diff --git a/src/kv/key.rs b/src/kv/key.rs
index 1bbe11e..b46510b 100644
--- a/src/kv/key.rs
+++ b/src/kv/key.rs
@@ -128,10 +128,6 @@ impl Key {
     }
 }
 
-pub trait HasKeys {
-    fn get_keys(&self) -> Vec<Key>;
-}
-
 impl From<Vec<u8>> for Key {
     fn from(v: Vec<u8>) -> Self {
         Key(v)
diff --git a/src/kv/mod.rs b/src/kv/mod.rs
index 7831bea..e394216 100644
--- a/src/kv/mod.rs
+++ b/src/kv/mod.rs
@@ -8,7 +8,7 @@ mod kvpair;
 mod value;
 
 pub use bound_range::{BoundRange, IntoOwnedRange};
-pub use key::{HasKeys, Key};
+pub use key::Key;
 pub use kvpair::KvPair;
 pub use value::Value;
 
diff --git a/src/request/mod.rs b/src/request/mod.rs
index 9252280..0f21efb 100644
--- a/src/request/mod.rs
+++ b/src/request/mod.rs
@@ -10,8 +10,9 @@ use tikv_client_store::{HasError, Request};
 
 pub use self::{
     plan::{
-        Collect, CollectAndMatchKey, CollectError, DefaultProcessor, Dispatch, ExtractError, Merge,
-        MergeResponse, MultiRegion, Plan, Process, ProcessResponse, ResolveLock, RetryRegion,
+        Collect, CollectAndMatchKey, CollectError, DefaultProcessor, Dispatch, ExtractError,
+        HasKeys, Merge, MergeResponse, MultiRegion, Plan, PreserveKey, Process, ProcessResponse,
+        ResolveLock, RetryRegion,
     },
     plan_builder::{PlanBuilder, SingleKey},
     shard::Shardable,
diff --git a/src/request/plan.rs b/src/request/plan.rs
index d9b3059..0f3bb51 100644
--- a/src/request/plan.rs
+++ b/src/request/plan.rs
@@ -2,7 +2,6 @@
 
 use crate::{
     backoff::Backoff,
-    kv::HasKeys,
     pd::PdClient,
     request::{KvRequest, Shardable},
     stats::tikv_stats,
@@ -340,11 +339,71 @@ where
     async fn execute(&self) -> Result<Self::Result> {
         let keys = self.inner.get_keys();
         let res = self.inner.execute().await?;
-        // TODO: should we check they have the same length?
         Ok(ResponseAndKeys(res, keys))
     }
 }
 
+pub trait HasKeys {
+    fn get_keys(&self) -> Vec<Key>;
+}
+
+// contains a response and the corresponding keys
+// currently only used for matching keys and values in pessimistic lock requests
+#[derive(Debug, Clone)]
+pub struct ResponseAndKeys<Resp>(Resp, Vec<Key>);
+
+impl<Resp: HasError> HasError for ResponseAndKeys<Resp> {
+    fn error(&mut self) -> Option<Error> {
+        self.0.error()
+    }
+}
+
+impl<Resp: HasLocks> HasLocks for ResponseAndKeys<Resp> {
+    fn take_locks(&mut self) -> Vec<tikv_client_proto::kvrpcpb::LockInfo> {
+        self.0.take_locks()
+    }
+}
+
+impl<Resp: HasRegionError> HasRegionError for ResponseAndKeys<Resp> {
+    fn region_error(&mut self) -> Option<Error> {
+        self.0.region_error()
+    }
+}
+
+impl Merge<ResponseAndKeys<kvrpcpb::PessimisticLockResponse>> for CollectAndMatchKey {
+    type Out = Vec<KvPair>;
+
+    fn merge(
+        &self,
+        input: Vec<Result<ResponseAndKeys<kvrpcpb::PessimisticLockResponse>>>,
+    ) -> Result<Self::Out> {
+        input
+            .into_iter()
+            .flat_map_ok(|ResponseAndKeys(mut resp, keys)| {
+                let values = resp.take_values();
+                let not_founds = resp.take_not_founds();
+                let v: Vec<_> = if not_founds.is_empty() {
+                    // Legacy TiKV does not distiguish not existing key and existing key
+                    // that with empty value. We assume that key does not exist if value
+                    // is empty.
+                    let values: Vec<Value> = values.into_iter().filter(|v| v.is_empty()).collect();
+                    keys.into_iter().zip(values).map(From::from).collect()
+                } else {
+                    assert_eq!(values.len(), not_founds.len());
+                    let values: Vec<Value> = values
+                        .into_iter()
+                        .zip(not_founds.into_iter())
+                        .filter_map(|(v, not_found)| if not_found { None } else { Some(v) })
+                        .collect();
+                    keys.into_iter().zip(values).map(From::from).collect()
+                };
+                // FIXME sucks to collect and re-iterate, but the iterators have different types
+                v.into_iter()
+            })
+            .collect()
+    }
+}
+
 #[cfg(test)]
 mod test {
     use super::*;
@@ -402,60 +461,3 @@ mod test {
             .for_each(|r| assert!(r.is_err()));
     }
 }
-
-// contains a response and the corresponding keys
-// currently only used for matching keys and values in pessimistic lock requests
-#[derive(Debug, Clone)]
-pub struct ResponseAndKeys<Resp>(Resp, Vec<Key>);
-
-impl<Resp: HasError> HasError for ResponseAndKeys<Resp> {
-    fn error(&mut self) -> Option<Error> {
-        self.0.error()
-    }
-}
-
-impl<Resp: HasLocks> HasLocks for ResponseAndKeys<Resp> {
-    fn take_locks(&mut self) -> Vec<tikv_client_proto::kvrpcpb::LockInfo> {
-        self.0.take_locks()
-    }
-}
-
-impl<Resp: HasRegionError> HasRegionError for ResponseAndKeys<Resp> {
-    fn region_error(&mut self) -> Option<Error> {
-        self.0.region_error()
-    }
-}
-
-impl Merge<ResponseAndKeys<kvrpcpb::PessimisticLockResponse>> for CollectAndMatchKey {
-    type Out = Vec<KvPair>;
-
-    fn merge(
-        &self,
-        input: Vec<Result<ResponseAndKeys<kvrpcpb::PessimisticLockResponse>>>,
-    ) -> Result<Self::Out> {
-        input
-            .into_iter()
-            .flat_map_ok(|ResponseAndKeys(mut resp, keys)| {
-                let values = resp.take_values();
-                let not_founds = resp.take_not_founds();
-                let v: Vec<_> = if not_founds.is_empty() {
-                    // Legacy TiKV does not distiguish not existing key and existing key
-                    // that with empty value. We assume that key does not exist if value
-                    // is empty.
-                    let values: Vec<Value> = values.into_iter().filter(|v| v.is_empty()).collect();
-                    keys.into_iter().zip(values).map(From::from).collect()
-                } else {
-                    assert_eq!(values.len(), not_founds.len());
-                    let values: Vec<Value> = values
-                        .into_iter()
-                        .zip(not_founds.into_iter())
-                        .filter_map(|(v, not_found)| if not_found { None } else { Some(v) })
-                        .collect();
-                    keys.into_iter().zip(values).map(From::from).collect()
-                };
-                // FIXME sucks to collect and re-iterate, but the iterators have different types
-                v.into_iter()
-            })
-            .collect()
-    }
-}
diff --git a/src/request/plan_builder.rs b/src/request/plan_builder.rs
index 7ee5a87..5df26c9 100644
--- a/src/request/plan_builder.rs
+++ b/src/request/plan_builder.rs
@@ -1,12 +1,12 @@
 // Copyright 2021 TiKV Project Authors. Licensed under Apache-2.0.
 
+use super::PreserveKey;
 use crate::{
     backoff::Backoff,
-    kv::HasKeys,
     pd::PdClient,
     request::{
-        DefaultProcessor, Dispatch, ExtractError, KvRequest, Merge, MergeResponse, MultiRegion,
-        Plan, Process, ProcessResponse, ResolveLock, RetryRegion, Shardable,
+        DefaultProcessor, Dispatch, ExtractError, HasKeys, KvRequest, Merge, MergeResponse,
+        MultiRegion, Plan, Process, ProcessResponse, ResolveLock, RetryRegion, Shardable,
     },
     store::Store,
     transaction::HasLocks,
@@ -15,8 +15,6 @@ use crate::{
 use std::{marker::PhantomData, sync::Arc};
 use tikv_client_store::HasError;
 
-use super::plan::PreserveKey;
-
 /// Builder type for plans (see that module for more).
 pub struct PlanBuilder<PdC: PdClient, P: Plan, Ph: PlanBuilderPhase> {
     pd_client: Arc<PdC>,
diff --git a/src/request/shard.rs b/src/request/shard.rs
index 4a565f5..e1300c5 100644
--- a/src/request/shard.rs
+++ b/src/request/shard.rs
@@ -1,16 +1,30 @@
 // Copyright 2021 TiKV Project Authors. Licensed under Apache-2.0.
 
 use crate::{
-    kv::HasKeys,
     pd::PdClient,
-    request::{Dispatch, KvRequest, Plan, ResolveLock, RetryRegion},
+    request::{Dispatch, HasKeys, KvRequest, Plan, PreserveKey, ResolveLock, RetryRegion},
     store::Store,
     Result,
 };
 use futures::stream::BoxStream;
 use std::sync::Arc;
 
-use super::plan::PreserveKey;
+macro_rules! impl_inner_shardable {
+    () => {
+        type Shard = P::Shard;
+
+        fn shards(
+            &self,
+            pd_client: &Arc<impl PdClient>,
+        ) -> BoxStream<'static, Result<(Self::Shard, Store)>> {
+            self.inner.shards(pd_client)
+        }
+
+        fn apply_shard(&mut self, shard: Self::Shard, store: &Store) -> Result<()> {
+            self.inner.apply_shard(shard, store)
+        }
+    };
+}
 
 pub trait Shardable {
     type Shard: Send;
@@ -40,48 +54,15 @@ impl<Req: KvRequest + Shardable> Shardable for Dispatch<Req> {
 }
 
 impl<P: Plan + Shardable, PdC: PdClient> Shardable for ResolveLock<P, PdC> {
-    type Shard = P::Shard;
-
-    fn shards(
-        &self,
-        pd_client: &Arc<impl PdClient>,
-    ) -> BoxStream<'static, Result<(Self::Shard, Store)>> {
-        self.inner.shards(pd_client)
-    }
-
-    fn apply_shard(&mut self, shard: Self::Shard, store: &Store) -> Result<()> {
-        self.inner.apply_shard(shard, store)
-    }
+    impl_inner_shardable!();
 }
 
 impl<P: Plan + HasKeys + Shardable> Shardable for PreserveKey<P> {
-    type Shard = P::Shard;
-
-    fn shards(
-        &self,
-        pd_client: &Arc<impl PdClient>,
-    ) -> BoxStream<'static, Result<(Self::Shard, Store)>> {
-        self.inner.shards(pd_client)
-    }
-
-    fn apply_shard(&mut self, shard: Self::Shard, store: &Store) -> Result<()> {
-        self.inner.apply_shard(shard, store)
-    }
+    impl_inner_shardable!();
 }
 
 impl<P: Plan + Shardable, PdC: PdClient> Shardable for RetryRegion<P, PdC> {
-    type Shard = P::Shard;
-
-    fn shards(
-        &self,
-        pd_client: &Arc<impl PdClient>,
-    ) -> BoxStream<'static, Result<(Self::Shard, Store)>> {
-        self.inner.shards(pd_client)
-    }
-
-    fn apply_shard(&mut self, shard: Self::Shard, store: &Store) -> Result<()> {
-        self.inner.apply_shard(shard, store)
-    }
+    impl_inner_shardable!();
 }
 
 #[macro_export]
diff --git a/src/transaction/requests.rs b/src/transaction/requests.rs
index 6b48c21..07667bb 100644
--- a/src/transaction/requests.rs
+++ b/src/transaction/requests.rs
@@ -1,9 +1,10 @@
 // Copyright 2020 TiKV Project Authors. Licensed under Apache-2.0.
 
 use crate::{
-    kv::HasKeys,
     pd::PdClient,
-    request::{Collect, DefaultProcessor, KvRequest, Merge, Process, Shardable, SingleKey},
+    request::{
+        Collect, DefaultProcessor, HasKeys, KvRequest, Merge, Process, Shardable, SingleKey,
+    },
     store::{store_stream_for_keys, store_stream_for_range_by_start_key, Store},
     timestamp::TimestampExt,
     transaction::HasLocks,
diff --git a/tests/integration_tests.rs b/tests/integration_tests.rs
index d3bb5f3..27f2ac2 100644
--- a/tests/integration_tests.rs
+++ b/tests/integration_tests.rs
@@ -290,7 +290,7 @@ async fn txn_write_million() -> Result<()> {
     assert_eq!(sum, 2usize.pow(NUM_BITS_KEY_PER_TXN + NUM_BITS_TXN));
 
     // test batch_get and batch_get_for_update
-    const SKIP_BITS: u32 = 6; // do not retrive all because there's a limit of message size
+    const SKIP_BITS: u32 = 7; // do not retrive all because there's a limit of message size
     let mut cur = 0u32;
     let keys = iter::repeat_with(|| {
         let v = cur;