diff --git a/src/common/hist_util.cuh b/src/common/hist_util.cuh
index cf1043ddb399..b95d9c5c1917 100644
--- a/src/common/hist_util.cuh
+++ b/src/common/hist_util.cuh
@@ -295,10 +295,47 @@ void ProcessSlidingWindow(AdapterBatch const &batch, MetaInfo const &info,
                                  &cuts_ptr,
                                  &column_sizes_scan,
                                  &sorted_entries);
+
+  auto cuts_ptr_h = cuts_ptr.HostVector();
+  std::cout << "cuts ptr ------------------ num_cuts: " << num_cuts << std::endl;
+  for(uint64_t i : cuts_ptr_h) {
+      std::cout << i <<  " " << std::endl;
+  }
+  std::cout << "cuts ptr -- end----------------" << std::endl;
+
+    thrust::host_vector<size_t> column_sizes_scan_h = column_sizes_scan;
+    std::cout << "The column_sizes_scan_h : " << std::endl;
+    for (int i = 0; i < column_sizes_scan_h.size(); i++) {
+        std::cout << "column_sizes_scan_h: " << column_sizes_scan_h[i] << " ";
+    }
+    std::cout << "----------------------------------" << std::endl;
+
+  thrust::host_vector<Entry> sorted_entries_h = sorted_entries;
+  std::cout << "++++++++ The Entry without sorting: ++++++++++ " << std::endl;
+  for (int i = 0; i < sorted_entries_h.size(); i++) {
+      if (i % 4 == 0) {
+          std::cout << std::endl;
+      }
+      std::cout << sorted_entries_h[i].fvalue << " ";
+
+  }
+
+
   dh::XGBDeviceAllocator<char> alloc;
   thrust::sort(thrust::cuda::par(alloc), sorted_entries.begin(),
                sorted_entries.end(), detail::EntryCompareOp());
 
+    thrust::host_vector<Entry> sorted_entries_h_again = sorted_entries;
+    std::cout << std::endl;
+    std::cout << "------------The Entry with sorting: -----------------" << std::endl;
+    std::cout << "------------The Entry with sorting: -----------------" << std::endl;
+    for (int i = 0; i < sorted_entries_h_again.size(); i++) {
+        std::cout << sorted_entries_h_again[i].fvalue << " ";
+        if (i % 150 == 0 && i != 0) {
+            std::cout << std::endl;
+        }
+    }
+    std::cout << std::endl;
   if (sketch_container->HasCategorical()) {
     auto d_cuts_ptr = cuts_ptr.DeviceSpan();
     detail::RemoveDuplicatedCategories(device, info, d_cuts_ptr, &sorted_entries, nullptr,
@@ -311,6 +348,10 @@ void ProcessSlidingWindow(AdapterBatch const &batch, MetaInfo const &info,
   sketch_container->Push(dh::ToSpan(sorted_entries),
                          dh::ToSpan(column_sizes_scan), d_cuts_ptr,
                          h_cuts_ptr.back());
+
+  std::cout << std::endl;
+  std::cout << "-----------------the sketch_container ----------------- " << std::endl;
+
   sorted_entries.clear();
   sorted_entries.shrink_to_fit();
 }
@@ -414,6 +455,8 @@ void AdapterDeviceSketch(Batch batch, int num_bins,
   size_t num_rows = batch.NumRows();
   size_t num_cols = batch.NumCols();
   size_t num_cuts_per_feature = detail::RequiredSampleCutsPerColumn(num_bins, num_rows);
+  std::cout << "AdapterDeviceSketch num_rows: " << num_rows << " num_cols: " << num_cols <<
+  " num_cuts_per_feature: " << num_cuts_per_feature << std::endl;
   auto device = sketch_container->DeviceIdx();
   bool weighted = !info.weights_.Empty();
 
diff --git a/src/common/hist_util.h b/src/common/hist_util.h
index e829752dae3d..d9bbc994f02f 100644
--- a/src/common/hist_util.h
+++ b/src/common/hist_util.h
@@ -65,6 +65,27 @@ class HistogramCuts {
   // storing minimum value in a sketch set.
   HostDeviceVector<float> min_vals_;  // NOLINT
 
+  void show() {
+      auto cut_values_h = cut_values_.HostVector();
+      std::cout << "HistogramCuts, cut_values_h: " << std::endl;
+      for (auto v : cut_values_h) {
+          std::cout << v << " ";
+      }
+      std::cout << std::endl;
+      auto cut_ptrs_h = cut_ptrs_.HostVector();
+      std::cout << "cut_ptrs_: " << std::endl;
+      for (auto v : cut_ptrs_h) {
+          std::cout << v << " ";
+      }
+      std::cout << std::endl;
+      auto min_vals_h = min_vals_.HostVector();
+      std::cout << "min_vals_h: " << std::endl;
+      for (auto v : min_vals_h) {
+          std::cout << v << " ";
+      }
+      std::cout << std::endl;
+  }
+
   HistogramCuts();
   HistogramCuts(HistogramCuts const& that) { this->Copy(that); }
 
diff --git a/src/common/quantile.cu b/src/common/quantile.cu
index e7f09fc4d56a..abb45f835841 100644
--- a/src/common/quantile.cu
+++ b/src/common/quantile.cu
@@ -310,6 +310,7 @@ void SketchContainer::Push(Span<Entry const> entries, Span<size_t> columns_ptr,
   Span<SketchEntry> out;
   dh::device_vector<SketchEntry> cuts;
   bool first_window = this->Current().empty();
+  std::cout << "SketchContainer::Push " << total_cuts << std::endl;
   if (!first_window) {
     cuts.resize(total_cuts);
     out = dh::ToSpan(cuts);
@@ -413,6 +414,7 @@ void SketchContainer::Prune(size_t to) {
   auto const& h_feature_types = feature_types_.ConstHostSpan();
   for (bst_feature_t i = 0; i < num_columns_; ++i) {
     size_t length = this->Column(i).size();
+    std::cout << "column: " << i << " SketchContainer Prune len: " << length << " maxBins: " << to << std::endl;
     length = std::min(length, to);
     if (IsCat(h_feature_types, i)) {
       length = this->Column(i).size();
@@ -588,6 +590,7 @@ void SketchContainer::MakeCuts(Context const* ctx, HistogramCuts* p_cuts, bool i
   // Sync between workers.
   this->AllReduce(ctx, is_column_split);
 
+  std::cout << "MakeCuts prune to " << num_bins_ + 1 << std::endl;
   // Prune to final number of bins.
   this->Prune(num_bins_ + 1);
   this->FixError();
diff --git a/src/common/quantile.cuh b/src/common/quantile.cuh
index 898da03a0dce..983354433ad1 100644
--- a/src/common/quantile.cuh
+++ b/src/common/quantile.cuh
@@ -4,6 +4,7 @@
 #ifndef XGBOOST_COMMON_QUANTILE_CUH_
 #define XGBOOST_COMMON_QUANTILE_CUH_
 
+#include <thrust/host_vector.h>
 #include "xgboost/span.h"
 #include "xgboost/data.h"
 #include "device_helpers.cuh"
@@ -87,6 +88,26 @@ class SketchContainer {
   }
 
  public:
+    void show() {
+      std::cout << "SketchContainer, rows: " << this->num_rows_
+      << "cols: " << this->num_columns_
+      << std::endl;
+
+      thrust::host_vector<SketchEntry> entry_h = this->Current();
+      std::cout << "entries in SketchContainer!" << std::endl;
+      for (auto v : entry_h) {
+          std::cout << v << std::endl;
+      }
+      std::cout << std::endl;
+
+      auto columns_ptr_h = columns_ptr_.HostVector();
+
+      std::cout << "columns_ptr in SketchContainer!" << std::endl;
+      for (auto v: columns_ptr_h) {
+          std::cout << v << " ";
+      }
+      std::cout << std::endl;
+  }
   /* \breif GPU quantile structure, with sketch data for each columns.
    *
    * \param max_bin     Maximum number of bins per columns
diff --git a/src/data/ellpack_page.cuh b/src/data/ellpack_page.cuh
index c64462082481..47a537454222 100644
--- a/src/data/ellpack_page.cuh
+++ b/src/data/ellpack_page.cuh
@@ -210,6 +210,10 @@ class EllpackPageImpl {
   [[nodiscard]] EllpackDeviceAccessor GetHostAccessor(
       common::Span<FeatureType const> feature_types = {}) const;
 
+  void show() {
+      std::cout << "ELLpack is_dense: " << is_dense << " row_stride: " << row_stride
+      << " base_rowid: " << base_rowid << " n_rows: " << n_rows << std::endl;
+  }
  private:
   /*!
    * \brief Compress a single page of CSR data into ELLPACK.
diff --git a/src/data/iterative_dmatrix.cc b/src/data/iterative_dmatrix.cc
index 0d75d0651e26..d9c47b4d7f56 100644
--- a/src/data/iterative_dmatrix.cc
+++ b/src/data/iterative_dmatrix.cc
@@ -183,10 +183,14 @@ void IterativeDMatrix::InitFromCPU(Context const* ctx, BatchParam const& p,
       CHECK_EQ(n_features, num_cols()) << "Inconsistent number of columns.";
     }
     size_t batch_size = num_rows();
+
     batch_nnz.push_back(nnz_cnt());
     nnz += batch_nnz.back();
     accumulated_rows += batch_size;
     n_batches++;
+
+    std::cout << "nnz: " << nnz << " batch_size: " << batch_size << std::endl;
+
   } while (iter.Next());
   iter.Reset();
 
@@ -199,6 +203,7 @@ void IterativeDMatrix::InitFromCPU(Context const* ctx, BatchParam const& p,
   })) << "Something went wrong during iteration.";
 
   CHECK_GE(n_features, 1) << "Data must has at least 1 column.";
+  std::cout << "Total nnz: " << nnz << " accumulated_rows: " << accumulated_rows << std::endl;
 
   /**
    * Generate quantiles
diff --git a/src/data/iterative_dmatrix.cu b/src/data/iterative_dmatrix.cu
index 09a3976d785c..bf100b1479f7 100644
--- a/src/data/iterative_dmatrix.cu
+++ b/src/data/iterative_dmatrix.cu
@@ -86,6 +86,8 @@ void IterativeDMatrix::InitFromCUDA(Context const* ctx, BatchParam const& p,
                           }));
     nnz += thrust::reduce(thrust::cuda::par(alloc), row_counts.begin(), row_counts.end());
     batches++;
+    std::cout << "nnz: " << nnz << " batch_rows: " << batch_rows <<
+    " accumulated_rows: " << accumulated_rows << std::endl;
   } while (iter.Next());
   iter.Reset();
 
@@ -106,6 +108,7 @@ void IterativeDMatrix::InitFromCUDA(Context const* ctx, BatchParam const& p,
     sketch_containers.shrink_to_fit();
 
     final_sketch.MakeCuts(ctx, &cuts, this->info_.IsColumnSplit());
+    final_sketch.show();
   } else {
     GetCutsFromRef(ctx, ref, Info().num_col_, p, &cuts);
   }
@@ -113,6 +116,8 @@ void IterativeDMatrix::InitFromCUDA(Context const* ctx, BatchParam const& p,
   this->info_.num_row_ = accumulated_rows;
   this->info_.num_nonzero_ = nnz;
 
+  cuts.show();
+
   auto init_page = [this, &cuts, row_stride, accumulated_rows, get_device]() {
     if (!ellpack_) {
       // Should be put inside the while loop to protect against empty batch.  In
@@ -165,6 +170,8 @@ void IterativeDMatrix::InitFromCUDA(Context const* ctx, BatchParam const& p,
     CHECK_EQ(proxy->Info().labels.Size(), 0);
   }
 
+  ellpack_->Impl()->show();
+
   iter.Reset();
   // Synchronise worker columns
   info_.SynchronizeNumberOfColumns(ctx);