diff --git a/source/libs/index/inc/index_fst.h b/source/libs/index/inc/index_fst.h
index fe669c8567..cd5073187c 100644
--- a/source/libs/index/inc/index_fst.h
+++ b/source/libs/index/inc/index_fst.h
@@ -268,11 +268,8 @@ FstNode*     fstGetNode(Fst *fst, CompiledAddr);
 FstNode*     fstGetRoot(Fst *fst);
 FstType      fstGetType(Fst *fst); 
 CompiledAddr fstGetRootAddr(Fst *fst);
-
-
-
-Output fstEmptyFinalOutput(Fst *fst, bool *null);
-bool fstVerify(Fst *fst);
+Output       fstEmptyFinalOutput(Fst *fst, bool *null);
+bool         fstVerify(Fst *fst);
 
 
 //refactor this function 
@@ -304,6 +301,7 @@ typedef struct StreamWithStateResult {
 } StreamWithStateResult;
 
 StreamWithStateResult *swsResultCreate(FstSlice *data, FstOutput fOut, void *state);
+void swsResultDestroy(StreamWithStateResult *result);
 
 typedef void* (*StreamCallback)(void *);
 StreamWithState *streamWithStateCreate(Fst *fst, Automation *automation, FstBoundWithData *min, FstBoundWithData *max) ;
diff --git a/source/libs/index/src/index_fst.c b/source/libs/index/src/index_fst.c
index ca1c7910ed..68d2011b8f 100644
--- a/source/libs/index/src/index_fst.c
+++ b/source/libs/index/src/index_fst.c
@@ -1301,12 +1301,16 @@ StreamWithStateResult *streamWithStateNextWith(StreamWithState *sws, StreamCallb
     if (fstBoundWithDataExceededBy(sws->endAt, &slice)) {
       taosArrayDestroyEx(sws->stack, streamStateDestroy);
       sws->stack = (SArray *)taosArrayInit(256, sizeof(StreamState)); 
+      fstSliceDestroy(&slice);
       return NULL;
     }
     if (FST_NODE_IS_FINAL(nextNode) && isMatch) {
       FstOutput fOutput = {.null = false, .out = out + FST_NODE_FINAL_OUTPUT(nextNode)};
-      return swsResultCreate(&slice, fOutput , tState);
+      StreamWithStateResult *result =  swsResultCreate(&slice, fOutput , tState);     
+      fstSliceDestroy(&slice);
+      return result; 
     }
+    fstSliceDestroy(&slice);
   }
   return NULL; 
   
@@ -1321,8 +1325,14 @@ StreamWithStateResult *swsResultCreate(FstSlice *data, FstOutput fOut, void *sta
   result->state = state; 
 
   return result;
-   
 }
+void swsResultDestroy(StreamWithStateResult *result) {
+  if (NULL == result) { return; }
+  
+  fstSliceDestroy(&result->data);
+  free(result);
+}
+
 void streamStateDestroy(void *s) {
   if (NULL == s) { return; }
   StreamState *ss = (StreamState *)s;
diff --git a/source/libs/index/src/index_fst_util.c b/source/libs/index/src/index_fst_util.c
index 1c7a1a9e9d..532b0b8ac3 100644
--- a/source/libs/index/src/index_fst_util.c
+++ b/source/libs/index/src/index_fst_util.c
@@ -107,7 +107,6 @@ FstSlice fstSliceCreate(uint8_t *data, uint64_t len) {
 FstSlice fstSliceCopy(FstSlice *s, int32_t start, int32_t end) {
   FstString *str = s->str;
   str->ref++;
-  int32_t alen; 
   //uint8_t *buf = fstSliceData(s, &alen); 
   //start = buf + start - (buf - s->start);
   //end   = buf + end - (buf - s->start);  
@@ -117,9 +116,10 @@ FstSlice fstSliceCopy(FstSlice *s, int32_t start, int32_t end) {
 }
 FstSlice fstSliceDeepCopy(FstSlice *s, int32_t start, int32_t end) {
 
-  int32_t alen, tlen = end - start + 1;
-  uint8_t *data = fstSliceData(s, &alen);      
-  assert(tlen <= alen);
+  int32_t tlen = end - start + 1;
+  int32_t slen;
+  uint8_t *data = fstSliceData(s, &slen);      
+  assert(tlen <= slen);
 
   uint8_t *buf  = malloc(sizeof(uint8_t) * tlen);  
   memcpy(buf, data + start, tlen);
@@ -136,7 +136,7 @@ FstSlice fstSliceDeepCopy(FstSlice *s, int32_t start, int32_t end) {
   return ans; 
 }
 bool fstSliceIsEmpty(FstSlice *s) {
-  return s->str == NULL || s->start < 0 || s->end < 0;
+  return s->str == NULL || s->str->len == 0 || s->start < 0 || s->end < 0;
 }
 
 uint8_t *fstSliceData(FstSlice *s, int32_t *size) {
@@ -161,7 +161,6 @@ int fstSliceCompare(FstSlice *a, FstSlice *b) {
   uint8_t *aBuf = fstSliceData(a, &alen); 
   uint8_t *bBuf = fstSliceData(b, &blen); 
 
-
   uint32_t i, j;
   for (i = 0, j = 0; i < alen && j < blen; i++, j++) {
     uint8_t x = aBuf[i];