diff --git a/src/common/inc/dataformat.h b/src/common/inc/dataformat.h
index 1f46c68abcffa57c246c561b4c64b931d3d5c7ea..207ff4dbfd1aa1f34b32ef93b7f819651d07f7c8 100644
--- a/src/common/inc/dataformat.h
+++ b/src/common/inc/dataformat.h
@@ -105,11 +105,25 @@ SDataRow tdDataRowDup(SDataRow row);
 
 // ----------------- Data column structure
 typedef struct SDataCol {
-  int64_t len;
-  char    data[];
+  int32_t len;
+  void *  pData;
 } SDataCol;
 
-void tdConvertDataRowToCol(SDataCol *cols, STSchema *pSchema, int *iter);
+typedef struct {
+  TSKEY    firstKey;
+  TSKEY    lastKey;
+  int      numOfPoints;
+  int      numOfCols;
+  void *   buf;
+  SDataCol cols[];
+} SDataCols;
+
+#define keyCol(cols) (&((cols)->cols[0])) // Key column
+
+SDataCols *tdNewDataCols(STSchema *pSchema, int nRows);
+void       tdFreeDataCols(SDataCols *pCols);
+void       tdResetDataCols(SDataCols *pCols);
+void       tdAppendDataRowToDataCol(SDataRow row, SDataCols *pCols, STSchema *pSchema);
 
 #ifdef __cplusplus
 }
diff --git a/src/common/src/dataformat.c b/src/common/src/dataformat.c
index 04826e43ac98852495b5951aaa0ba66315bf2480..3c692f9eba8e3528b8238f729051210c24e2d055 100644
--- a/src/common/src/dataformat.c
+++ b/src/common/src/dataformat.c
@@ -294,14 +294,55 @@ SDataRow tdDataRowDup(SDataRow row) {
   return trow;
 }
 
-void tdConvertDataRowToCol(SDataCol *cols, STSchema *pSchema, int *iter) {
-  int row = *iter;
+SDataCols *tdNewDataCols(STSchema *pSchema, int nRows) {
+  int nCols = schemaNCols(pSchema);
+
+  SDataCols *pInfo = (SDataCols *)calloc(1, sizeof(SDataCols) + sizeof(SDataCol) * nCols);
+  if (pInfo == NULL) return NULL;
+
+  pInfo->numOfCols = nCols;
+  pInfo->firstKey = INT64_MIN;
+  pInfo->lastKey = INT64_MAX;
+  pInfo->buf = malloc(tdMaxRowBytesFromSchema(pSchema) * nRows);
+  if (pInfo->buf == NULL) {
+    free(pInfo);
+    return NULL;
+  }
 
-  for (int i = 0; i < schemaNCols(pSchema); i++) {
-    // TODO
+  pInfo->cols[0].pData = pInfo->buf;
+  for (int i = 1; i < nCols; i++) {
+    pInfo->cols[i].pData = (char *)(pInfo->cols[i - 1].pData) + schemaColAt(pSchema, i - 1)->bytes * nRows;
   }
 
-  *iter = row + 1;
+  return pInfo;
+}
+
+void tdFreeDataCols(SDataCols *pCols) {
+  if (pCols) {
+    if (pCols->buf) free(pCols->buf);
+    free(pCols);
+  }
+}
+
+void tdResetDataCols(SDataCols *pCols) {
+  pCols->firstKey = INT64_MAX;
+  pCols->lastKey = INT64_MIN;
+  pCols->numOfPoints = 0;
+  for (int i = 0; i < pCols->numOfCols; i++) {
+    pCols->cols[i].len = 0;
+  }
+}
+
+void tdAppendDataRowToDataCol(SDataRow row, SDataCols *pCols, STSchema *pSchema) {
+  TSKEY key = dataRowKey(row);
+  if (pCols->numOfPoints == 0) pCols->firstKey = key;
+  pCols->lastKey = key;
+  for (int i = 0; i < pCols->numOfCols; i++) {
+    SDataCol *pCol = pCols->cols + i;
+    memcpy((void *)((char *)(pCol->pData) + pCol->len), dataRowAt(row, colOffset(schemaColAt(pSchema, i))),
+           colBytes(schemaColAt(pSchema, i)));
+    pCol->len += colBytes(schemaColAt(pSchema, i));
+  }
 }
 
 /**
diff --git a/src/vnode/tsdb/src/tsdbMain.c b/src/vnode/tsdb/src/tsdbMain.c
index af3a923d904d62c5fc3af8d8f4ca8dfad64c7282..7b1836378d18ffb7cc538bb3fd251c100992a893 100644
--- a/src/vnode/tsdb/src/tsdbMain.c
+++ b/src/vnode/tsdb/src/tsdbMain.c
@@ -84,7 +84,7 @@ static int     tsdbOpenMetaFile(char *tsdbDir);
 static int32_t tsdbInsertDataToTable(tsdb_repo_t *repo, SSubmitBlk *pBlock);
 static int32_t tsdbRestoreCfg(STsdbRepo *pRepo, STsdbCfg *pCfg);
 static int32_t tsdbGetDataDirName(STsdbRepo *pRepo, char *fname);
-static void *  tsdbCommitToFile(void *arg);
+static void *  tsdbCommitData(void *arg);
 
 #define TSDB_GET_TABLE_BY_ID(pRepo, sid) (((STSDBRepo *)pRepo)->pTableList)[sid]
 #define TSDB_GET_TABLE_BY_NAME(pRepo, name)
@@ -327,7 +327,7 @@ int32_t tsdbTriggerCommit(tsdb_repo_t *repo) {
   pRepo->tsdbCache->curBlock = NULL;
 
   // TODO: here should set as detached or use join for memory leak
-  pthread_create(&(pRepo->commitThread), NULL, tsdbCommitToFile, (void *)repo);
+  pthread_create(&(pRepo->commitThread), NULL, tsdbCommitData, (void *)repo);
   tsdbUnLockRepo(repo);
 
   return 0;
@@ -816,7 +816,7 @@ static SSkipListIterator **tsdbCreateTableIters(STsdbMeta *pMeta, int maxTables)
 }
 
 // Commit to file
-static void *tsdbCommitToFile(void *arg) {
+static void *tsdbCommitData(void *arg) {
   // TODO
   printf("Starting to commit....\n");
   STsdbRepo * pRepo = (STsdbRepo *)arg;
@@ -894,4 +894,26 @@ static void *tsdbCommitToFile(void *arg) {
   tsdbUnLockRepo(arg);
 
   return NULL;
+}
+
+static int tsdbCommitToFile(STsdbRepo *pRepo, SSkipListIterator **iters, int fid) {
+  STsdbMeta * pMeta = pRepo->tsdbMeta;
+  STsdbFileH *pFileH = pRepo->tsdbFileH;
+  STsdbCfg *  pCfg = &pRepo->config;
+  TSKEY minKey = 0, maxKey = 0;
+  tsdbGetKeyRangeOfFileId(pCfg->daysPerFile, pCfg->precision, fid, &minKey, &maxKey);
+
+  for (int tid = 0; tid < pCfg->maxTables; tid++) {
+    STable *pTable = pMeta->tables[tid];
+    SSkipListIterator *pIter = iters[tid];
+
+    if (pIter == NULL) continue;
+
+    // Read data
+    // while () {
+
+    // }
+  }
+
+  return 0;
 }
\ No newline at end of file