diff --git a/core/src/db/SnapshotHandlers.h b/core/src/db/SnapshotHandlers.h
index fc81534cab3f532634af165af774423dd1f45a44..fe8602f8c98391777658b8ce4c79523da67d2dc9 100644
--- a/core/src/db/SnapshotHandlers.h
+++ b/core/src/db/SnapshotHandlers.h
@@ -25,7 +25,7 @@
 namespace milvus {
 namespace engine {
 
-struct LoadVectorFieldElementHandler : public snapshot::IterateHandler<snapshot::FieldElement> {
+struct LoadVectorFieldElementHandler : public snapshot::FieldElementIterator {
     using ResourceT = snapshot::FieldElement;
     using BaseT = snapshot::IterateHandler<ResourceT>;
     LoadVectorFieldElementHandler(const server::ContextPtr& context, snapshot::ScopedSnapshotT ss,
@@ -38,7 +38,7 @@ struct LoadVectorFieldElementHandler : public snapshot::IterateHandler<snapshot:
     const snapshot::FieldPtr field_;
 };
 
-struct LoadVectorFieldHandler : public snapshot::IterateHandler<snapshot::Field> {
+struct LoadVectorFieldHandler : public snapshot::FieldIterator {
     using ResourceT = snapshot::Field;
     using BaseT = snapshot::IterateHandler<ResourceT>;
     LoadVectorFieldHandler(const server::ContextPtr& context, snapshot::ScopedSnapshotT ss);
@@ -49,7 +49,7 @@ struct LoadVectorFieldHandler : public snapshot::IterateHandler<snapshot::Field>
     const server::ContextPtr context_;
 };
 
-struct SegmentsToSearchCollector : public snapshot::IterateHandler<snapshot::SegmentCommit> {
+struct SegmentsToSearchCollector : public snapshot::SegmentCommitIterator {
     using ResourceT = snapshot::SegmentCommit;
     using BaseT = snapshot::IterateHandler<ResourceT>;
     SegmentsToSearchCollector(snapshot::ScopedSnapshotT ss, snapshot::IDS_TYPE& segment_ids);
@@ -60,7 +60,7 @@ struct SegmentsToSearchCollector : public snapshot::IterateHandler<snapshot::Seg
     snapshot::IDS_TYPE& segment_ids_;
 };
 
-struct SegmentsToIndexCollector : public snapshot::IterateHandler<snapshot::SegmentCommit> {
+struct SegmentsToIndexCollector : public snapshot::SegmentCommitIterator {
     using ResourceT = snapshot::SegmentCommit;
     using BaseT = snapshot::IterateHandler<ResourceT>;
     SegmentsToIndexCollector(snapshot::ScopedSnapshotT ss, const std::string& field_name,
@@ -74,7 +74,7 @@ struct SegmentsToIndexCollector : public snapshot::IterateHandler<snapshot::Segm
 };
 
 ///////////////////////////////////////////////////////////////////////////////
-struct GetEntityByIdSegmentHandler : public snapshot::IterateHandler<snapshot::Segment> {
+struct GetEntityByIdSegmentHandler : public snapshot::SegmentIterator {
     using ResourceT = snapshot::Segment;
     using BaseT = snapshot::IterateHandler<ResourceT>;
     GetEntityByIdSegmentHandler(const server::ContextPtr& context, snapshot::ScopedSnapshotT ss,
diff --git a/core/src/db/engine/ExecutionEngineImpl.cpp b/core/src/db/engine/ExecutionEngineImpl.cpp
index ba6ba691b21d4e78f61bfc1a0b56a8c6201119cf..fdafccfeef610837ba2a3ed080d8e3ef43c13879 100644
--- a/core/src/db/engine/ExecutionEngineImpl.cpp
+++ b/core/src/db/engine/ExecutionEngineImpl.cpp
@@ -742,8 +742,8 @@ ExecutionEngineImpl::BuildKnowhereIndex(const std::string& field_name, const Col
     auto field_json = field->GetParams();
     auto dimension = field_json[milvus::knowhere::meta::DIM];
 
-    auto segment_commit = snapshot->GetSegmentCommitBySegmentId(segment->GetID());
-    auto row_count = segment_commit->GetRowCount();
+    snapshot::SIZE_TYPE row_count;
+    snapshot->GetSegmentRowCount(segment->GetID(), row_count);
 
     milvus::json conf = index_info.extra_params_;
     conf[knowhere::meta::DIM] = dimension;
diff --git a/core/src/db/snapshot/CompoundOperations.cpp b/core/src/db/snapshot/CompoundOperations.cpp
index 97805c19da016b4d6e1039ad9e0ab34d308e09ee..84818d1ea28aff4212df88aa58af41134c11ac8e 100644
--- a/core/src/db/snapshot/CompoundOperations.cpp
+++ b/core/src/db/snapshot/CompoundOperations.cpp
@@ -17,6 +17,7 @@
 #include <vector>
 
 #include "db/meta/MetaAdapter.h"
+#include "db/snapshot/IterateHandler.h"
 #include "db/snapshot/OperationExecutor.h"
 #include "db/snapshot/ResourceContext.h"
 #include "db/snapshot/Snapshots.h"
@@ -383,18 +384,21 @@ DropAllIndexOperation::DropAllIndexOperation(const OperationContext& context, Sc
 
 Status
 DropAllIndexOperation::PreCheck() {
-    if (context_.stale_field_element == nullptr) {
+    if (context_.stale_field_elements.size() == 0) {
         std::stringstream emsg;
         emsg << GetRepr() << ". Stale field element is requried";
         return Status(SS_INVALID_CONTEX_ERROR, emsg.str());
     }
 
-    if (!GetStartedSS()->GetResource<FieldElement>(context_.stale_field_element->GetID())) {
-        std::stringstream emsg;
-        emsg << GetRepr() << ".  Specified field element " << context_.stale_field_element->GetName();
-        emsg << " is stale";
-        return Status(SS_INVALID_CONTEX_ERROR, emsg.str());
+    for (auto stale_fe : context_.stale_field_elements) {
+        if (!GetStartedSS()->GetResource<FieldElement>(stale_fe->GetID())) {
+            std::stringstream emsg;
+            emsg << GetRepr() << ".  Specified field element " << stale_fe->GetName();
+            emsg << " is stale";
+            return Status(SS_INVALID_CONTEX_ERROR, emsg.str());
+        }
     }
+
     // TODO: Check type
     return Status::OK();
 }
@@ -406,7 +410,6 @@ DropAllIndexOperation::DoExecute(StorePtr store) {
     OperationContext cc_context;
     {
         auto context = context_;
-        context.stale_field_elements.push_back(context.stale_field_element);
 
         FieldCommitOperation fc_op(context, GetAdjustedSS());
         STATUS_CHECK(fc_op(store));
@@ -430,20 +433,40 @@ DropAllIndexOperation::DoExecute(StorePtr store) {
     }
 
     std::map<ID_TYPE, std::vector<SegmentCommitPtr>> p_sc_map;
-    for (auto& kv : segment_files) {
-        if (kv.second->GetFieldElementId() != context_.stale_field_element->GetID()) {
-            continue;
-        }
 
+    std::set<ID_TYPE> stale_fe_ids;
+    for (auto& fe : context_.stale_field_elements) {
+        stale_fe_ids.insert(fe->GetID());
+    }
+
+    auto seg_executor = [&](const SegmentPtr& segment, SegmentIterator* handler) -> Status {
+        auto sf_ids = handler->ss_->GetSegmentFileIds(segment->GetID());
+        if (sf_ids.size() == 0) {
+            return Status::OK();
+        }
         auto context = context_;
-        context.stale_segment_files.push_back(kv.second.Get());
+        for (auto& sf_id : sf_ids) {
+            auto sf = handler->ss_->GetResource<SegmentFile>(sf_id);
+            if (stale_fe_ids.find(sf->GetFieldElementId()) == stale_fe_ids.end()) {
+                continue;
+            }
+            context.stale_segment_files.push_back(sf);
+        }
+        if (context.stale_segment_files.size() == 0) {
+            return Status::OK();
+        }
         SegmentCommitOperation sc_op(context, GetAdjustedSS());
         STATUS_CHECK(sc_op(store));
         STATUS_CHECK(sc_op.GetResource(context.new_segment_commit));
         auto segc_ctx_p = ResourceContextBuilder<SegmentCommit>().SetOp(meta::oUpdate).CreatePtr();
         AddStepWithLsn(*context.new_segment_commit, context.lsn, segc_ctx_p);
         p_sc_map[context.new_segment_commit->GetPartitionId()].push_back(context.new_segment_commit);
-    }
+        return Status::OK();
+    };
+
+    auto segment_iter = std::make_shared<SegmentIterator>(GetAdjustedSS(), seg_executor);
+    segment_iter->Iterate();
+    STATUS_CHECK(segment_iter->GetStatus());
 
     for (auto& kv : p_sc_map) {
         auto& partition_id = kv.first;
diff --git a/core/src/db/snapshot/Context.h b/core/src/db/snapshot/Context.h
index 5987d4f5d6b818c92e52b8ba5690f32c634481ec..ad6cb02fc69c27af21c810400548ef9426f6d0be 100644
--- a/core/src/db/snapshot/Context.h
+++ b/core/src/db/snapshot/Context.h
@@ -66,9 +66,6 @@ struct OperationContext {
 
     std::vector<SegmentPtr> stale_segments;
 
-    FieldPtr prev_field = nullptr;
-    FieldElementPtr prev_field_element = nullptr;
-    FieldElementPtr stale_field_element = nullptr;
     std::vector<FieldElementPtr> new_field_elements;
     std::vector<FieldElementPtr> stale_field_elements;
 
diff --git a/core/src/db/snapshot/IterateHandler.h b/core/src/db/snapshot/IterateHandler.h
index 034b3299cc10b9d50eaabffca50d2102634c0e40..cb72aa6d813d6ef4081375b8826fb7f6da295faf 100644
--- a/core/src/db/snapshot/IterateHandler.h
+++ b/core/src/db/snapshot/IterateHandler.h
@@ -72,6 +72,7 @@ struct IterateHandler : public std::enable_shared_from_this<IterateHandler<T>> {
 
 using CollectionIterator = IterateHandler<Collection>;
 using PartitionIterator = IterateHandler<Partition>;
+using SegmentCommitIterator = IterateHandler<SegmentCommit>;
 using SegmentIterator = IterateHandler<Segment>;
 using SegmentFileIterator = IterateHandler<SegmentFile>;
 using FieldIterator = IterateHandler<Field>;
diff --git a/core/src/db/snapshot/Snapshot.cpp b/core/src/db/snapshot/Snapshot.cpp
index d6ba6cc0a23e7827271f40a71182bb5004dea9d7..df72ca4696b9903de9716df9ea1c508e7144b0c3 100644
--- a/core/src/db/snapshot/Snapshot.cpp
+++ b/core/src/db/snapshot/Snapshot.cpp
@@ -130,6 +130,19 @@ Snapshot::Snapshot(StorePtr store, ID_TYPE ss_id) {
     RefAll();
 }
 
+Status
+Snapshot::GetSegmentRowCount(ID_TYPE segment_id, SIZE_TYPE& row_cnt) const {
+    auto sc = GetSegmentCommitBySegmentId(segment_id);
+    if (!sc) {
+        std::stringstream emsg;
+        emsg << "Snapshot::GetSegmentRowCount: Specified segment \"" << segment_id;
+        emsg << "\" not found";
+        return Status(SS_NOT_FOUND_ERROR, emsg.str());
+    }
+    row_cnt = sc->GetRowCount();
+    return Status::OK();
+}
+
 FieldPtr
 Snapshot::GetField(const std::string& name) const {
     auto it = field_names_map_.find(name);
diff --git a/core/src/db/snapshot/Snapshot.h b/core/src/db/snapshot/Snapshot.h
index 45250f6ec424f23718f42c08d95b5b273ec5608f..2400537eb82fa4123af45a20aa07b2b31494ed18 100644
--- a/core/src/db/snapshot/Snapshot.h
+++ b/core/src/db/snapshot/Snapshot.h
@@ -131,7 +131,6 @@ class Snapshot : public ReferenceProxy {
     GetFieldElement(const std::string& field_name, const std::string& field_element_name,
                     FieldElementPtr& field_element) const;
 
-    // PXU TODO: add const. Need to change Scopedxxxx::Get
     SegmentCommitPtr
     GetSegmentCommitBySegmentId(ID_TYPE segment_id) const {
         auto it = seg_segc_map_.find(segment_id);
@@ -140,6 +139,9 @@ class Snapshot : public ReferenceProxy {
         return GetResource<SegmentCommit>(it->second);
     }
 
+    Status
+    GetSegmentRowCount(ID_TYPE segment_id, SIZE_TYPE&) const;
+
     std::vector<std::string>
     GetPartitionNames() const {
         std::vector<std::string> names;
diff --git a/core/unittest/db/test_snapshot.cpp b/core/unittest/db/test_snapshot.cpp
index 966e6b63ec7716629b78fa921e47daa100178d5f..66b11cb913a377b484954d02c5fd8b8f865bfc13 100644
--- a/core/unittest/db/test_snapshot.cpp
+++ b/core/unittest/db/test_snapshot.cpp
@@ -573,14 +573,14 @@ TEST_F(SnapshotTest, IndexTest) {
 
     OperationContext d_a_i_ctx;
     d_a_i_ctx.lsn = next_lsn();
-    d_a_i_ctx.stale_field_element = ss->GetResource<FieldElement>(field_element_id);
+    d_a_i_ctx.stale_field_elements.push_back(ss->GetResource<FieldElement>(field_element_id));
 
     FieldElement::Ptr fe;
     status = ss->GetFieldElement(sf_context.field_name, sf_context.field_element_name,
             fe);
 
     ASSERT_TRUE(status.ok());
-    ASSERT_EQ(fe, d_a_i_ctx.stale_field_element);
+    ASSERT_EQ(fe, d_a_i_ctx.stale_field_elements[0]);
 
     auto drop_all_index_op = std::make_shared<DropAllIndexOperation>(d_a_i_ctx, ss);
     status = drop_all_index_op->Push();