diff --git a/src/inc/query.h b/src/inc/query.h
index fb9cbff858..28bd14e66f 100644
--- a/src/inc/query.h
+++ b/src/inc/query.h
@@ -76,6 +76,9 @@ void* qGetResultRetrieveMsg(qinfo_t qinfo);
  */
 int32_t qKillQuery(qinfo_t qinfo);
 
+//kill by qid 
+int32_t qKillQueryByQId(void* pMgmt, int64_t qId, int32_t waitMs, int32_t waitCount);
+
 int32_t qQueryCompleted(qinfo_t qinfo);
 
 /**
@@ -94,6 +97,15 @@ void** qReleaseQInfo(void* pMgmt, void* pQInfo, bool freeHandle);
 bool checkQIdEqual(void *qHandle, uint64_t qId);
 int64_t genQueryId(void);
 
+// util
+
+typedef struct {
+  int64_t qId;
+  int32_t timeMs;
+} SLongQuery;
+// return SArray* include SLongQuery*
+void* qObtainLongQuery(void* qMgmt, int32_t longMs);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/inc/taoserror.h b/src/inc/taoserror.h
index 368658377c..b04970e85d 100644
--- a/src/inc/taoserror.h
+++ b/src/inc/taoserror.h
@@ -35,6 +35,7 @@ int32_t* taosGetErrno();
 #define terrno                              (*taosGetErrno())
  
 #define TSDB_CODE_SUCCESS                   0
+#define TSDB_CODE_FAILED                    -1   // unknown or needn't tell detail error
 
 // rpc
 #define TSDB_CODE_RPC_ACTION_IN_PROGRESS        TAOS_DEF_ERROR_CODE(0, 0x0001)  //"Action in progress")
diff --git a/src/inc/tsdb.h b/src/inc/tsdb.h
index 7abe3e99c7..5e5ecc2438 100644
--- a/src/inc/tsdb.h
+++ b/src/inc/tsdb.h
@@ -192,6 +192,7 @@ typedef struct {
   SList *      bufBlockList;
   int64_t      pointsAdd;   // TODO
   int64_t      storageAdd;  // TODO
+  int64_t      commitedMs;  // commited ms time , zero is no commit.
 } SMemTable;
 
 typedef struct {
diff --git a/src/inc/vnode.h b/src/inc/vnode.h
index b3291645c0..2cc56af9de 100644
--- a/src/inc/vnode.h
+++ b/src/inc/vnode.h
@@ -88,6 +88,9 @@ int32_t vnodeWriteToRQueue(void *pVnode, void *pCont, int32_t contLen, int8_t qt
 void    vnodeFreeFromRQueue(void *pVnode, SVReadMsg *pRead);
 int32_t vnodeProcessRead(void *pVnode, SVReadMsg *pRead);
 
+// util
+void* vnodeGetqMgmt(void* pVnode);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/query/src/queryMain.c b/src/query/src/queryMain.c
index bb3f262c98..27680a7151 100644
--- a/src/query/src/queryMain.c
+++ b/src/query/src/queryMain.c
@@ -219,6 +219,9 @@ int32_t qCreateQueryInfo(void* tsdb, int32_t vgId, SQueryTableMsg* pQueryMsg, qi
 int waitMoment(SQInfo* pQInfo){
   if(pQInfo->sql) {
     int ms = 0;
+    char* pcnt = strstr(pQInfo->sql, " count(*)");
+    if(pcnt) return 0;
+    
     char* pos = strstr(pQInfo->sql, " t_");
     if(pos){
       pos += 3;
@@ -604,3 +607,87 @@ void** qReleaseQInfo(void* pMgmt, void* pQInfo, bool freeHandle) {
   taosCacheRelease(pQueryMgmt->qinfoPool, pQInfo, freeHandle);
   return 0;
 }
+
+//kill by qid
+int32_t qKillQueryByQId(void* pMgmt, int64_t qId, int32_t waitMs, int32_t waitCount) {
+  int32_t error = TSDB_CODE_SUCCESS;
+  void** handle = qAcquireQInfo(pMgmt, qId);
+  if(handle == NULL) return terrno;
+
+  SQInfo* pQInfo = (SQInfo*)(*handle);
+  if (pQInfo == NULL || !isValidQInfo(pQInfo)) {
+    return TSDB_CODE_QRY_INVALID_QHANDLE;
+  }
+
+  qDebug("QInfo:0x%"PRIx64" query killed by qid.", pQInfo->qId);
+  setQueryKilled(pQInfo);
+
+  // wait query stop
+  int32_t loop = 0;
+  while (pQInfo->owner != 0) {
+    taosMsleep(waitMs);
+    if(loop++ > waitCount){
+      error = TSDB_CODE_FAILED;
+      break;
+    }
+  }
+
+  return error;
+}
+
+int compareLongQuery(const void* p1, const void* p2) {
+  // sort desc 
+  SLongQuery* plq1 = (SLongQuery*)p1;
+  SLongQuery* plq2 = (SLongQuery*)p2;
+  if(plq1->timeMs == plq2->timeMs) {
+    return 0;
+  } else if(plq1->timeMs > plq2->timeMs) {
+    return -1;
+  } else {
+    return 1;
+  }
+}
+
+// util
+void* qObtainLongQuery(void* param, int32_t longMs){
+  SQueryMgmt* qMgmt =  (SQueryMgmt*)param;
+  if(qMgmt == NULL || qMgmt->qinfoPool == NULL) return NULL;
+  SArray* qids = taosArrayInit(4, sizeof(int64_t*));
+  
+  SHashObj* pHashTable = qMgmt->qinfoPool->pHashTable;
+  if(pHashTable == NULL || pHashTable->hashList == NULL) return NULL;
+
+  SQInfo * qInfo = (SQInfo*)taosHashIterate(pHashTable, NULL);
+  while(qInfo){
+    // judge long query
+    SMemTable* imem = qInfo->runtimeEnv.pQueryAttr->memRef.snapshot.imem;
+    if(imem == NULL || imem->commitedMs == 0) continue;
+    int64_t now = taosGetTimestampMs();
+    if(imem->commitedMs > now) continue; // weird, so skip
+
+    int32_t passMs = now - imem->commitedMs;
+    if(passMs < longMs) {
+      continue;
+    }
+
+    // push
+    SLongQuery* plq = (SLongQuery*)malloc(sizeof(SLongQuery));
+    plq->timeMs = passMs;
+    plq->qId = qInfo->qId;
+    taosArrayPush(qids, plq);
+
+    // next
+    qInfo = (SQInfo*)taosHashIterate(pHashTable, qInfo);
+  }
+
+  size_t cnt = taosArrayGetSize(qids);
+  if(cnt == 0) {
+    taosArrayDestroyEx(qids, free);
+    return NULL;
+  } 
+  if(cnt > 1) {
+    taosArraySort(qids, compareLongQuery);
+  }
+
+  return qids;   
+}
\ No newline at end of file
diff --git a/src/tsdb/inc/tsdbBuffer.h b/src/tsdb/inc/tsdbBuffer.h
index ec6b057aef..17919c284e 100644
--- a/src/tsdb/inc/tsdbBuffer.h
+++ b/src/tsdb/inc/tsdbBuffer.h
@@ -43,4 +43,8 @@ SListNode*    tsdbAllocBufBlockFromPool(STsdbRepo* pRepo);
 int           tsdbExpandPool(STsdbRepo* pRepo, int32_t oldTotalBlocks);
 void          tsdbRecycleBufferBlock(STsdbBufPool* pPool, SListNode *pNode);
 
+// health cite
+STsdbBufBlock *tsdbNewBufBlock(int bufBlockSize);
+void tsdbFreeBufBlock(STsdbBufBlock *pBufBlock);
+
 #endif /* _TD_TSDB_BUFFER_H_ */
diff --git a/src/tsdb/inc/tsdbHealth.h b/src/tsdb/inc/tsdbHealth.h
new file mode 100644
index 0000000000..9c48f552bb
--- /dev/null
+++ b/src/tsdb/inc/tsdbHealth.h
@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
+ *
+ * This program is free software: you can use, redistribute, and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3
+ * or later ("AGPL"), as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef _TD_TSDB_HEALTH_H_
+#define _TD_TSDB_HEALTH_H_
+
+bool tsdbUrgeQueryFree(STsdbRepo* pRepo);
+int32_t tsdbInsertNewBlock(STsdbRepo* pRepo);
+
+bool enoughIdleMemory();
+bool allowNewBlock(STsdbRepo* pRepo);
+
+#endif /* _TD_TSDB_BUFFER_H_ */
diff --git a/src/tsdb/src/tsdbBuffer.c b/src/tsdb/src/tsdbBuffer.c
index e675bf6f9d..a8d800208c 100644
--- a/src/tsdb/src/tsdbBuffer.c
+++ b/src/tsdb/src/tsdbBuffer.c
@@ -14,12 +14,10 @@
  */
 
 #include "tsdbint.h"
+#include "tsdbHealth.h"
 
 #define POOL_IS_EMPTY(b) (listNEles((b)->bufBlockList) == 0)
 
-static STsdbBufBlock *tsdbNewBufBlock(int bufBlockSize);
-static void           tsdbFreeBufBlock(STsdbBufBlock *pBufBlock);
-
 // ---------------- INTERNAL FUNCTIONS ----------------
 STsdbBufPool *tsdbNewBufPool() {
   STsdbBufPool *pBufPool = (STsdbBufPool *)calloc(1, sizeof(*pBufPool));
@@ -120,6 +118,14 @@ SListNode *tsdbAllocBufBlockFromPool(STsdbRepo *pRepo) {
   STsdbBufPool *pBufPool = pRepo->pPool;
 
   while (POOL_IS_EMPTY(pBufPool)) {
+    // supply new Block 
+    if(tsdbInsertNewBlock(pRepo) > 0) {
+      break;
+    } else {
+      // no newBlock, kill query free
+      tsdbUrgeQueryFree(pRepo);
+    }
+
     pRepo->repoLocked = false;
     pthread_cond_wait(&(pBufPool->poolNotEmpty), &(pRepo->mutex));
     pRepo->repoLocked = true;
@@ -139,7 +145,7 @@ SListNode *tsdbAllocBufBlockFromPool(STsdbRepo *pRepo) {
 }
 
 // ---------------- LOCAL FUNCTIONS ----------------
-static STsdbBufBlock *tsdbNewBufBlock(int bufBlockSize) {
+STsdbBufBlock *tsdbNewBufBlock(int bufBlockSize) {
   STsdbBufBlock *pBufBlock = (STsdbBufBlock *)malloc(sizeof(*pBufBlock) + bufBlockSize);
   if (pBufBlock == NULL) {
     terrno = TSDB_CODE_TDB_OUT_OF_MEMORY;
@@ -157,7 +163,7 @@ _err:
   return NULL;
 }
 
-static void tsdbFreeBufBlock(STsdbBufBlock *pBufBlock) { tfree(pBufBlock); }
+ void tsdbFreeBufBlock(STsdbBufBlock *pBufBlock) { tfree(pBufBlock); }
 
 int tsdbExpandPool(STsdbRepo* pRepo, int32_t oldTotalBlocks) {
   if (oldTotalBlocks == pRepo->config.totalBlocks) {
@@ -199,4 +205,4 @@ void tsdbRecycleBufferBlock(STsdbBufPool* pPool, SListNode *pNode) {
   tsdbFreeBufBlock(pBufBlock);
   free(pNode);
   pPool->nBufBlocks--;
-}
+}
\ No newline at end of file
diff --git a/src/tsdb/src/tsdbCommit.c b/src/tsdb/src/tsdbCommit.c
index 8f5f885d69..6fae5c6555 100644
--- a/src/tsdb/src/tsdbCommit.c
+++ b/src/tsdb/src/tsdbCommit.c
@@ -547,6 +547,8 @@ static void tsdbEndCommit(STsdbRepo *pRepo, int eno) {
   (void)tsdbLockRepo(pRepo);
   pRepo->imem = NULL;
   (void)tsdbUnlockRepo(pRepo);
+  //save commited time
+  pIMem->commitedMs = taosGetTimestampMs();
   tsdbUnRefMemTable(pRepo, pIMem);
   tsem_post(&(pRepo->readyToCommit));
 }
diff --git a/src/tsdb/src/tsdbHealth.c b/src/tsdb/src/tsdbHealth.c
new file mode 100644
index 0000000000..7cd6672e93
--- /dev/null
+++ b/src/tsdb/src/tsdbHealth.c
@@ -0,0 +1,132 @@
+/*
+ * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
+ *
+ * This program is free software: you can use, redistribute, and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3
+ * or later ("AGPL"), as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "os.h"
+#include "taosmsg.h"
+#include "tarray.h"
+#include "query.h"
+#include "tglobal.h"
+#include "tsdbint.h"
+#include "tsdbBuffer.h"
+#include "tsdbLog.h"
+#include "tsdbHealth.h"
+#include "tsdbint.h"
+#include "ttimer.h"
+#include "vnode.h"
+
+
+// return malloc new block count 
+int32_t tsdbInsertNewBlock(STsdbRepo * pRepo) {
+  STsdbBufPool *pPool = pRepo->pPool;
+  int32_t cnt = 0;
+
+  if(enoughIdleMemory() && allowNewBlock(pRepo)) {
+    STsdbBufBlock *pBufBlock = tsdbNewBufBlock(pPool->bufBlockSize);
+    if (pBufBlock) {
+      if (tsdbLockRepo(pRepo) >= 0) {
+        if (tdListAppend(pPool->bufBlockList, (void *)(&pBufBlock)) < 0) {
+          // append error
+          tsdbFreeBufBlock(pBufBlock);
+        } else {
+          pPool->nRecycleBlocks ++;
+          cnt ++ ; 
+        }
+        tsdbUnlockRepo(pRepo);  
+      }
+    }
+ } 
+ return cnt;
+}
+
+// switch anther thread to run
+void cbKillQueryFree(void* param1, void* param2) {
+  STsdbRepo* pRepo =  (STsdbRepo*)param1;
+  int32_t longMs = 2000; // TODO config to taos.cfg
+  
+  // vnode
+  void* vnodeObj = pRepo->appH.appH;
+  if(vnodeObj == NULL) return ;
+
+  // qMgmt
+  void* qMgmt = vnodeGetqMgmt(vnodeObj);
+  if(qMgmt == NULL) return ;
+
+  // qid top list
+  SArray *qids = (SArray*)qObtainLongQuery(qMgmt, longMs);
+  if(qids == NULL) return ;
+
+  // kill Query
+  size_t cnt = taosArrayGetSize(qids);
+  int64_t qId = 0;
+  for(size_t i=0; i < cnt; i++) {
+    qId = *(int64_t*)taosArrayGetP(qids, i);
+    qKillQueryByQId(qMgmt, qId, 100, 50); // wait 50*100 ms 
+    // notify wait
+    pthread_cond_signal(&pRepo->pPool->poolNotEmpty);
+    // check break condition 
+    if(enoughIdleMemory() && allowNewBlock(pRepo)) {
+      break;
+    }
+  }
+
+  // free qids
+  taosArrayDestroyEx(qids, free);
+}
+
+// return true do free , false do nothing
+bool tsdbUrgeQueryFree(STsdbRepo * pRepo) {
+  // 1 start timer
+  tmr_h hTimer = taosTmrStart(cbKillQueryFree, 1, pRepo, NULL);
+  return hTimer != NULL;
+}
+
+bool enoughIdleMemory(){
+  // TODO config to taos.cfg
+  int32_t lowestRate = 20;  // below 20% idle memory, return not enough memory
+  float  memoryUsedMB = 0;
+  float  memoryAvailMB;
+
+  if (true != taosGetSysMemory(&memoryUsedMB)) {
+    tsdbWarn("tsdbHealth get memory error, return false.");
+    return false;
+  }
+
+  if(memoryUsedMB > tsTotalMemoryMB || tsTotalMemoryMB == 0) {
+    tsdbWarn("tsdbHealth used memory(%d MB) large total memory(%d MB), return false.", (int)memoryUsedMB, (int)tsTotalMemoryMB);
+    return false;
+  }
+
+  memoryAvailMB = (float)tsTotalMemoryMB - memoryUsedMB;
+  int32_t rate = (int32_t)(memoryAvailMB/tsTotalMemoryMB * 100);
+  if(rate < lowestRate){
+    tsdbWarn("tsdbHealth real rate :%d less than lowest rate:%d, so return false.", rate, lowestRate);
+    return false;
+  }
+
+  return true;
+}
+
+bool allowNewBlock(STsdbRepo* pRepo){
+  //TODO config to taos.cfg
+  int32_t nElasticBlocks = 10;
+  STsdbBufPool* pPool = pRepo->pPool;
+  int32_t nOverBlocks = pPool->nBufBlocks - pRepo->config.totalBlocks;
+  if(nOverBlocks > nElasticBlocks) {
+    tsdbWarn("tsdbHealth allowNewBlock forbid. nOverBlocks(%d) > nElasticBlocks(%d)", nOverBlocks, nElasticBlocks);
+    return false;
+  }
+
+  return true;
+}
diff --git a/src/vnode/src/vnodeMain.c b/src/vnode/src/vnodeMain.c
index f826c1aecd..7802d2a081 100644
--- a/src/vnode/src/vnodeMain.c
+++ b/src/vnode/src/vnodeMain.c
@@ -562,3 +562,9 @@ static int32_t vnodeProcessTsdbStatus(void *arg, int32_t status, int32_t eno) {
 
   return 0;
 }
+
+// get qmgmt
+void* vnodeGetqMgmt(void* pVnode){
+  if(pVnode == NULL) return NULL;
+  return ((SVnodeObj*)pVnode)->qMgmt;
+}