diff --git a/source/util/src/tcompression.c b/source/util/src/tcompression.c
index a0f5c45df2..75c1997428 100644
--- a/source/util/src/tcompression.c
+++ b/source/util/src/tcompression.c
@@ -1004,12 +1004,12 @@ int32_t tsDecompressDoubleLossyImp(const char *input, int32_t compressedSize, co
 typedef struct {
   int8_t   type;
   int8_t   cmprAlg;
+  int8_t   autoAlloc;
   uint8_t *aBuf[2];
   int64_t  nBuf[2];
   union {
     // Timestamp ----
     struct {
-      int8_t   ts_copy;
       int32_t  ts_n;
       int64_t  ts_prev_val;
       int64_t  ts_prev_delta;
@@ -1051,124 +1051,123 @@ static int32_t tCompSetCopyMode(SCompressor *pCmprsor) {
   int32_t code = 0;
 
   if (pCmprsor->ts_n) {
-    code = tRealloc(&pCmprsor->aBuf[1], sizeof(int64_t) * (pCmprsor->ts_n + 1));
-    if (code) return code;
-    pCmprsor->nBuf[1] = 1;
+    if (pCmprsor->autoAlloc) {
+      code = tRealloc(&pCmprsor->aBuf[1], sizeof(int64_t) * pCmprsor->ts_n);
+      if (code) return code;
+    }
+    pCmprsor->nBuf[1] = 0;
 
     int64_t  n = 1;
-    int64_t  valPrev;
-    int64_t  delPrev;
+    int64_t  value;
+    int64_t  delta;
     uint64_t vZigzag;
     while (n < pCmprsor->nBuf[0]) {
-      uint8_t n1 = pCmprsor->aBuf[0][0] & 0xf;
-      uint8_t n2 = pCmprsor->aBuf[0][0] >> 4;
+      uint8_t aN[2];
+      aN[0] = pCmprsor->aBuf[0][n] & 0xf;
+      aN[1] = pCmprsor->aBuf[0][n] >> 4;
 
       n++;
 
-      vZigzag = 0;
-      for (uint8_t i = 0; i < n1; i++) {
-        vZigzag |= (((uint64_t)pCmprsor->aBuf[0][n]) << (sizeof(int64_t) * i));
-        n++;
-      }
-      int64_t delta_of_delta = ZIGZAG_DECODE(int64_t, vZigzag);
-      if (n == 2) {
-        delPrev = 0;
-        valPrev = delta_of_delta;
-      } else {
-        delPrev = delta_of_delta + delPrev;
-        valPrev = delPrev + valPrev;
-      }
+      for (int32_t i = 0; i < 2; i++) {
+        vZigzag = 0;
+        for (uint8_t j = 0; j < aN[i]; j++) {
+          vZigzag |= (((uint64_t)pCmprsor->aBuf[0][n]) << (8 * j));
+          n++;
+        }
 
-      memcpy(pCmprsor->aBuf[1] + pCmprsor->nBuf[1], &valPrev, sizeof(int64_t));
-      pCmprsor->nBuf[1] += sizeof(int64_t);
+        int64_t delta_of_delta = ZIGZAG_DECODE(int64_t, vZigzag);
+        if (pCmprsor->nBuf[1] == 0) {
+          delta = 0;
+          value = delta_of_delta;
+        } else {
+          delta = delta_of_delta + delta;
+          value = delta + value;
+        }
 
-      if (n >= pCmprsor->nBuf[0]) break;
+        memcpy(pCmprsor->aBuf[1] + pCmprsor->nBuf[1], &value, sizeof(int64_t));
+        pCmprsor->nBuf[1] += sizeof(int64_t);
 
-      vZigzag = 0;
-      for (uint8_t i = 0; i < n2; i++) {
-        vZigzag |= (((uint64_t)pCmprsor->aBuf[0][n]) << (sizeof(int64_t) * i));
-        n++;
+        if (n >= pCmprsor->nBuf[0]) break;
       }
-      delta_of_delta = ZIGZAG_DECODE(int64_t, vZigzag);
-      delPrev = delta_of_delta + delPrev;
-      valPrev = delPrev + valPrev;
     }
 
-    uint8_t *pBuf = pCmprsor->aBuf[0];
-    pCmprsor->aBuf[0] = pCmprsor->aBuf[1];
-    pCmprsor->aBuf[1] = pBuf;
-    pCmprsor->nBuf[0] = pCmprsor->nBuf[1];
-  } else {
-    // TODO
-  }
+    ASSERT(n == pCmprsor->nBuf[0]);
 
-  pCmprsor->aBuf[0][0] = 0;
-  pCmprsor->ts_copy = 1;
+    if (pCmprsor->autoAlloc) {
+      code = tRealloc(&pCmprsor->aBuf[0], pCmprsor->nBuf[1] + 1);
+      if (code) return code;
+    }
+    memcpy(pCmprsor->aBuf[0] + 1, pCmprsor->aBuf[1], pCmprsor->nBuf[1]);
+    pCmprsor->nBuf[0] = 1 + pCmprsor->nBuf[1];
+  }
+  pCmprsor->aBuf[0][0] = MODE_NOCOMPRESS;
 
   return code;
 }
-static int32_t tCompTimestamp(SCompressor *pCmprsor, TSKEY ts) {
+static int32_t tCompTimestamp(SCompressor *pCmprsor, int64_t ts) {
   int32_t code = 0;
 
-  if (pCmprsor->ts_n == 0) {
+  ASSERT(pCmprsor->type == TSDB_DATA_TYPE_TIMESTAMP);
+
+  if (pCmprsor->aBuf[0][0] == MODE_COMPRESS) {
+    if (pCmprsor->ts_n == 0) {
+      pCmprsor->ts_prev_val = ts;
+      pCmprsor->ts_prev_delta = -ts;
+    }
+
+    if (!I64_SAFE_ADD(ts, -pCmprsor->ts_prev_val)) {
+      code = tCompSetCopyMode(pCmprsor);
+      if (code) return code;
+      goto _copy_cmpr;
+    }
+    int64_t delta = ts - pCmprsor->ts_prev_val;
+
+    if (!I64_SAFE_ADD(delta, -pCmprsor->ts_prev_delta)) {
+      code = tCompSetCopyMode(pCmprsor);
+      if (code) return code;
+      goto _copy_cmpr;
+    }
+    int64_t  delta_of_delta = delta - pCmprsor->ts_prev_delta;
+    uint64_t vZigzag = ZIGZAG_ENCODE(int64_t, delta_of_delta);
+
     pCmprsor->ts_prev_val = ts;
-    pCmprsor->ts_prev_delta = -ts;
-  }
+    pCmprsor->ts_prev_delta = delta;
 
-  if (pCmprsor->ts_copy) goto _copy_exit;
+    if ((pCmprsor->ts_n & 0x1) == 0) {
+      if (pCmprsor->autoAlloc) {
+        code = tRealloc(&pCmprsor->aBuf[0], pCmprsor->nBuf[0] + 17);
+        if (code) return code;
+      }
 
-  if (!I64_SAFE_ADD(ts, -pCmprsor->ts_prev_val)) {
-    code = tCompSetCopyMode(pCmprsor);
-    if (code) return code;
-    goto _copy_exit;
-  }
-
-  int64_t delta = ts - pCmprsor->ts_prev_val;
-
-  if (!I64_SAFE_ADD(delta, -pCmprsor->ts_prev_delta)) {
-    code = tCompSetCopyMode(pCmprsor);
-    if (code) return code;
-    goto _copy_exit;
-  }
-
-  int64_t  delta_of_delta = delta - pCmprsor->ts_prev_delta;
-  uint64_t zigzag_value = ZIGZAG_ENCODE(int64_t, delta_of_delta);
-
-  pCmprsor->ts_prev_val = ts;
-  pCmprsor->ts_prev_delta = delta;
-
-  if (pCmprsor->ts_n & 0x1 == 0) {
-    code = tRealloc(&pCmprsor->aBuf[0], pCmprsor->nBuf[0] + 17 /*sizeof(int64_t) * 2 + 1*/);
-    if (code) return code;
-
-    pCmprsor->ts_flag_p = &pCmprsor->aBuf[0][pCmprsor->nBuf[0]];
-    pCmprsor->nBuf[0]++;
-    pCmprsor->ts_flag_p[0] = 0;
-
-    while (zigzag_value) {
-      pCmprsor->aBuf[0][pCmprsor->nBuf[0]] = (zigzag_value & 0xff);
+      pCmprsor->ts_flag_p = pCmprsor->aBuf[0] + pCmprsor->nBuf[0];
       pCmprsor->nBuf[0]++;
-      pCmprsor->ts_flag_p[0]++;
+      pCmprsor->ts_flag_p[0] = 0;
+      while (vZigzag) {
+        pCmprsor->aBuf[0][pCmprsor->nBuf[0]] = (vZigzag & 0xff);
+        pCmprsor->nBuf[0]++;
+        pCmprsor->ts_flag_p[0]++;
+        vZigzag >>= 8;
+      }
+    } else {
+      while (vZigzag) {
+        pCmprsor->aBuf[0][pCmprsor->nBuf[0]] = (vZigzag & 0xff);
+        pCmprsor->nBuf[0]++;
+        pCmprsor->ts_flag_p[0] += 0x10;
+        vZigzag >>= 8;
+      }
     }
   } else {
-    while (zigzag_value) {
-      pCmprsor->aBuf[0][pCmprsor->nBuf[0]] = (zigzag_value & 0xff);
-      pCmprsor->nBuf[0]++;
-      pCmprsor->ts_flag_p += (uint8_t)0x10;
+  _copy_cmpr:
+    if (pCmprsor->autoAlloc) {
+      code = tRealloc(&pCmprsor->aBuf[0], pCmprsor->nBuf[0] + sizeof(ts));
+      if (code) return code;
     }
+
+    memcpy(pCmprsor->aBuf[0] + pCmprsor->nBuf[0], &ts, sizeof(ts));
+    pCmprsor->nBuf[0] += sizeof(ts);
   }
-
   pCmprsor->ts_n++;
-  return code;
 
-_copy_exit:
-  code = tRealloc(&pCmprsor->aBuf[0], pCmprsor->nBuf[0] + sizeof(int64_t));
-  if (code) return code;
-
-  memcpy(pCmprsor->aBuf[0] + pCmprsor->nBuf[0], &ts, sizeof(ts));
-  pCmprsor->nBuf[0] += sizeof(ts);
-
-  pCmprsor->ts_n++;
   return code;
 }
 
@@ -1432,17 +1431,22 @@ int32_t tCompressorDestroy(SCompressor *pCmprsor) {
   return code;
 }
 
-int32_t tCompressorReset(SCompressor *pCmprsor, int8_t type, int8_t cmprAlg) {
+int32_t tCompressorReset(SCompressor *pCmprsor, int8_t type, int8_t cmprAlg, int8_t autoAlloc) {
   int32_t code = 0;
 
   pCmprsor->type = type;
   pCmprsor->cmprAlg = cmprAlg;
-  pCmprsor->nBuf[0] = 0;  // (todo) may or may not +/- 1
+  pCmprsor->autoAlloc = autoAlloc;
 
   switch (type) {
     case TSDB_DATA_TYPE_TIMESTAMP:
-      pCmprsor->ts_copy = 0;
       pCmprsor->ts_n = 0;
+      pCmprsor->ts_prev_val = 0;
+      pCmprsor->ts_prev_delta = 0;
+      pCmprsor->ts_flag_p = NULL;
+      pCmprsor->aBuf[0][0] = MODE_COMPRESS;
+      pCmprsor->nBuf[0] = 1;
+      pCmprsor->nBuf[1] = 0;
       break;
     case TSDB_DATA_TYPE_BOOL:
       pCmprsor->bool_n = 0;