diff --git a/docs/cn/rpcz.md b/docs/cn/rpcz.md
index b2808da268..637997d15f 100644
--- a/docs/cn/rpcz.md
+++ b/docs/cn/rpcz.md
@@ -13,6 +13,7 @@
 | rpcz_database_dir          | ./rpc_data/rpcz      | For storing requests/contexts collected by rpcz. | src/baidu/rpc/span.cpp                 |
 | rpcz_keep_span_db          | false                | Don't remove DB of rpcz at program's exit | src/baidu/rpc/span.cpp                 |
 | rpcz_keep_span_seconds (R) | 3600                 | Keep spans for at most so many seconds   | src/baidu/rpc/span.cpp                 |
+| rpcz_save_span_min_latency_us (R) | 0 (default:0) | The minimum latency microseconds of span saved | src/baidu/rpc/span.cpp |
 
 若启动时未加-enable_rpcz，则可在启动后访问SERVER_URL/rpcz/enable动态开启rpcz，访问SERVER_URL/rpcz/disable则关闭，这两个链接等价于访问SERVER_URL/flags/enable_rpcz?setvalue=true和SERVER_URL/flags/enable_rpcz?setvalue=false。在r31010之后，rpc在html版本中增加了一个按钮可视化地开启和关闭。
 
diff --git a/src/brpc/span.cpp b/src/brpc/span.cpp
index 356a7cd039..7a0218ddc1 100644
--- a/src/brpc/span.cpp
+++ b/src/brpc/span.cpp
@@ -29,6 +29,7 @@
 #include "butil/object_pool.h"
 #include "butil/fast_rand.h"
 #include "butil/file_util.h"
+#include "butil/files/file_enumerator.h"
 #include "brpc/shared_object.h"
 #include "brpc/reloadable_flags.h"
 #include "brpc/span.h"
@@ -59,6 +60,9 @@ BRPC_VALIDATE_GFLAG(rpcz_keep_span_seconds, PositiveInteger);
 
 DEFINE_bool(rpcz_keep_span_db, false, "Don't remove DB of rpcz at program's exit");
 
+DEFINE_int64(rpcz_save_span_min_latency_us, 0, "The minimum latency microseconds of span saved");
+BRPC_VALIDATE_GFLAG(rpcz_save_span_min_latency_us, NonNegativeInteger);
+
 struct IdGen {
     bool init;
     uint16_t seq;
@@ -378,10 +382,8 @@ class SpanDB : public SharedObject {
         delete id_db;
         delete time_db;
         if (!FLAGS_rpcz_keep_span_db) {
-            std::string cmd = butil::string_printf("rm -rf %s %s",
-                                                  id_db_name.c_str(),
-                                                  time_db_name.c_str());
-            butil::ignore_result(system(cmd.c_str()));
+            butil::DeleteFile(butil::FilePath(id_db_name), true);
+            butil::DeleteFile(butil::FilePath(time_db_name), true);
         }
     }
 };
@@ -506,6 +508,15 @@ inline uint64_t ToLittleEndian(const uint32_t* buf) {
 }
 
 SpanDB* SpanDB::Open() {
+    // Remove old rpcz directory even if crash occurs.
+    if (!FLAGS_rpcz_keep_span_db) {
+        butil::FileEnumerator dirs(butil::FilePath(FLAGS_rpcz_database_dir), false,
+                                   butil::FileEnumerator::DIRECTORIES, "[0-9]*.[0-9]*.[0-9]*");
+        for (auto name = dirs.Next(); !name.empty(); name = dirs.Next()) {
+            butil::DeleteFile(name, true);
+        }
+    }
+
     SpanDB local;
     leveldb::Status st;
     char prefix[64];
@@ -568,6 +579,11 @@ leveldb::Status SpanDB::Index(const Span* span, std::string* value_buf) {
     // of time window.
 
     const int64_t start_time = span->GetStartRealTimeUs();
+    const int64_t latency_us = span->GetEndRealTimeUs() - start_time;
+    // if latency_us < FLAGS_rpcz_save_span_min_latency_us, don't save this span
+    if (latency_us < FLAGS_rpcz_save_span_min_latency_us) {
+        return leveldb::Status::OK();
+    }
     BriefSpan brief;
     brief.set_trace_id(span->trace_id());
     brief.set_span_id(span->span_id());
@@ -577,7 +593,7 @@ leveldb::Status SpanDB::Index(const Span* span, std::string* value_buf) {
     brief.set_request_size(span->request_size());
     brief.set_response_size(span->response_size());
     brief.set_start_real_us(start_time);
-    brief.set_latency_us(span->GetEndRealTimeUs() - start_time);
+    brief.set_latency_us(latency_us);
     brief.set_full_method_name(span->full_method_name());
     if (!brief.SerializeToString(value_buf)) {
         return leveldb::Status::InvalidArgument(