diff --git a/internal/util/chutil.go b/internal/util/chutil.go
index 96508c3b4..dc84b152b 100644
--- a/internal/util/chutil.go
+++ b/internal/util/chutil.go
@@ -163,6 +163,7 @@ func (ch *ClickHouse) Select(ctx context.Context, meta QueryMetaInto, query ch.Q
 	kind := QueryKind(meta.IsFast, meta.IsLight)
 	pool := ch.pools[kind]
 	servers := append(make([]*chpool.Pool, 0, len(pool.servers)), pool.servers...)
+	// TODO add metric
 	for safetyCounter := 0; safetyCounter < len(pool.servers); safetyCounter++ {
 		var i int
 		i, err = pickRandomServer(servers, pool.rnd)
@@ -177,39 +178,49 @@ func (ch *ClickHouse) Select(ctx context.Context, meta QueryMetaInto, query ch.Q
 		statshouse.Metric("statshouse_unique_wait_test", statshouse.Tags{1: strconv.FormatInt(int64(kind), 10), 2: "uniq"}).Value(float64(uniqWait))
 		statshouse.Metric("statshouse_unique_wait_test", statshouse.Tags{1: strconv.FormatInt(int64(kind), 10), 2: "all"}).Value(float64(allWait))
 		pool.waitMx.Unlock()
-		err = pool.sem.Acquire(ctx, meta.User)
-		waitLockDuration := time.Since(startTime)
-		pool.waitMx.Lock()
-		pool.userWait[meta.User]--
-		if c := pool.userWait[meta.User]; c == 0 {
-			delete(pool.userWait, meta.User)
-		}
-		pool.waitMx.Unlock()
-		statshouse.Metric("statshouse_wait_lock", statshouse.Tags{1: strconv.FormatInt(int64(kind), 10), 2: meta.User}).Value(waitLockDuration.Seconds())
-		if err != nil {
-			return info, err
-		}
-		pool.mx.Lock()
-		pool.userActive[meta.User]++
-		uniq := len(pool.userActive)
-		all := pool.countOfReqLocked(pool.userActive)
-		pool.mx.Unlock()
-		statshouse.Metric("statshouse_unique_test", statshouse.Tags{1: strconv.FormatInt(int64(kind), 10), 2: "uniq"}).Value(float64(uniq))
-		statshouse.Metric("statshouse_unique_test", statshouse.Tags{1: strconv.FormatInt(int64(kind), 10), 2: "all"}).Value(float64(all))
-
-		start := time.Now()
-		err = servers[i].Do(ctx, query)
-		info.Duration = time.Since(start)
-		pool.mx.Lock()
-		pool.userActive[meta.User]--
-		if c := pool.userActive[meta.User]; c == 0 {
-			delete(pool.userActive, meta.User)
-		}
-		pool.mx.Unlock()
-		pool.sem.Release()
+		mustRetry := false
+		err = func() error {
+			err := pool.sem.Acquire(ctx, meta.User)
+			waitLockDuration := time.Since(startTime)
+			pool.waitMx.Lock()
+			pool.userWait[meta.User]--
+			if c := pool.userWait[meta.User]; c == 0 {
+				delete(pool.userWait, meta.User)
+			}
+			pool.waitMx.Unlock()
+			statshouse.Metric("statshouse_wait_lock", statshouse.Tags{1: strconv.FormatInt(int64(kind), 10), 2: meta.User}).Value(waitLockDuration.Seconds())
+			if err != nil {
+				return err
+			}
+			defer pool.sem.Release()
+			pool.mx.Lock()
+			pool.userActive[meta.User]++
+			uniq := len(pool.userActive)
+			all := pool.countOfReqLocked(pool.userActive)
+			pool.mx.Unlock()
+			statshouse.Metric("statshouse_unique_test", statshouse.Tags{1: strconv.FormatInt(int64(kind), 10), 2: "uniq"}).Value(float64(uniq))
+			statshouse.Metric("statshouse_unique_test", statshouse.Tags{1: strconv.FormatInt(int64(kind), 10), 2: "all"}).Value(float64(all))
+
+			start := time.Now()
+			err = servers[i].Do(ctx, query)
+			info.Duration = time.Since(start)
+			pool.mx.Lock()
+			pool.userActive[meta.User]--
+			if c := pool.userActive[meta.User]; c == 0 {
+				delete(pool.userActive, meta.User)
+			}
+			pool.mx.Unlock()
+			if err != nil {
+				mustRetry = true
+			}
+			return err
+		}()
 		if err == nil {
 			return // succeeded
 		}
+		if err != nil && !mustRetry {
+			return info, err
+		}
 		if ctx.Err() != nil {
 			return // failed
 		}