diff --git a/source/libs/index/inc/indexInt.h b/source/libs/index/inc/indexInt.h
index 742427bf94d3e76f94802d1c19a032c80912f5b9..a6862c05c89aac6aa81c111c68df9b64a1673516 100644
--- a/source/libs/index/inc/indexInt.h
+++ b/source/libs/index/inc/indexInt.h
@@ -17,6 +17,7 @@
 #define _TD_INDEX_INT_H_
 
 #include "index.h"
+#include "tlog.h"
 
 #ifdef USE_LUCENE
 #include <lucene++/Lucene_c.h>
@@ -60,6 +61,16 @@ typedef struct SIndexTermQuery {
 
 SIndexTerm *indexTermCreate(const char *key, int32_t nKey, const char *val, int32_t nVal);
 void        indexTermDestroy(SIndexTerm *p);
+
+
+#define indexFatal(...) do { if (sDebugFlag & DEBUG_FATAL) { taosPrintLog("index FATAL ", 255, __VA_ARGS__); }}     while(0)
+#define indexError(...) do { if (sDebugFlag & DEBUG_ERROR) { taosPrintLog("index ERROR ", 255, __VA_ARGS__); }}     while(0)
+#define indexWarn(...)  do { if (sDebugFlag & DEBUG_WARN)  { taosPrintLog("index WARN ", 255, __VA_ARGS__); }}      while(0)
+#define indexInfo(...)  do { if (sDebugFlag & DEBUG_INFO)  { taosPrintLog("index ", 255, __VA_ARGS__); }}           while(0)
+#define indexDebug(...) do { if (sDebugFlag & DEBUG_DEBUG) { taosPrintLog("index ", sDebugFlag, __VA_ARGS__); }} while(0)
+#define indexTrace(...) do { if (sDebugFlag & DEBUG_TRACE) { taosPrintLog("index ", sDebugFlag, __VA_ARGS__); }} while(0)
+
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/source/libs/index/inc/index_fst_counting_writer.h b/source/libs/index/inc/index_fst_counting_writer.h
index 9280461780fc5aeaeace7339ff114849432bf695..ea090389bba1ff1a12b91ebcac2d15827916286a 100644
--- a/source/libs/index/inc/index_fst_counting_writer.h
+++ b/source/libs/index/inc/index_fst_counting_writer.h
@@ -25,7 +25,7 @@ extern "C" {
 
 #define DefaultMem  1024*1024
 
-static char tmpFile[] = "/tmp/index";
+static char tmpFile[] = "./index";
 typedef enum WriterType {TMemory, TFile} WriterType;   
 
 typedef struct WriterCtx {
@@ -45,7 +45,7 @@ static int writeCtxDoWrite(WriterCtx *ctx, uint8_t *buf, int len);
 static int writeCtxDoRead(WriterCtx *ctx, uint8_t *buf, int len);
 static int writeCtxDoFlush(WriterCtx *ctx);
 
-WriterCtx* writerCtxCreate(WriterType type);
+WriterCtx* writerCtxCreate(WriterType type, bool readOnly);
 void writerCtxDestroy(WriterCtx *w);
 
 typedef uint32_t CheckSummer;
@@ -57,14 +57,16 @@ typedef struct FstCountingWriter {
   CheckSummer summer;  
 } FstCountingWriter;
 
-int fstCountingWriterWrite(FstCountingWriter *write, uint8_t *buf, uint32_t bufLen); 
+int fstCountingWriterWrite(FstCountingWriter *write, uint8_t *buf, uint32_t len); 
+
+int fstCountingWriterRead(FstCountingWriter *write, uint8_t *buf, uint32_t len);
 
 int fstCountingWriterFlush(FstCountingWriter *write);
 
 
 uint32_t fstCountingWriterMaskedCheckSum(FstCountingWriter *write);
 
-FstCountingWriter *fstCountingWriterCreate(void *wtr);
+FstCountingWriter *fstCountingWriterCreate(void *wtr, bool readOnly);
 void fstCountingWriterDestroy(FstCountingWriter *w); 
 
 
diff --git a/source/libs/index/inc/index_fst_util.h b/source/libs/index/inc/index_fst_util.h
index 4af885816f59fd1fbe2f178254ed8f14fdc4e834..24b2508678e4664704ffe4425f779d84a876c296 100644
--- a/source/libs/index/inc/index_fst_util.h
+++ b/source/libs/index/inc/index_fst_util.h
@@ -93,6 +93,28 @@ uint8_t *fstSliceData(FstSlice *s, int32_t *sz);
 
 #define FST_SLICE_LEN(s) (s->end - s->start + 1)
 
+//// stack 
+//
+//typedef (*StackFreeElemFn)(void *elem);
+//
+//typedef struct FstStack {
+//  void   *first;    
+//  void   *end;  
+//  size_t elemSize; 
+//  size_t nElem;
+//  StackFreeElemFn fn;
+//} FstStack;
+//
+//
+//FstStack* fstStackCreate(size_t elemSize, stackFreeElem); 
+//void  *fstStackPush(FstStack *s, void *elem);
+//void  *fstStackTop(FstStack *s);
+//size_t fstStackLen(FstStack *s); 
+//void  fstStackDestory(FstStack *); 
+//
+
+
+  
 #ifdef __cplusplus
 }
 #endif
diff --git a/source/libs/index/src/index_fst.c b/source/libs/index/src/index_fst.c
index 418d1f2bda0bad238ecdaf3eb47118a5fad7789a..0cc95b738d36a25694eb15280346f17aa74b6c47 100644
--- a/source/libs/index/src/index_fst.c
+++ b/source/libs/index/src/index_fst.c
@@ -16,6 +16,7 @@
 #include "index_fst.h"
 #include "tcoding.h"
 #include "tchecksum.h"
+#include "indexInt.h" 
 
 
 static void fstPackDeltaIn(FstCountingWriter *wrt, CompiledAddr nodeAddr, CompiledAddr transAddr, uint8_t nBytes) {
@@ -40,6 +41,7 @@ void unFinishedNodeDestroyElem(void* elem) {
   FstBuilderNodeUnfinished *b = (FstBuilderNodeUnfinished*)elem;
   fstBuilderNodeDestroy(b->node); 
   free(b->last); 
+  b->last = NULL;
 }  
 void fstUnFinishedNodesDestroy(FstUnFinishedNodes *nodes) {
   if (nodes == NULL) { return; } 
@@ -62,15 +64,15 @@ FstBuilderNode *fstUnFinishedNodesPopRoot(FstUnFinishedNodes *nodes) {
   assert(taosArrayGetSize(nodes->stack) == 1);
 
   FstBuilderNodeUnfinished *un = taosArrayPop(nodes->stack);
-  //assert(un->last == NULL); 
+  assert(un->last == NULL); 
   return un->node;  
 }
 
 FstBuilderNode *fstUnFinishedNodesPopFreeze(FstUnFinishedNodes *nodes, CompiledAddr addr) {
   FstBuilderNodeUnfinished *un = taosArrayPop(nodes->stack);
   fstBuilderNodeUnfinishedLastCompiled(un, addr);
-  free(un->last); // TODO add func FstLastTransitionFree()
-  un->last = NULL;
+  //free(un->last); // TODO add func FstLastTransitionFree()
+  //un->last = NULL;
   return un->node; 
 }
 
@@ -147,7 +149,7 @@ uint64_t fstUnFinishedNodesFindCommPrefixAndSetOutput(FstUnFinishedNodes *node,
 
   size_t lsz = (size_t)(s->end - s->start + 1);          // data len 
   size_t ssz = taosArrayGetSize(node->stack);  // stack size
-
+  *out = in;
   uint64_t i = 0;
   for (i = 0; i < lsz && i < ssz; i++) {
     FstBuilderNodeUnfinished *un = taosArrayGet(node->stack, i);
@@ -272,16 +274,16 @@ void fstStateCompileForAnyTrans(FstCountingWriter *w, CompiledAddr addr, FstBuil
     if (FST_BUILDER_NODE_IS_FINAL(node)) {
       fstCountingWriterPackUintIn(w, node->finalOutput, oSize);
     }
-    for (size_t i = 0; i < sz; i++) {
+    for (int32_t i = sz - 1; i >= 0; i--) {
       FstTransition *t = taosArrayGet(node->trans, i);
       fstCountingWriterPackUintIn(w, t->out, oSize);
     }
   } 
-  for (size_t i = 0; i < sz; i++) {
+  for (int32_t i = sz - 1; i >= 0; i--) {
       FstTransition *t = taosArrayGet(node->trans, i);
       fstPackDeltaIn(w, addr, t->addr, tSize);
   }
-  for (size_t i = 0; i < sz; i++) {
+  for (int32_t i = sz - 1; i >= 0; i--) {
      FstTransition *t = taosArrayGet(node->trans, i);
      fstCountingWriterWrite(w, (char *)&t->inp, 1);
       //fstPackDeltaIn(w, addr, t->addr, tSize);
@@ -402,7 +404,7 @@ CompiledAddr fstStateTransAddr(FstState *s, FstNode *node) {
   assert(s->state == OneTransNext || s->state == OneTrans);
   FstSlice *slice = &node->data;
   if (s->state == OneTransNext) {
-    return (CompiledAddr)(node->end);      
+    return (CompiledAddr)(node->end) - 1;      
   } else {
     PackSizes sizes = node->sizes; 
     uint8_t tSizes = FST_GET_TRANSITION_PACK_SIZE(sizes);  
@@ -457,7 +459,7 @@ Output fstStateOutput(FstState *s, FstNode *node) {
   uint8_t tSizes = FST_GET_TRANSITION_PACK_SIZE(node->sizes);
 
   uint64_t i = node->start 
-                - fstStateInputLen(s);
+                - fstStateInputLen(s)
                 - 1
                 - tSizes 
                 - oSizes;
@@ -618,7 +620,7 @@ FstNode *fstNodeCreate(int64_t version, CompiledAddr addr, FstSlice *slice) {
      n->version = version;
      n->state   = st;  
      n->start   = addr;
-     n->end     = fstStateEndAddrForOneTransNext(&st, slice); //? s.end_addr(data); 
+     n->end     = fstStateEndAddrForOneTransNext(&st, &n->data); //? s.end_addr(data); 
      n->isFinal = false;
      n->sizes   = 0;
      n->nTrans  = 1;
@@ -630,23 +632,24 @@ FstNode *fstNodeCreate(int64_t version, CompiledAddr addr, FstSlice *slice) {
      n->version = version; 
      n->state   = st; 
      n->start   = addr;
-     n->end     = fstStateEndAddrForOneTrans(&st, slice, sz); // s.end_addr(data, sz);
+     n->end     = fstStateEndAddrForOneTrans(&st, &data, sz); // s.end_addr(data, sz);
      n->isFinal = false; 
      n->nTrans  = 1; 
      n->sizes   = sz;   
      n->finalOutput = 0; 
   } else {
-     uint64_t sz = fstStateSizes(&st, slice);    // s.sizes(data)
-     uint32_t nTrans = fstStateNtrans(&st, slice); // s.ntrans(data)  
-     n->data    = *slice; 
+     FstSlice data = fstSliceCopy(slice, 0, addr);
+     uint64_t sz = fstStateSizes(&st, &data);    // s.sizes(data)
+     uint32_t nTrans = fstStateNtrans(&st, &data); // s.ntrans(data)  
+     n->data    = data; 
      n->version = version;
      n->state   = st;
      n->start   = addr;
-     n->end     = fstStateEndAddrForAnyTrans(&st, version, slice, sz, nTrans); // s.end_addr(version, data, sz, ntrans);
+     n->end     = fstStateEndAddrForAnyTrans(&st, version, &data, sz, nTrans); // s.end_addr(version, data, sz, ntrans);
      n->isFinal = fstStateIsFinalState(&st); // s.is_final_state();
      n->nTrans  = nTrans;
      n->sizes   = sz;
-     n->finalOutput = fstStateFinalOutput(&st, version, slice, sz, nTrans); // s.final_output(version, data, sz, ntrans);
+     n->finalOutput = fstStateFinalOutput(&st, version, &data, sz, nTrans); // s.final_output(version, data, sz, ntrans);
   }
    return n; 
 }
@@ -769,12 +772,23 @@ FstBuilder *fstBuilderCreate(void *w, FstType ty) {
   if (NULL == b) { return b; }
 
    
-  b->wrt = fstCountingWriterCreate(w);
+  b->wrt = fstCountingWriterCreate(w, false);
   b->unfinished = fstUnFinishedNodesCreate();   
   b->registry   = fstRegistryCreate(10000, 2) ;
   b->last       = fstSliceCreate(NULL, 0);
   b->lastAddr   = NONE_ADDRESS; 
   b->len        = 0;
+  
+  char buf64[8] = {0}; 
+  void *pBuf64 = buf64;
+  taosEncodeFixedU64(&pBuf64, VERSION); 
+  fstCountingWriterWrite(b->wrt, buf64, sizeof(buf64));
+  
+  memset(buf64, 0, sizeof(buf64)); 
+  pBuf64 = buf64;
+  taosEncodeFixedU64(&pBuf64, ty); 
+  fstCountingWriterWrite(b->wrt, buf64, sizeof(buf64));
+
   return b;
 }
 void fstBuilderDestroy(FstBuilder *b) {
@@ -794,6 +808,7 @@ bool fstBuilderInsert(FstBuilder *b, FstSlice bs, Output in) {
     fstBuilderInsertOutput(b, bs, in); 
     return true; 
   } 
+  indexInfo("key must be ordered");
   return false;
 }
 
@@ -810,7 +825,7 @@ void fstBuilderInsertOutput(FstBuilder *b, FstSlice bs, Output in) {
    //   prefixLen = fstUnFinishedNodesFindCommPrefix(b->unfinished, bs);
    //   out = 0;
    //}
-   Output out; 
+   Output out;  
    uint64_t prefixLen = fstUnFinishedNodesFindCommPrefixAndSetOutput(b->unfinished, bs, in, &out);
   
    if (prefixLen == FST_SLICE_LEN(s)) {
@@ -937,9 +952,10 @@ void fstLastTransitionDestroy(FstLastTransition *trn) {
 void fstBuilderNodeUnfinishedLastCompiled(FstBuilderNodeUnfinished *unNode, CompiledAddr addr) {
   FstLastTransition *trn = unNode->last;       
   if (trn == NULL) { return; }  
-
   FstTransition t = {.inp = trn->inp, .out = trn->out, .addr = addr};      
   taosArrayPush(unNode->node->trans, &t); 
+  fstLastTransitionDestroy(trn); 
+  unNode->last = NULL;
   return;
 }
 
@@ -1028,8 +1044,9 @@ bool fstGet(Fst *fst, FstSlice *b, Output *out) {
   for (uint32_t i = 0; i < len; i++) {
     uint8_t inp = data[i];
     Output  res = 0;
-    bool null = fstNodeFindInput(root, inp, &res);    
-    if (null) { return false; }    
+    if (false == fstNodeFindInput(root, inp, &res)) {
+      return false; 
+    }   
 
     FstTransition trn; 
     fstNodeGetTransitionAt(root, res, &trn);
diff --git a/source/libs/index/src/index_fst_counting_writer.c b/source/libs/index/src/index_fst_counting_writer.c
index 6820292e650fd7375a6b358974ea9055779e2efa..9ec346cebc026cba7d03e1cf39890a6c262d1a9a 100644
--- a/source/libs/index/src/index_fst_counting_writer.c
+++ b/source/libs/index/src/index_fst_counting_writer.c
@@ -13,6 +13,7 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 #include "tutil.h"
+#include "indexInt.h"
 #include "index_fst_util.h"
 #include "index_fst_counting_writer.h"
 
@@ -22,7 +23,7 @@ static int writeCtxDoWrite(WriterCtx *ctx, uint8_t *buf, int len) {
   }
 
   if (ctx->type == TFile) {
-    assert(len != tfWrite(ctx->fd, buf, len));
+    assert(len == tfWrite(ctx->fd, buf, len));
   } else {
     memcpy(ctx->mem + ctx->offset, buf, len);
   } 
@@ -30,17 +31,19 @@ static int writeCtxDoWrite(WriterCtx *ctx, uint8_t *buf, int len) {
   return len;
 }
 static int writeCtxDoRead(WriterCtx *ctx, uint8_t *buf, int len) {
+  int nRead = 0; 
   if (ctx->type == TFile) {
-    tfRead(ctx->fd, buf, len);
+    nRead = tfRead(ctx->fd, buf, len);
   } else {
     memcpy(buf, ctx->mem + ctx->offset, len);
   }
-  ctx->offset += len;
+  ctx->offset += nRead;
 
-  return 1;
+  return nRead;
 } 
 static int writeCtxDoFlush(WriterCtx *ctx) {
   if (ctx->type == TFile) {
+    //tfFsync(ctx->fd);
     //tfFlush(ctx->fd);
   } else {
     // do nothing
@@ -48,15 +51,21 @@ static int writeCtxDoFlush(WriterCtx *ctx) {
   return 1;
 }
 
-WriterCtx* writerCtxCreate(WriterType type) {     
+WriterCtx* writerCtxCreate(WriterType type, bool readOnly) {     
   WriterCtx *ctx = calloc(1, sizeof(WriterCtx));
   if (ctx == NULL) { return NULL; }
 
   ctx->type = type;
   if (ctx->type == TFile) {
-    ctx->fd = tfOpenCreateWriteAppend(tmpFile);  
+    tfInit();
+    // ugly code, refactor later
+    if (readOnly == false) {
+      ctx->fd = tfOpenCreateWriteAppend(tmpFile);  
+    } else {
+      ctx->fd = tfOpenReadWrite(tmpFile);
+    } 
     if (ctx->fd < 0) {
-      
+      indexError("open file error %d", errno);       
     }
   } else if (ctx->type == TMemory) {
     ctx->mem = calloc(1, DefaultMem * sizeof(uint8_t));
@@ -75,33 +84,43 @@ void writerCtxDestroy(WriterCtx *ctx) {
     free(ctx->mem);
   } else {
     tfClose(ctx->fd);    
+    tfCleanup();
   }
   free(ctx);
 }
 
 
-FstCountingWriter *fstCountingWriterCreate(void *wrt) {
+FstCountingWriter *fstCountingWriterCreate(void *wrt, bool readOnly) {
   FstCountingWriter *cw = calloc(1, sizeof(FstCountingWriter)); 
   if (cw == NULL) { return NULL; }
   
-  cw->wrt = (void *)(writerCtxCreate(TFile)); 
+  cw->wrt = (void *)(writerCtxCreate(TFile, readOnly)); 
   return cw; 
 }
 void fstCountingWriterDestroy(FstCountingWriter *cw) {
   // free wrt object: close fd or free mem 
+  fstCountingWriterFlush(cw);
   writerCtxDestroy((WriterCtx *)(cw->wrt));
   free(cw);
 }
 
-int fstCountingWriterWrite(FstCountingWriter *write, uint8_t *buf, uint32_t bufLen) {
+int fstCountingWriterWrite(FstCountingWriter *write, uint8_t *buf, uint32_t len) {
   if (write == NULL) { return 0; } 
   // update checksum 
   // write data to file/socket or mem
   WriterCtx *ctx = write->wrt;
 
-  int nWrite = ctx->write(ctx, buf, bufLen); 
-  write->count += nWrite;
-  return bufLen; 
+  int nWrite = ctx->write(ctx, buf, len); 
+  assert(nWrite == len);
+  write->count += len;
+  return len; 
+} 
+int fstCountingWriterRead(FstCountingWriter *write, uint8_t *buf, uint32_t len) {
+  if (write == NULL) { return 0; }
+  WriterCtx *ctx = write->wrt;
+  int nRead = ctx->read(ctx, buf, len);
+  //assert(nRead == len);
+  return nRead; 
 } 
 
 uint32_t fstCountingWriterMaskedCheckSum(FstCountingWriter *write) {
diff --git a/source/libs/index/src/index_fst_util.c b/source/libs/index/src/index_fst_util.c
index 532b0b8ac3704ae88449959b6739e8bc6b436011..c933c6d23b2eed040bcf9fd276d783c13b7ad025 100644
--- a/source/libs/index/src/index_fst_util.c
+++ b/source/libs/index/src/index_fst_util.c
@@ -67,7 +67,7 @@ uint8_t packSize(uint64_t n) {
 }
 
 uint64_t unpackUint64(uint8_t *ch, uint8_t sz) {
-  uint64_t n;
+  uint64_t n = 0;
   for (uint8_t i = 0; i < sz; i++) {
     n = n | (ch[i] << (8 * i));
   }
@@ -174,5 +174,18 @@ int fstSliceCompare(FstSlice *a, FstSlice *b) {
   else { return 0; } 
 } 
 
+//FstStack* fstStackCreate(size_t elemSize, StackFreeElem freeFn) {
+//  FstStack *s = calloc(1, sizeof(FstStack));
+//  if (s == NULL) { return NULL; }
+//  s-> 
+//  s->freeFn 
+//  
+//}
+//void  *fstStackPush(FstStack *s, void *elem);
+//void  *fstStackTop(FstStack *s);
+//size_t fstStackLen(FstStack *s); 
+//void  *fstStackGetAt(FstStack *s, size_t i);
+//void   fstStackDestory(FstStack *); 
+
 
 
diff --git a/source/libs/index/test/indexTests.cpp b/source/libs/index/test/indexTests.cpp
index 14ff2caf120d8700472eb9d9876bad753471a225..858861529d5bdb60a3dcdcef43440b7676404a06 100644
--- a/source/libs/index/test/indexTests.cpp
+++ b/source/libs/index/test/indexTests.cpp
@@ -63,19 +63,67 @@
 //}
 
 int main(int argc, char** argv) {
-  std::string str("abc");
-  FstSlice key = fstSliceCreate((uint8_t *)str.c_str(), str.size());
-  Output   val = 1;
+  // test write
+  FstBuilder *b = fstBuilderCreate(NULL, 0);
+  {
+    std::string str("aaa");
+    FstSlice key = fstSliceCreate((uint8_t *)str.c_str(), str.size());
+    Output   val = 1;
+    fstBuilderInsert(b, key, val); 
+  }
 
   //std::string str1("bcd");
   //FstSlice key1 = fstSliceCreate((uint8_t *)str1.c_str(), str1.size());
   //Output   val2 = 10;
-  FstBuilder *b = fstBuilderCreate(NULL, 1);
-  fstBuilderInsert(b, key, val); 
-  //fstBuilderInsert(b, key1, val2); 
+  //
+   
+  {
+     
+    for (size_t i = 1; i < 26; i++) {
+      std::string str("aaa");
+      str[2] = 'a' + i ;
+      FstSlice key = fstSliceCreate((uint8_t *)str.c_str(), str.size());
+      Output   val = 2;
+      fstBuilderInsert(b, key, val); 
+    }
+    
+  } 
   fstBuilderFinish(b);
   fstBuilderDestroy(b);
-  fstSliceDestroy(&key);
+
+
+  char buf[64 * 1024] = {0};     
+
+  FstSlice s; 
+
+  FstCountingWriter *w = fstCountingWriterCreate(NULL, true);
+  int nRead = fstCountingWriterRead(w, (uint8_t *)buf, sizeof(buf)); 
+  assert(nRead <= sizeof(buf));  
+  s = fstSliceCreate((uint8_t *)buf, nRead);
+  fstCountingWriterDestroy(w);
+
+
+  // test reader
+  
+      
+  Fst *fst = fstCreate(&s); 
+  {
+    std::string str("aaa"); 
+    uint64_t out;
+    
+   
+    FstSlice key = fstSliceCreate((uint8_t *)str.c_str(), str.size());
+    bool ok = fstGet(fst, &key, &out); 
+    if (ok == true) {
+      //indexInfo("Get key-value success, %s, %d", str.c_str(), out); 
+    } else {
+      //indexError("Get key-value failed, %s", str.c_str()); 
+    }
+  }
+  fstSliceDestroy(&s);
+  
+
+  
   return 1;
 }