) {
+//    doQuery(taos, "select m1.ts,m1.a from m1, m2 where m1.ts=m2.ts and m1.a=m2.b;");
+//    usleep(500000);
+//  }
 
 //  doQuery(taos, "insert into tm0 values('2020-1-1 1:1:1', 'abc')");
 //  doQuery(taos, "create table if not exists tm0 (ts timestamp, k int);");