diff --git a/src/common/inc/dataformat.h b/src/common/inc/dataformat.h
index a7016061e4e5af4afeef6182baafe62c687d7b2d..4e8afd4f0eec26b42842fd4b4ddfcff05d876a13 100644
--- a/src/common/inc/dataformat.h
+++ b/src/common/inc/dataformat.h
@@ -119,13 +119,15 @@ typedef struct {
   int      maxPoints;  // max number of points
   int      numOfPoints;
   int      numOfCols;  // Total number of cols
+  int      sversion;   // TODO: set sversion
   void *   buf;
   SDataCol cols[];
 } SDataCols;
 
 #define keyCol(pCols) (&((pCols)->cols[0]))  // Key column
-#define dataColsKeyFirst(pCols) ((int64_t *)(keyCol(pCols)->pData))[0]
-#define dataColsKeyLast(pCols) ((int64_t *)(keyCol(pCols)->pData))[(pCols)->numOfPoints - 1]
+#define dataColsKeyAt(pCols, idx) ((int64_t *)(keyCol(pCols)->pData))[(idx)]
+#define dataColsKeyFirst(pCols) dataColsKeyAt(pCols, 0)
+#define dataColsKeyLast(pCols) dataColsKeyAt(pCols, (pCols)->numOfPoints - 1)
 
 SDataCols *tdNewDataCols(int maxRowSize, int maxCols, int maxRows);
 void       tdResetDataCols(SDataCols *pCols);
diff --git a/src/vnode/tsdb/inc/tsdbFile.h b/src/vnode/tsdb/inc/tsdbFile.h
index 0f654ad0bde2bf5d2656761b8b2775f18c028dc2..7e358cc0a2479ddfeec9f5cf8aae1f29dee5be19 100644
--- a/src/vnode/tsdb/inc/tsdbFile.h
+++ b/src/vnode/tsdb/inc/tsdbFile.h
@@ -26,6 +26,7 @@ extern "C" {
 #endif
 
 #define TSDB_FILE_HEAD_SIZE 512
+#define TSDB_FILE_DELIMITER 0xF00AFA0F
 
 #define tsdbGetKeyFileId(key, daysPerFile, precision) ((key) / tsMsPerDay[(precision)] / (daysPerFile))
 #define tsdbGetMaxNumOfFiles(keep, daysPerFile) ((keep) / (daysPerFile) + 3)
diff --git a/src/vnode/tsdb/src/tsdbFile.c b/src/vnode/tsdb/src/tsdbFile.c
index 088a164933865382ae33e1b15518818c6d385e27..9a0db96bd0a4b93b410abe95ef6e4438128fbe4e 100644
--- a/src/vnode/tsdb/src/tsdbFile.c
+++ b/src/vnode/tsdb/src/tsdbFile.c
@@ -24,8 +24,6 @@
 
 #include "tsdbFile.h"
 
-#define TSDB_FILE_DELIMITER 0xF00AFA0F
-
 const char *tsdbFileSuffix[] = {
     ".head",  // TSDB_FILE_TYPE_HEAD
     ".data",  // TSDB_FILE_TYPE_DATA
diff --git a/src/vnode/tsdb/src/tsdbMain.c b/src/vnode/tsdb/src/tsdbMain.c
index 5f7dd2513f312bbb5907bac4df8f700a6cfbe789..d18e766c38960b07669f6a66daac408e524c770a 100644
--- a/src/vnode/tsdb/src/tsdbMain.c
+++ b/src/vnode/tsdb/src/tsdbMain.c
@@ -1041,13 +1041,70 @@ static int tsdbHasDataToCommit(SSkipListIterator **iters, int nIters, TSKEY minK
   return 0;
 }
 
+static int tsdbWriteBlockToFileImpl(SFile *pFile, SDataCols *pCols, int pointsToWrite, int64_t *offset, int32_t *len, int64_t uid) {
+  size_t     size = sizeof(SCompData) + sizeof(SCompCol) * pCols->numOfCols;
+  SCompData *pCompData = (SCompData *)malloc(size);
+  if (pCompData == NULL) return -1;
+
+  pCompData->delimiter = TSDB_FILE_DELIMITER;
+  pCompData->uid = uid;
+  pCompData->numOfCols = pCols->numOfCols;
+
+  *offset = lseek(pFile->fd, 0, SEEK_END);
+  *len = size;
+
+  int toffset = size;
+  for (int iCol = 0; iCol < pCols->numOfCols; iCol++) {
+    SCompCol *pCompCol = pCompData->cols + iCol;
+    SDataCol *pDataCol = pCols->cols + iCol;
+    
+    pCompCol->colId = pDataCol->colId;
+    pCompCol->type = pDataCol->type;
+    pCompCol->offset = toffset;
+
+    // TODO: add compression
+    pCompCol->len = TYPE_BYTES[pCompCol->type] * pointsToWrite;
+    toffset += pCompCol->len;
+  }
+
+  // Write the block
+  if (write(pFile->fd, (void *)pCompData, size) < 0) goto _err;
+  for (int iCol = 0; iCol < pCols->numOfCols; iCol++) {
+    SDataCol *pDataCol = pCols->cols + iCol;
+    SCompCol *pCompCol = pCompData->cols + iCol;
+    if (write(pFile->fd, pDataCol->pData, pCompCol->len) < 0) goto _err;
+  }
+
+  if (pCompData == NULL) free((void *)pCompData);
+  return 0;
+
+_err:
+  if (pCompData == NULL) free((void *)pCompData);
+  return -1;
+}
+
 static int tsdbWriteBlockToFile(STsdbRepo *pRepo, SCompIdx *pIdx, SCompInfo *pCompInfo, SDataCols *pCols, SCompBlock *pCompBlock) {
   STsdbCfg *pCfg = &(pRepo->config);
+  SCompData *pCompData = NULL;
 
   memset((void *)pCompBlock, 0, sizeof(SCompBlock));
 
   if (pCompInfo == NULL) {
-    // Just need to append to file
+    if (pCols->numOfPoints > pCfg->minRowsPerFileBlock) { // Write to .data file
+      // tsdbWriteBlockToFileImpl()
+    } else { // Write to .last or .l file
+      pCompBlock->last = 1;
+
+    }
+    // pCompBlock->offset = ;
+    // pCompBlock->len = ;
+    pCompBlock->algorithm = 2; // TODO : add to configuration
+    pCompBlock->sversion = pCols->sversion;
+    pCompBlock->numOfPoints = pCols->numOfPoints;
+    pCompBlock->numOfSubBlocks = 1;
+    pCompBlock->numOfCols = pCols->numOfCols;
+    pCompBlock->keyFirst = dataColsKeyFirst(pCols);
+    pCompBlock->keyLast = dataColsKeyLast(pCols);
   } else {
     // Need to merge
   }