diff --git a/Cargo.toml b/Cargo.toml
index c67cb96..d5a492a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -4,7 +4,7 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
-mace-kv = "0.0.25"
+mace-kv = "0.0.27"
 clap = { version = "4.5.48", features = ["derive"] }
 rand = "0.9.2"
 log = "0.4.22"
diff --git a/README.md b/README.md
index 0d6598b..43c5ec7 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,4 @@
-# mace 0.0.24 vs rocksdb 10.4.2
-
-**mace 0.0.24 traded a slight dip in query performance for a 10+% boost in insertion performance.**
+# mace 0.0.27 vs rocksdb 10.4.2
 
 ## sequential insert
 ![mace_sequential_insert](./scripts/mace_sequential_insert.png)
diff --git a/rocksdb/main.cpp b/rocksdb/main.cpp
index 01f2ca6..b683aa9 100644
--- a/rocksdb/main.cpp
+++ b/rocksdb/main.cpp
@@ -22,6 +22,10 @@
 #include <format>
 #include <string>
 
+#include <pthread.h>
+#include <sched.h>
+#include <unistd.h>
+
 #include "CLI/CLI.hpp"
 #include "instant.h"
 
@@ -30,6 +34,19 @@ static void black_box(const T &t) {
     asm volatile("" ::"m"(t) : "memory");
 }
 
+static size_t cores_online() {
+    auto n = ::sysconf(_SC_NPROCESSORS_ONLN);
+    return n > 0 ? static_cast<size_t>(n) : 1;
+}
+
+static void bind_core(size_t tid) {
+    cpu_set_t set;
+    CPU_ZERO(&set);
+    auto core = static_cast<int>(tid % cores_online());
+    CPU_SET(core, &set);
+    (void) pthread_setaffinity_np(pthread_self(), sizeof(cpu_set_t), &set);
+}
+
 struct Args {
     size_t threads;
     size_t iterations;
@@ -59,11 +76,11 @@ int main(int argc, char *argv[]) {
     app.add_option("-t,--threads", args.threads, "Threads");
     app.add_option("-k,--key-size", args.key_size, "Key Size");
     app.add_option("-v,--value-size", args.value_size, "Value Size");
-    app.add_option("-b,--blob-size", args.value_size, "Blob Size");
+    app.add_option("-b,--blob-size", args.blob_size, "Blob Size");
     app.add_option("-i,--iterations", args.iterations, "Iterations");
     app.add_option("-r,--insert-ratio", args.insert_ratio, "Insert Ratio for mixed mode");
     app.add_option("-p,--path", args.path, "DataBase Home");
-    app.add_option("--random", args.random, "Shuffle insert keys");
+    app.add_flag("--random", args.random, "Shuffle insert keys");
 
     CLI11_PARSE(app, argc, argv);
 
@@ -77,6 +94,11 @@ int main(int argc, char *argv[]) {
         return 1;
     }
 
+    if (args.threads == 0) {
+        fmt::println("Error: threads must be greater than 0");
+        return 1;
+    }
+
     if (args.mode != "insert" && args.mode != "get" && args.mode != "mixed" && args.mode != "scan") {
         fmt::println("Error: Invalid mode");
         return 1;
@@ -142,27 +164,31 @@ int main(int argc, char *argv[]) {
     std::atomic<uint64_t> total_op{0};
     rocksdb::OptimisticTransactionDB *db;
     auto b = nm::Instant::now();
-    std::mutex mtx{};
     std::vector<rocksdb::ColumnFamilyHandle *> handles{};
     auto s = rocksdb::OptimisticTransactionDB::Open(options, args.path, cfd, &handles, &db);
     assert(s.ok());
-    std::barrier barrier{static_cast<ptrdiff_t>(args.threads)};
+    std::barrier ready_barrier{static_cast<ptrdiff_t>(args.threads + 1)};
+    std::barrier start_barrier{static_cast<ptrdiff_t>(args.threads + 1)};
 
     std::random_device rd{};
     std::mt19937 gen(rd());
-    std::uniform_int_distribution<int> dist(0, 100);
 
     std::string val(args.value_size, 'x');
-    auto keys_per_thread = args.iterations / args.threads;
+    std::vector<size_t> key_counts(args.threads, args.iterations / args.threads);
+    for (size_t i = 0; i < args.iterations % args.threads; ++i) {
+        key_counts[i] += 1;
+    }
+    keys.reserve(args.threads);
     for (size_t tid = 0; tid < args.threads; ++tid) {
         std::vector<std::string> key{};
-        for (size_t i = 0; i < keys_per_thread; ++i) {
+        key.reserve(key_counts[tid]);
+        for (size_t i = 0; i < key_counts[tid]; ++i) {
             auto tmp = std::format("key_{}_{}", tid, i);
             tmp.resize(args.key_size, 'x');
             key.emplace_back(std::move(tmp));
         }
         if (args.mode == "get" || args.random) {
-            std::shuffle(keys.begin(), keys.end(), gen);
+            std::shuffle(key.begin(), key.end(), gen);
         }
         keys.emplace_back(std::move(key));
     }
@@ -189,11 +215,14 @@ int main(int argc, char *argv[]) {
         handle = handles[0];
 
         // simulate common use cases
-        std::uniform_int_distribution<int> dist(0, args.threads - 1);
-        for (size_t i = 0; i < keys_per_thread; ++i) {
-            auto tid = dist(gen);
-            auto k = std::format("key_{}_{}", tid, i);
-            k.resize(args.key_size, 'x');
+        std::uniform_int_distribution<size_t> tid_dist(0, args.threads - 1);
+        for (size_t i = 0; i < args.iterations; ++i) {
+            auto tid = tid_dist(gen);
+            if (keys[tid].empty()) {
+                continue;
+            }
+            std::uniform_int_distribution<size_t> key_dist(0, keys[tid].size() - 1);
+            const auto &k = keys[tid][key_dist(gen)];
             auto s = db->Get(rocksdb::ReadOptions(), k, &val);
             if (!s.ok()) {
                 std::terminate();
@@ -202,10 +231,12 @@ int main(int argc, char *argv[]) {
     }
 
     auto *snapshot = db->GetSnapshot();
+    auto base_seed = rd();
     for (size_t tid = 0; tid < args.threads; ++tid) {
         wg.emplace_back([&, tid] {
+            bind_core(tid);
             std::string rval(args.value_size, '0');
-            auto prefix = std::format("key_{}", tid);
+            auto prefix = std::format("key_{}_", tid);
             auto ropt = rocksdb::ReadOptions();
             auto upper_bound = find_upper_bound(prefix);
             auto upper_bound_slice = rocksdb::Slice(upper_bound);
@@ -216,12 +247,11 @@ int main(int argc, char *argv[]) {
             ropt.prefix_same_as_start = true;
             ropt.snapshot = snapshot;
             size_t round = 0;
+            std::mt19937 mixed_gen(static_cast<uint32_t>(base_seed) ^ static_cast<uint32_t>(0x9e3779b9U * (tid + 1)));
+            std::uniform_int_distribution<int> mixed_dist(0, 99);
 
-            barrier.arrive_and_wait();
-            if (mtx.try_lock()) {
-                b = nm::Instant::now();
-                mtx.unlock();
-            }
+            ready_barrier.arrive_and_wait();
+            start_barrier.arrive_and_wait();
 
             if (args.mode == "insert") {
                 for (auto &key: *tk) {
@@ -243,7 +273,7 @@ int main(int argc, char *argv[]) {
             } else if (args.mode == "mixed") {
                 for (auto &key: *tk) {
                     round += 1;
-                    auto is_insert = dist(gen) < args.insert_ratio;
+                    auto is_insert = mixed_dist(mixed_gen) < static_cast<int>(args.insert_ratio);
                     auto *kv = db->BeginTransaction(wopt);
                     if (is_insert) {
                         kv->Put(handle, key, val);
@@ -273,6 +303,10 @@ int main(int argc, char *argv[]) {
         });
     }
 
+    ready_barrier.arrive_and_wait();
+    b = nm::Instant::now();
+    start_barrier.arrive_and_wait();
+
     for (auto &w: wg) {
         w.join();
     }
diff --git a/scripts/mace.sh b/scripts/mace.sh
index 6cb0a8c..07b4d19 100755
--- a/scripts/mace.sh
+++ b/scripts/mace.sh
@@ -1,21 +1,24 @@
 #!/usr/bin/env bash
 
+set -euo pipefail
+
 if [ "$#" -ne 1 ]
 then
     printf "\033[m$0 path\033[0m\n"
     exit 1
 fi
 
-pushd .
-cd ..
-cargo build --release 1>/dev/null 2> /dev/null
+script_dir="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
+root_dir="$(cd -- "${script_dir}/.." && pwd)"
+
+cargo build --release --manifest-path "${root_dir}/Cargo.toml" 1>/dev/null 2>/dev/null
 
 function samples() {
         export RUST_BACKTRACE=full
         kv_sz=(16 16 100 1024 1024 1024 16 10240)
         mode=(insert get mixed scan)
         # set -x
-        db_root=$1
+        db_root="$1"
 
         cnt=100000
         for ((i = 1; i <= $(nproc); i *= 2))
@@ -26,14 +29,14 @@ function samples() {
                       do 
                             if [ "${mode[k]}" == "insert" ]
                             then
-                                  ./target/release/kv_bench --path $db_root --threads $i --iterations $cnt --mode ${mode[k]} --key-size ${kv_sz[j]} --value-size ${kv_sz[j+1]} --random
+                                  "${root_dir}/target/release/kv_bench" --path "${db_root}" --threads "${i}" --iterations "${cnt}" --mode "${mode[k]}" --key-size "${kv_sz[j]}" --value-size "${kv_sz[j+1]}" --random
                                   if test $? -ne 0
                                   then
                                           echo "${mode[k]} threads $i ksz ${kv_sz[j]} vsz ${kv_sz[j+1]} random fail"
                                           exit 1
                                   fi
                             fi
-                            ./target/release/kv_bench --path $db_root --threads $i --iterations $cnt --mode ${mode[k]} --key-size ${kv_sz[j]} --value-size ${kv_sz[j+1]}
+                            "${root_dir}/target/release/kv_bench" --path "${db_root}" --threads "${i}" --iterations "${cnt}" --mode "${mode[k]}" --key-size "${kv_sz[j]}" --value-size "${kv_sz[j+1]}"
                             if test $? -ne 0
                             then
                                     echo "${mode[k]} threads $i ksz ${kv_sz[j]} vsz ${kv_sz[j+1]} fail"
@@ -44,7 +47,10 @@ function samples() {
         done
 }
 
-echo mode,threads,key_size,value_size,insert_ratio,ops,elasped > scripts/mace.csv
-samples $1 2>> scripts/mace.csv
-popd
-./bin/python plot.py mace.csv
+echo mode,threads,key_size,value_size,insert_ratio,ops,elasped > "${script_dir}/mace.csv"
+samples "$1" 2>> "${script_dir}/mace.csv"
+if [ -x "${script_dir}/bin/python" ]; then
+    (cd "${script_dir}" && "${script_dir}/bin/python" plot.py mace.csv)
+else
+    (cd "${script_dir}" && python3 plot.py mace.csv)
+fi
diff --git a/scripts/mace_get.png b/scripts/mace_get.png
index 4348333..20c409b 100644
Binary files a/scripts/mace_get.png and b/scripts/mace_get.png differ
diff --git a/scripts/mace_mixed.png b/scripts/mace_mixed.png
index f609baa..e3bad3e 100644
Binary files a/scripts/mace_mixed.png and b/scripts/mace_mixed.png differ
diff --git a/scripts/mace_random_insert.png b/scripts/mace_random_insert.png
index e82473d..9ef9fa6 100644
Binary files a/scripts/mace_random_insert.png and b/scripts/mace_random_insert.png differ
diff --git a/scripts/mace_scan.png b/scripts/mace_scan.png
index 877c962..914e631 100644
Binary files a/scripts/mace_scan.png and b/scripts/mace_scan.png differ
diff --git a/scripts/mace_sequential_insert.png b/scripts/mace_sequential_insert.png
index 63bdc84..158e0bf 100644
Binary files a/scripts/mace_sequential_insert.png and b/scripts/mace_sequential_insert.png differ
diff --git a/scripts/rocksdb.sh b/scripts/rocksdb.sh
index fb3031a..068fc13 100755
--- a/scripts/rocksdb.sh
+++ b/scripts/rocksdb.sh
@@ -1,21 +1,25 @@
 #!/usr/bin/env bash
 
+set -euo pipefail
+
 if [ "$#" -ne 1 ]
 then
   printf "\033[m$0 path\033[0m\n"
   exit 1
 fi
 
-pushd .
-cd ../rocksdb
-cmake --preset release 1>/dev/null 2>/dev/null
-cmake --build --preset release 1>/dev/null 2>/dev/null
+script_dir="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
+root_dir="$(cd -- "${script_dir}/.." && pwd)"
+rocksdb_dir="${root_dir}/rocksdb"
+
+(cd "${rocksdb_dir}" && cmake --preset release 1>/dev/null 2>/dev/null)
+(cd "${rocksdb_dir}" && cmake --build --preset release 1>/dev/null 2>/dev/null)
 
 function samples() {
         kv_sz=(16 16 100 1024 1024 1024 16 10240)
         mode=(insert get mixed scan)
         # set -x
-        db_root=$1
+        db_root="$1"
         cnt=100000
         for ((i = 1; i <= $(nproc); i *= 2))
         do
@@ -25,14 +29,14 @@ function samples() {
                         do
                             if [ "${mode[k]}" == "insert" ]
                             then
-                                ./build/release/rocksdb_bench --path $db_root --threads $i --iterations $cnt --mode ${mode[k]} --key-size ${kv_sz[j]} --value-size ${kv_sz[j+1]} --random 1
+                                "${rocksdb_dir}/build/release/rocksdb_bench" --path "${db_root}" --threads "${i}" --iterations "${cnt}" --mode "${mode[k]}" --key-size "${kv_sz[j]}" --value-size "${kv_sz[j+1]}" --random
                                 if test $? -ne 0
                                 then
                                         echo "${mode[k]} threads $i ksz ${kv_sz[j]} vsz ${kv_sz[j+1]} random fail"
                                         exit 1
                                 fi
                             fi
-                            ./build/release/rocksdb_bench --path $db_root --threads $i --iterations $cnt --mode ${mode[k]} --key-size ${kv_sz[j]} --value-size ${kv_sz[j+1]}
+                            "${rocksdb_dir}/build/release/rocksdb_bench" --path "${db_root}" --threads "${i}" --iterations "${cnt}" --mode "${mode[k]}" --key-size "${kv_sz[j]}" --value-size "${kv_sz[j+1]}"
                             if test $? -ne 0
                             then
                                     echo "${mode[k]} threads $i ksz ${kv_sz[j]} vsz ${kv_sz[j+1]} fail"
@@ -43,7 +47,10 @@ function samples() {
         done
 }
 
-echo mode,threads,key_size,value_size,insert_ratio,ops,elapsed > ../scripts/rocksdb.csv
-samples $1 1>> ../scripts/rocksdb.csv
-popd
-./bin/python plot.py rocksdb.csv
+echo mode,threads,key_size,value_size,insert_ratio,ops,elapsed > "${script_dir}/rocksdb.csv"
+samples "$1" 1>> "${script_dir}/rocksdb.csv"
+if [ -x "${script_dir}/bin/python" ]; then
+    (cd "${script_dir}" && "${script_dir}/bin/python" plot.py rocksdb.csv)
+else
+    (cd "${script_dir}" && python3 plot.py rocksdb.csv)
+fi
diff --git a/scripts/rocksdb_get.png b/scripts/rocksdb_get.png
index 63efa0d..24a886b 100644
Binary files a/scripts/rocksdb_get.png and b/scripts/rocksdb_get.png differ
diff --git a/scripts/rocksdb_mixed.png b/scripts/rocksdb_mixed.png
index 296b2f9..006477d 100644
Binary files a/scripts/rocksdb_mixed.png and b/scripts/rocksdb_mixed.png differ
diff --git a/scripts/rocksdb_random_insert.png b/scripts/rocksdb_random_insert.png
index c76af41..31c1cd5 100644
Binary files a/scripts/rocksdb_random_insert.png and b/scripts/rocksdb_random_insert.png differ
diff --git a/scripts/rocksdb_scan.png b/scripts/rocksdb_scan.png
index eeaf557..7ce38cf 100644
Binary files a/scripts/rocksdb_scan.png and b/scripts/rocksdb_scan.png differ
diff --git a/scripts/rocksdb_sequential_insert.png b/scripts/rocksdb_sequential_insert.png
index 4933dc9..eed3970 100644
Binary files a/scripts/rocksdb_sequential_insert.png and b/scripts/rocksdb_sequential_insert.png differ
diff --git a/src/main.rs b/src/main.rs
index 9f881ab..8c66ed5 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -66,6 +66,16 @@ fn main() {
         exit(1);
     }
 
+    if args.threads == 0 {
+        eprintln!("Error: threads must be greater than 0");
+        exit(1);
+    }
+
+    if !matches!(args.mode.as_str(), "insert" | "get" | "mixed" | "scan") {
+        eprintln!("Error: Invalid mode");
+        exit(1);
+    }
+
     if args.key_size < 16 || args.value_size < 16 {
         eprintln!("Error: key_size or value_size too small, must >= 16");
         exit(1);
@@ -87,13 +97,17 @@ fn main() {
     saved.tmp_store = false;
     let mut db = Mace::new(opt.validate().unwrap()).unwrap();
     db.disable_gc();
+    let mut bkt = db.new_bucket("default").unwrap();
 
     let mut rng = rand::rng();
     let value = Arc::new(vec![b'0'; args.value_size]);
-    let keys_per_thread = args.iterations / args.threads;
+    let mut key_counts = vec![args.iterations / args.threads; args.threads];
+    for cnt in key_counts.iter_mut().take(args.iterations % args.threads) {
+        *cnt += 1;
+    }
     for tid in 0..args.threads {
-        let mut tk = Vec::with_capacity(keys_per_thread);
-        for i in 0..keys_per_thread {
+        let mut tk = Vec::with_capacity(key_counts[tid]);
+        for i in 0..key_counts[tid] {
             let mut key = format!("key_{tid}_{i}").into_bytes();
             key.resize(args.key_size, b'x');
             tk.push(key);
@@ -105,54 +119,52 @@ fn main() {
     }
 
     if args.mode == "get" || args.mode == "scan" {
-        let pre_tx = db.begin().unwrap();
+        let pre_tx = bkt.begin().unwrap();
         (0..args.threads).for_each(|tid| {
             for k in &keys[tid] {
                 pre_tx.put(k, &*value).unwrap();
             }
         });
         pre_tx.commit().unwrap();
+        drop(bkt);
         drop(db);
         // re-open db
         saved.tmp_store = true;
         db = Mace::new(saved.validate().unwrap()).unwrap();
+        bkt = db.get_bucket("default").unwrap();
 
         // simulate common use cases
-        for i in 0..keys_per_thread {
+        for _ in 0..args.iterations {
             let tid = rng.random_range(0..args.threads);
-            let mut k = format!("key_{tid}_{i}").into_bytes();
-            k.resize(args.key_size, b'x');
-            let view = db.view().unwrap();
-            view.get(&k).unwrap();
+            let Some(k) = keys[tid].choose(&mut rng) else {
+                continue;
+            };
+            let view = bkt.view().unwrap();
+            view.get(k).unwrap();
         }
     }
 
-    let barrier = Arc::new(std::sync::Barrier::new(args.threads));
+    let ready_barrier = Arc::new(std::sync::Barrier::new(args.threads + 1));
+    let start_barrier = Arc::new(std::sync::Barrier::new(args.threads + 1));
     let total_ops = Arc::new(std::sync::atomic::AtomicUsize::new(0));
-    let start_time = Arc::new(std::sync::Mutex::new(Instant::now()));
 
     let h: Vec<JoinHandle<()>> = (0..args.threads)
         .map(|tid| {
-            let db = db.clone();
+            let db = bkt.clone();
             let tk: &Vec<Vec<u8>> = unsafe { std::mem::transmute(&keys[tid]) };
             let total_ops = total_ops.clone();
-            let barrier = Arc::clone(&barrier);
+            let ready_barrier = Arc::clone(&ready_barrier);
+            let start_barrier = Arc::clone(&start_barrier);
             let mode = args.mode.clone();
             let insert_ratio = args.insert_ratio;
-            let st = start_time.clone();
             let val = value.clone();
-            let prefix = format!("key_{tid}");
+            let prefix = format!("key_{tid}_");
 
             std::thread::spawn(move || {
-                // coreid::bind_core(tid);
+                coreid::bind_core(tid);
                 let mut round = 0;
-                barrier.wait();
-
-                {
-                    if let Ok(mut guard) = st.try_lock() {
-                        *guard = Instant::now();
-                    }
-                }
+                ready_barrier.wait();
+                start_barrier.wait();
                 match mode.as_str() {
                     "insert" => {
                         for key in tk {
@@ -202,12 +214,15 @@ fn main() {
         })
         .collect();
 
+    ready_barrier.wait();
+    let start_time = Instant::now();
+    start_barrier.wait();
+
     for x in h {
         x.join().unwrap();
     }
 
-    let test_start = start_time.lock().unwrap();
-    let duration = test_start.elapsed();
+    let duration = start_time.elapsed();
     let total = total_ops.load(std::sync::atomic::Ordering::Relaxed);
     let ops = (total as f64 / duration.as_secs_f64()) as usize;