diff --git a/source/libs/executor/inc/dataSinkMgt.h b/include/libs/executor/dataSinkMgt.h
similarity index 80%
rename from source/libs/executor/inc/dataSinkMgt.h
rename to include/libs/executor/dataSinkMgt.h
index d13423b25d..a0819fcf85 100644
--- a/source/libs/executor/inc/dataSinkMgt.h
+++ b/include/libs/executor/dataSinkMgt.h
@@ -21,13 +21,11 @@ extern "C" {
 #endif
 
 #include "os.h"
-#include "executorimpl.h"
+#include "thash.h"
 
-#define DS_CAPACITY_ENOUGH 1
-#define DS_CAPACITY_FULL   2
-#define DS_NEED_SCHEDULE   3
-#define DS_END             4
-#define DS_IN_PROCESS      5
+#define DS_BUF_LOW   1
+#define DS_BUF_FULL  2
+#define DS_BUF_EMPTY 3
 
 struct SDataSink;
 struct SSDataBlock;
@@ -42,15 +40,20 @@ int32_t dsDataSinkMgtInit(SDataSinkMgtCfg *cfg);
 typedef void* DataSinkHandle;
 
 typedef struct SInputData {
-  const SSDataBlock* pData;
+  const struct SSDataBlock* pData;
   SHashObj* pTableRetrieveTsMap;
 } SInputData;
 
-typedef struct SOutPutData {
+typedef struct SOutputData {
   int32_t numOfRows;
   int8_t  compressed;
   char*   pData;
-} SOutPutData;
+  bool    queryEnd;
+  bool    needSchedule;
+  int32_t bufStatus;
+  int64_t useconds;
+  int8_t  precision;
+} SOutputData;
 
 /**
  * Create a subplan's datasinker handle for all later operations. 
@@ -66,16 +69,16 @@ int32_t dsCreateDataSinker(const struct SDataSink *pDataSink, DataSinkHandle* pH
  * @param pRes
  * @return error code
  */
-int32_t dsPutDataBlock(DataSinkHandle handle, const SInputData* pInput, int32_t* pStatus);
+int32_t dsPutDataBlock(DataSinkHandle handle, const SInputData* pInput, bool* pContinue);
 
-void dsEndPut(DataSinkHandle handle);
+void dsEndPut(DataSinkHandle handle, int64_t useconds);
 
 /**
  * Get the length of the data returned by the next call to dsGetDataBlock.
  * @param handle
- * @return data length
+ * @param pLen data length
  */
-int32_t dsGetDataLength(DataSinkHandle handle, int32_t* pStatus);
+void dsGetDataLength(DataSinkHandle handle, int32_t* pLen, bool* pQueryEnd);
 
 /**
  * Get data, the caller needs to allocate data memory.
@@ -84,7 +87,7 @@ int32_t dsGetDataLength(DataSinkHandle handle, int32_t* pStatus);
  * @param pStatus output
  * @return error code
  */
-int32_t dsGetDataBlock(DataSinkHandle handle, SOutPutData* pOutput, int32_t* pStatus);
+int32_t dsGetDataBlock(DataSinkHandle handle, SOutputData* pOutput);
 
 /**
  * After dsGetStatus returns DS_NEED_SCHEDULE, the caller need to put this into the work queue.
diff --git a/source/libs/executor/inc/dataSinkInt.h b/source/libs/executor/inc/dataSinkInt.h
index 1bbf5494dd..69727626af 100644
--- a/source/libs/executor/inc/dataSinkInt.h
+++ b/source/libs/executor/inc/dataSinkInt.h
@@ -31,10 +31,10 @@ typedef struct SDataSinkManager {
   pthread_mutex_t mutex;
 } SDataSinkManager;
 
-typedef int32_t (*FPutDataBlock)(struct SDataSinkHandle* pHandle, const SInputData* pInput, int32_t* pStatus);
-typedef void (*FEndPut)(struct SDataSinkHandle* pHandle);
-typedef int32_t (*FGetDataLength)(struct SDataSinkHandle* pHandle, int32_t* pStatus);
-typedef int32_t (*FGetDataBlock)(struct SDataSinkHandle* pHandle, SOutPutData* pOutput, int32_t* pStatus);
+typedef int32_t (*FPutDataBlock)(struct SDataSinkHandle* pHandle, const SInputData* pInput, bool* pContinue);
+typedef void (*FEndPut)(struct SDataSinkHandle* pHandle, int64_t useconds);
+typedef void (*FGetDataLength)(struct SDataSinkHandle* pHandle, int32_t* pLen, bool* pQueryEnd);
+typedef int32_t (*FGetDataBlock)(struct SDataSinkHandle* pHandle, SOutputData* pOutput);
 typedef int32_t (*FDestroyDataSinker)(struct SDataSinkHandle* pHandle);
 
 typedef struct SDataSinkHandle {
diff --git a/source/libs/executor/src/dataDispatcher.c b/source/libs/executor/src/dataDispatcher.c
index 3d8e51d04d..e4b0557bff 100644
--- a/source/libs/executor/src/dataDispatcher.c
+++ b/source/libs/executor/src/dataDispatcher.c
@@ -19,6 +19,7 @@
 #include "tcompression.h"
 #include "tglobal.h"
 #include "tqueue.h"
+#include "executorimpl.h"
 
 #define DATA_META_LENGTH(tables) (sizeof(int32_t) + sizeof(STableIdInfo) * taosHashGetSize(tables) + sizeof(SRetrieveTableRsp))
 
@@ -42,6 +43,8 @@ typedef struct SDataDispatchHandle {
   STaosQueue* pDataBlocks;
   SDataDispatchBuf nextOutput;
   int32_t status;
+  bool queryEnd;
+  int64_t useconds;
   pthread_mutex_t mutex;
 } SDataDispatchHandle;
 
@@ -124,7 +127,9 @@ static bool allocBuf(SDataDispatchHandle* pDispatcher, const SInputData* pInput,
 
 static int32_t updateStatus(SDataDispatchHandle* pDispatcher) {
   pthread_mutex_lock(&pDispatcher->mutex);
-  int32_t status = taosQueueSize(pDispatcher->pDataBlocks) < pDispatcher->pManager->cfg.maxDataBlockNumPerQuery ? DS_CAPACITY_ENOUGH : DS_CAPACITY_FULL;
+  int32_t blockNums = taosQueueSize(pDispatcher->pDataBlocks);
+  int32_t status = (0 == blockNums ? DS_BUF_EMPTY :
+      (blockNums < pDispatcher->pManager->cfg.maxDataBlockNumPerQuery ? DS_BUF_LOW : DS_BUF_FULL));
   pDispatcher->status = status;
   pthread_mutex_unlock(&pDispatcher->mutex);
   return status;
@@ -137,7 +142,7 @@ static int32_t getStatus(SDataDispatchHandle* pDispatcher) {
   return status;
 }
 
-static int32_t putDataBlock(SDataSinkHandle* pHandle, const SInputData* pInput, int32_t* pStatus) {
+static int32_t putDataBlock(SDataSinkHandle* pHandle, const SInputData* pInput, bool* pContinue) {
   SDataDispatchHandle* pDispatcher = (SDataDispatchHandle*)pHandle;
   SDataDispatchBuf* pBuf = taosAllocateQitem(sizeof(SDataDispatchBuf));
   if (NULL == pBuf || !allocBuf(pDispatcher, pInput, pBuf)) {
@@ -145,38 +150,46 @@ static int32_t putDataBlock(SDataSinkHandle* pHandle, const SInputData* pInput,
   }
   toDataCacheEntry(pDispatcher, pInput, pBuf);
   taosWriteQitem(pDispatcher->pDataBlocks, pBuf);
-  *pStatus = updateStatus(pDispatcher);
+  *pContinue = (DS_BUF_LOW == updateStatus(pDispatcher) ? true : false);
   return TSDB_CODE_SUCCESS;
 }
 
-static void endPut(struct SDataSinkHandle* pHandle) {
+static void endPut(struct SDataSinkHandle* pHandle, int64_t useconds) {
   SDataDispatchHandle* pDispatcher = (SDataDispatchHandle*)pHandle;
   pthread_mutex_lock(&pDispatcher->mutex);
-  pDispatcher->status = DS_END;
+  pDispatcher->queryEnd = true;
+  pDispatcher->useconds = useconds;
   pthread_mutex_unlock(&pDispatcher->mutex);
 }
 
-static int32_t getDataLength(SDataSinkHandle* pHandle, int32_t* pStatus) {
+static void getDataLength(SDataSinkHandle* pHandle, int32_t* pLen, bool* pQueryEnd) {
   SDataDispatchHandle* pDispatcher = (SDataDispatchHandle*)pHandle;
   if (taosQueueEmpty(pDispatcher->pDataBlocks)) {
-    *pStatus = getStatus(pDispatcher) ? DS_END : DS_IN_PROCESS;
-    return 0;
+    *pQueryEnd = pDispatcher->queryEnd;
+    *pLen = 0;
+    return;
   }
   SDataDispatchBuf* pBuf = NULL;
   taosReadQitem(pDispatcher->pDataBlocks, (void**)&pBuf);
   memcpy(&pDispatcher->nextOutput, pBuf, sizeof(SDataDispatchBuf));
   taosFreeQitem(pBuf);
-  return ((SDataCacheEntry*)(pDispatcher->nextOutput.pData))->dataLen;
+  *pLen = ((SDataCacheEntry*)(pDispatcher->nextOutput.pData))->dataLen;
 }
 
-static int32_t getDataBlock(SDataSinkHandle* pHandle, SOutPutData* pOutput, int32_t* pStatus) {
+static int32_t getDataBlock(SDataSinkHandle* pHandle, SOutputData* pOutput) {
   SDataDispatchHandle* pDispatcher = (SDataDispatchHandle*)pHandle;
   SDataCacheEntry* pEntry = (SDataCacheEntry*)(pDispatcher->nextOutput.pData);
   memcpy(pOutput->pData, pEntry->data, pEntry->dataLen);
   pOutput->numOfRows = pEntry->numOfRows;
   pOutput->compressed = pEntry->compressed;
   tfree(pDispatcher->nextOutput.pData);  // todo persistent
-  *pStatus = updateStatus(pDispatcher);
+  pOutput->bufStatus = updateStatus(pDispatcher);
+  pthread_mutex_lock(&pDispatcher->mutex);
+  pOutput->queryEnd = pDispatcher->queryEnd;
+  pOutput->needSchedule = false;
+  pOutput->useconds = pDispatcher->useconds;
+  pOutput->precision = pDispatcher->schema.precision;
+  pthread_mutex_unlock(&pDispatcher->mutex);
   return TSDB_CODE_SUCCESS;
 }
 
@@ -205,7 +218,8 @@ int32_t createDataDispatcher(SDataSinkManager* pManager, const SDataSink* pDataS
   dispatcher->sink.fDestroy = destroyDataSinker;
   dispatcher->pManager = pManager;
   dispatcher->schema = pDataSink->schema;
-  dispatcher->status = DS_CAPACITY_ENOUGH;
+  dispatcher->status = DS_BUF_EMPTY;
+  dispatcher->queryEnd = false;
   dispatcher->pDataBlocks = taosOpenQueue();
   pthread_mutex_init(&dispatcher->mutex, NULL);
   if (NULL == dispatcher->pDataBlocks) {
diff --git a/source/libs/executor/src/dataSinkMgt.c b/source/libs/executor/src/dataSinkMgt.c
index 8a96c5d05f..e3f0cd7eaa 100644
--- a/source/libs/executor/src/dataSinkMgt.c
+++ b/source/libs/executor/src/dataSinkMgt.c
@@ -31,24 +31,24 @@ int32_t dsCreateDataSinker(const struct SDataSink *pDataSink, DataSinkHandle* pH
   return TSDB_CODE_FAILED;
 }
 
-int32_t dsPutDataBlock(DataSinkHandle handle, const SInputData* pInput, int32_t* pStatus) {
+int32_t dsPutDataBlock(DataSinkHandle handle, const SInputData* pInput, bool* pContinue) {
   SDataSinkHandle* pHandleImpl = (SDataSinkHandle*)handle;
-  return pHandleImpl->fPut(pHandleImpl, pInput, pStatus);
+  return pHandleImpl->fPut(pHandleImpl, pInput, pContinue);
 }
 
-void dsEndPut(DataSinkHandle handle) {
+void dsEndPut(DataSinkHandle handle, int64_t useconds) {
   SDataSinkHandle* pHandleImpl = (SDataSinkHandle*)handle;
-  return pHandleImpl->fEndPut(pHandleImpl);
+  return pHandleImpl->fEndPut(pHandleImpl, useconds);
 }
 
-int32_t dsGetDataLength(DataSinkHandle handle, int32_t* pStatus) {
+void dsGetDataLength(DataSinkHandle handle, int32_t* pLen, bool* pQueryEnd) {
   SDataSinkHandle* pHandleImpl = (SDataSinkHandle*)handle;
-  return pHandleImpl->fGetLen(pHandleImpl, pStatus);
+  pHandleImpl->fGetLen(pHandleImpl, pLen, pQueryEnd);
 }
 
-int32_t dsGetDataBlock(DataSinkHandle handle, SOutPutData* pOutput, int32_t* pStatus) {
+int32_t dsGetDataBlock(DataSinkHandle handle, SOutputData* pOutput) {
   SDataSinkHandle* pHandleImpl = (SDataSinkHandle*)handle;
-  return pHandleImpl->fGetData(pHandleImpl, pOutput, pStatus);
+  return pHandleImpl->fGetData(pHandleImpl, pOutput);
 }
 
 void dsScheduleProcess(void* ahandle, void* pItem) {
diff --git a/source/libs/wal/src/walMeta.c b/source/libs/wal/src/walMeta.c
index ab3aa02f4a..cac80c0a5f 100644
--- a/source/libs/wal/src/walMeta.c
+++ b/source/libs/wal/src/walMeta.c
@@ -13,7 +13,6 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
-#define _DEFAULT_SOURCE
 #include "cJSON.h"
 #include "os.h"
 #include "taoserror.h"
@@ -33,6 +32,24 @@ static inline int walBuildMetaName(SWal* pWal, int metaVer, char* buf) {
   return sprintf(buf, "%s/meta-ver%d", pWal->path, metaVer);
 }
 
+void* tmemmem(char* haystack, int hlen, char* needle, int nlen) {
+  char* limit;
+
+  if (nlen == 0 || hlen < nlen) {
+    return false;
+  }
+
+  limit = haystack + hlen - nlen + 1;
+  while ((haystack = (char*)memchr(
+              haystack, needle[0], limit - haystack)) != NULL) {
+    if (memcmp(haystack, needle, nlen) == 0) {
+      return haystack;
+    }
+    haystack++;
+  }
+  return NULL;
+}
+
 static inline int64_t walScanLogGetLastVer(SWal* pWal) {
   ASSERT(pWal->fileInfoSet != NULL);
   int sz = taosArrayGetSize(pWal->fileInfoSet);
@@ -47,7 +64,8 @@ static inline int64_t walScanLogGetLastVer(SWal* pWal) {
 
   struct stat statbuf;
   stat(fnameStr, &statbuf);
-  int readSize = MIN(WAL_MAX_SIZE, statbuf.st_size);
+  int readSize = MIN(WAL_MAX_SIZE + 2, statbuf.st_size);
+  pLastFileInfo->fileSize = statbuf.st_size;
 
   FileFd fd = taosOpenFileRead(fnameStr);
   if (fd < 0) {
@@ -64,6 +82,7 @@ static inline int64_t walScanLogGetLastVer(SWal* pWal) {
     return -1;
   }
 
+  taosLSeekFile(fd, -readSize, SEEK_END);
   if (readSize != taosReadFile(fd, buf, readSize)) {
     free(buf);
     taosCloseFile(fd);
@@ -71,21 +90,25 @@ static inline int64_t walScanLogGetLastVer(SWal* pWal) {
     return -1;
   }
   
-  char* found = strstr(buf, (const char*)&magic);
-  if (found == NULL) {
-    ASSERT(false);
-    // file has to be deleted
-    free(buf);
-    taosCloseFile(fd);
-    terrno = TSDB_CODE_WAL_FILE_CORRUPTED;
-    return -1;
-  }
-  char *another;
-  while((another = strstr(found + 1, (const char*)&magic)) != NULL) {
+  char* haystack = buf;
+  char* found = NULL;
+  char *candidate;
+  while((candidate = tmemmem(haystack, readSize - (haystack - buf), (char*)&magic, sizeof(uint64_t))) != NULL) {
     // read and validate
-    SWalHead *logContent = (SWalHead*)another;
+    SWalHead *logContent = (SWalHead*)candidate;
     if (walValidHeadCksum(logContent) == 0 && walValidBodyCksum(logContent) == 0) {
-      found = another;
+      found = candidate;
+    }
+    haystack = candidate + 1;
+  }
+  if (found == buf) {
+    SWalHead *logContent = (SWalHead*)found;
+    if (walValidHeadCksum(logContent) != 0 || walValidBodyCksum(logContent) != 0) {
+      // file has to be deleted
+      free(buf);
+      taosCloseFile(fd);
+      terrno = TSDB_CODE_WAL_FILE_CORRUPTED;
+      return -1;
     }
   }
   taosCloseFile(fd);
@@ -120,7 +143,6 @@ int walCheckAndRepairMeta(SWal* pWal) {
       SWalFileInfo fileInfo;
       memset(&fileInfo, -1, sizeof(SWalFileInfo));
       sscanf(name, "%" PRId64 ".log", &fileInfo.firstVer);
-      FileFd fd = taosOpenFileRead(ent->d_name);
       //get lastVer
       //get size
       taosArrayPush(pLogInfoArray, &fileInfo);
@@ -137,28 +159,25 @@ int walCheckAndRepairMeta(SWal* pWal) {
   }
   int newSz = taosArrayGetSize(pLogInfoArray);
   // case 1. meta file not exist / cannot be parsed
-  if (pWal->fileInfoSet == NULL && newSz != 0) {
-    // recover fileInfo set
-    pWal->fileInfoSet = pLogInfoArray;
-    if (newSz != 0) {
-    // recover meta version
-      pWal->vers.firstVer = ((SWalFileInfo*)taosArrayGet(pLogInfoArray, 0))->firstVer;
-      pWal->writeCur = newSz - 1;
-    }
-    // recover file size
-  } else if (oldSz < newSz) {
+  if (oldSz < newSz) {
     for (int i = oldSz; i < newSz; i++) {
       SWalFileInfo *pFileInfo = taosArrayGet(pLogInfoArray, i);
       taosArrayPush(pWal->fileInfoSet, pFileInfo);
     }
+
     pWal->writeCur = newSz - 1;
+    pWal->vers.firstVer = ((SWalFileInfo*)taosArrayGet(pLogInfoArray, 0))->firstVer;
+    pWal->vers.lastVer = walScanLogGetLastVer(pWal);
+    ((SWalFileInfo*)taosArrayGetLast(pWal->fileInfoSet))->lastVer = pWal->vers.lastVer;
+    ASSERT(pWal->vers.lastVer != -1);
+
+    int code = walSaveMeta(pWal);
+    if (code < 0) {
+      taosArrayDestroy(pLogInfoArray);
+      return -1;
+    }
   }
   
-  if (pWal->fileInfoSet && taosArrayGetSize(pWal->fileInfoSet) != 0) {
-    pWal->vers.lastVer = walScanLogGetLastVer(pWal);
-    ASSERT(pWal->vers.lastVer != -1);
-  }
-
   // case 2. versions in meta not match log 
   //         or some log not included in meta
   // (e.g. program killed)
@@ -182,14 +201,11 @@ int walCheckAndRepairMeta(SWal* pWal) {
   }
 #endif
 
-  int code = walSaveMeta(pWal);
-  if (code < 0) {
-    return -1;
-  }
 
   // get last version of this file
   //
   // rebuild meta
+  taosArrayDestroy(pLogInfoArray);
   return 0;
 }
 
@@ -397,6 +413,10 @@ int walLoadMeta(SWal* pWal) {
   }
   memset(buf, 0, size + 5);
   FileFd fd = taosOpenFileRead(fnameStr);
+  if (fd < 0) {
+    terrno = TSDB_CODE_WAL_FILE_CORRUPTED;
+    return -1;
+  }
   if (taosReadFile(fd, buf, size) != size) {
     terrno = TAOS_SYSTEM_ERROR(errno);
     taosCloseFile(fd);
diff --git a/source/libs/wal/src/walMgmt.c b/source/libs/wal/src/walMgmt.c
index d12acb52c6..d5c28d9d9b 100644
--- a/source/libs/wal/src/walMgmt.c
+++ b/source/libs/wal/src/walMgmt.c
@@ -106,6 +106,7 @@ SWal *walOpen(const char *path, SWalCfg *pCfg) {
   // init write buffer
   memset(&pWal->writeHead, 0, sizeof(SWalHead));
   pWal->writeHead.head.headVer = WAL_HEAD_VER;
+  pWal->writeHead.magic = WAL_MAGIC;
 
   if (pthread_mutex_init(&pWal->mutex, NULL) < 0) {
     taosArrayDestroy(pWal->fileInfoSet);
@@ -121,7 +122,9 @@ SWal *walOpen(const char *path, SWalCfg *pCfg) {
     return NULL;
   }
 
-  if (walLoadMeta(pWal) < 0 && walCheckAndRepairMeta(pWal) < 0) {
+  walLoadMeta(pWal);
+
+  if (walCheckAndRepairMeta(pWal) < 0) {
     taosRemoveRef(tsWal.refSetId, pWal->refId);
     pthread_mutex_destroy(&pWal->mutex);
     taosArrayDestroy(pWal->fileInfoSet);
@@ -130,6 +133,7 @@ SWal *walOpen(const char *path, SWalCfg *pCfg) {
   }
 
   if (walCheckAndRepairIdx(pWal) < 0) {
+
   }
 
   wDebug("vgId:%d, wal:%p is opened, level:%d fsyncPeriod:%d", pWal->cfg.vgId, pWal, pWal->cfg.level,
diff --git a/source/libs/wal/test/walMetaTest.cpp b/source/libs/wal/test/walMetaTest.cpp
index a95c75b11d..b65a200ca1 100644
--- a/source/libs/wal/test/walMetaTest.cpp
+++ b/source/libs/wal/test/walMetaTest.cpp
@@ -340,7 +340,10 @@ TEST_F(WalRetentionEnv, repairMeta1) {
   char buf[100];
   sprintf(buf, "%s/meta-ver%d", pathName, 0);
   remove(buf);
+  sprintf(buf, "%s/meta-ver%d", pathName, 1);
+  remove(buf);
   SetUp();
+  //getchar();
 
   ASSERT_EQ(pWal->vers.lastVer, 99);
 
@@ -377,4 +380,26 @@ TEST_F(WalRetentionEnv, repairMeta1) {
     ASSERT_EQ(code, 0);
   }
 
+  for (int i = 0; i < 1000; i++) {
+    int ver = rand() % 200;
+    code = walReadWithHandle(pRead, ver);
+    ASSERT_EQ(code, 0);
+
+    // printf("rrbody: \n");
+    // for(int i = 0; i < pRead->pHead->head.len; i++) {
+    // printf("%d ", pRead->pHead->head.body[i]);
+    //}
+    // printf("\n");
+
+    ASSERT_EQ(pRead->pHead->head.version, ver);
+    ASSERT_EQ(pRead->curVersion, ver + 1);
+    char newStr[100];
+    sprintf(newStr, "%s-%d", ranStr, ver);
+    int len = strlen(newStr);
+    ASSERT_EQ(pRead->pHead->head.len, len);
+    for (int j = 0; j < len; j++) {
+      EXPECT_EQ(newStr[j], pRead->pHead->head.body[j]);
+    }
+  }
+
 }
diff --git a/tests/script/sim/db/basic1.sim b/tests/script/sim/db/basic1.sim
index 52af7d93ea..33af1c5b59 100644
--- a/tests/script/sim/db/basic1.sim
+++ b/tests/script/sim/db/basic1.sim
@@ -85,7 +85,6 @@ if $data02 != 2 then
   return -1
 endi
 
-return
 system sh/exec.sh -n dnode1 -s stop -x SIGKILL
 system sh/exec.sh -n dnode1 -s start
 
@@ -104,4 +103,4 @@ if $rows != 2 then
   return -1
 endi
 
-system sh/exec.sh -n dnode1 -s stop -x SIGINT
\ No newline at end of file
+system sh/exec.sh -n dnode1 -s stop -x SIGINT