[Join] Remove redundant copies.

Devjiu · Devjiu · commit 3e26fa2ca0f2 · 2023-09-15T16:04:37.000Z
This commit removes useless copying(memcpy) in `getAllTableColumnFragments`. Also some parallelization added. Resolves: #574 Signed-off-by: Dmitrii Makarenko <dmitrii.makarenko@intel.com>
diff --git a/omniscidb/QueryEngine/ColumnFetcher.cpp b/omniscidb/QueryEngine/ColumnFetcher.cpp
@@ -16,15 +16,16 @@
 
 #include "QueryEngine/ColumnFetcher.h"
 
-#include <memory>
-
 #include "DataMgr/ArrayNoneEncoder.h"
 #include "QueryEngine/ErrorHandling.h"
 #include "QueryEngine/Execute.h"
 #include "Shared/Intervals.h"
 #include "Shared/likely.h"
 #include "Shared/sqltypes.h"
 
+#include <tbb/parallel_for.h>
+#include <memory>
+
 namespace {
 
 std::string getMemoryLevelString(Data_Namespace::MemoryLevel memoryLevel) {
@@ -239,16 +240,17 @@ const int8_t* ColumnFetcher::getAllTableColumnFragments(
   int db_id = col_info->db_id;
   int table_id = col_info->table_id;
   int col_id = col_info->column_id;
+
   const auto fragments_it = all_tables_fragments.find({db_id, table_id});
   CHECK(fragments_it != all_tables_fragments.end());
+
   const auto fragments = fragments_it->second;
   const auto frag_count = fragments->size();
   std::vector<std::unique_ptr<ColumnarResults>> column_frags;
   const ColumnarResults* table_column = nullptr;
   const InputDescriptor table_desc(db_id, table_id, int(0));
   {
     std::lock_guard<std::mutex> columnar_conversion_guard(columnar_fetch_mutex_);
-
     auto col_token = data_provider_->getZeroCopyColumnData(*col_info);
     if (col_token != nullptr) {
       size_t num_rows = col_token->getSize() / col_token->getType()->size();
@@ -262,44 +264,111 @@ const int8_t* ColumnFetcher::getAllTableColumnFragments(
     }
 
     auto column_it = columnarized_scan_table_cache_.find({table_id, col_id});
-    if (column_it == columnarized_scan_table_cache_.end()) {
-      for (size_t frag_id = 0; frag_id < frag_count; ++frag_id) {
-        if (executor_->getConfig()
-                .exec.interrupt.enable_non_kernel_time_query_interrupt &&
-            executor_->checkNonKernelTimeInterrupted()) {
-          throw QueryExecutionError(Executor::ERR_INTERRUPTED);
-        }
-        std::list<std::shared_ptr<Chunk_NS::Chunk>> chunk_holder;
-        std::list<ChunkIter> chunk_iter_holder;
-        const auto& fragment = (*fragments)[frag_id];
-        if (fragment.isEmptyPhysicalFragment()) {
-          continue;
-        }
-        auto chunk_meta_it = fragment.getChunkMetadataMap().find(col_id);
-        CHECK(chunk_meta_it != fragment.getChunkMetadataMap().end());
-        auto col_buffer = getOneTableColumnFragment(col_info,
-                                                    static_cast<int>(frag_id),
-                                                    all_tables_fragments,
-                                                    chunk_holder,
-                                                    chunk_iter_holder,
-                                                    Data_Namespace::CPU_LEVEL,
-                                                    int(0),
-                                                    device_allocator);
-        column_frags.push_back(
-            std::make_unique<ColumnarResults>(executor_->row_set_mem_owner_,
-                                              col_buffer,
-                                              fragment.getNumTuples(),
-                                              chunk_meta_it->second->type(),
-                                              thread_idx));
+    if (column_it != columnarized_scan_table_cache_.end()) {
+      table_column = column_it->second.get();
+      return ColumnFetcher::transferColumnIfNeeded(
+          table_column, 0, memory_level, device_id, device_allocator);
+    }
+
+    size_t total_row_count = 0;
+    for (size_t frag_id = 0; frag_id < frag_count; ++frag_id) {
+      if (executor_->getConfig().exec.interrupt.enable_non_kernel_time_query_interrupt &&
+          executor_->checkNonKernelTimeInterrupted()) {
+        throw QueryExecutionError(Executor::ERR_INTERRUPTED);
       }
-      auto merged_results =
-          ColumnarResults::mergeResults(executor_->row_set_mem_owner_, column_frags);
+      const auto& fragment = (*fragments)[frag_id];
+      const auto& rows_in_frag = fragment.getNumTuples();
+      total_row_count += rows_in_frag;
+    }
+
+    const auto& type_width = col_info->type->size();
+    auto write_ptr =
+        executor_->row_set_mem_owner_->allocate(type_width * total_row_count);
+    std::vector<std::pair<int8_t*, size_t>> write_ptrs;
+    std::vector<size_t> valid_fragments;
+    for (size_t frag_id = 0; frag_id < frag_count; ++frag_id) {
+      const auto& fragment = (*fragments)[frag_id];
+      if (fragment.isEmptyPhysicalFragment()) {
+        continue;
+      }
+      CHECK_EQ(type_width, fragment.getChunkMetadataMap().at(col_id)->type()->size());
+      write_ptrs.push_back({write_ptr, fragment.getNumTuples() * type_width});
+      write_ptr += fragment.getNumTuples() * type_width;
+      valid_fragments.push_back(frag_id);
+    }
+
+    if (write_ptrs.empty()) {
+      std::unique_ptr<ColumnarResults> merged_results(nullptr);
+
       table_column = merged_results.get();
       columnarized_scan_table_cache_.emplace(std::make_pair(table_id, col_id),
                                              std::move(merged_results));
-    } else {
-      table_column = column_it->second.get();
+
+      return ColumnFetcher::transferColumnIfNeeded(
+          table_column, 0, memory_level, device_id, device_allocator);
     }
+
+    size_t valid_frag_count = valid_fragments.size();
+    tbb::parallel_for(
+        tbb::blocked_range<size_t>(0, valid_frag_count),
+        [&](const tbb::blocked_range<size_t>& frag_ids) {
+          for (size_t v_frag_id = frag_ids.begin(); v_frag_id < frag_ids.end();
+               ++v_frag_id) {
+            std::list<std::shared_ptr<Chunk_NS::Chunk>> chunk_holder;
+            std::list<ChunkIter> chunk_iter_holder;
+            size_t frag_id = valid_fragments[v_frag_id];
+            const auto& fragment = (*fragments)[frag_id];
+            auto chunk_meta_it = fragment.getChunkMetadataMap().find(col_id);
+            CHECK(chunk_meta_it != fragment.getChunkMetadataMap().end());
+            std::shared_ptr<Chunk_NS::Chunk> chunk;
+            // Fixed length arrays are also included here.
+            const bool is_varlen =
+                col_info->type->isString() || col_info->type->isArray();
+            int8_t* col_buffer;
+            {
+              ChunkKey chunk_key{
+                  db_id, fragment.physicalTableId, col_id, fragment.fragmentId};
+              std::unique_ptr<std::lock_guard<std::mutex>> varlen_chunk_lock;
+              if (is_varlen) {
+                varlen_chunk_lock.reset(
+                    new std::lock_guard<std::mutex>(varlen_chunk_fetch_mutex_));
+              }
+              chunk = data_provider_->getChunk(col_info,
+                                               chunk_key,
+                                               Data_Namespace::CPU_LEVEL,
+                                               0,
+                                               chunk_meta_it->second->numBytes(),
+                                               chunk_meta_it->second->numElements());
+              std::lock_guard<std::mutex> chunk_list_lock(chunk_list_mutex_);
+              chunk_holder.push_back(chunk);
+            }
+            if (is_varlen) {
+              CHECK_GT(table_id, 0);
+              CHECK(chunk_meta_it != fragment.getChunkMetadataMap().end());
+              chunk_iter_holder.push_back(chunk->begin_iterator(chunk_meta_it->second));
+              auto& chunk_iter = chunk_iter_holder.back();
+              col_buffer = reinterpret_cast<int8_t*>(&chunk_iter);
+            } else {
+              auto ab = chunk->getBuffer();
+              CHECK(ab->getMemoryPtr());
+              col_buffer = ab->getMemoryPtr();  // @TODO(alex) change to use ChunkIter
+            }
+            memcpy(write_ptrs[frag_id].first, col_buffer, write_ptrs[frag_id].second);
+          }
+        });
+
+    std::vector<int8_t*> raw_write_ptrs;
+    raw_write_ptrs.reserve(frag_count);
+    for (size_t i = 0; i < frag_count; i++) {
+      raw_write_ptrs.emplace_back(write_ptrs[i].first);
+    }
+
+    std::unique_ptr<ColumnarResults> merged_results(new ColumnarResults(
+        std::move(raw_write_ptrs), total_row_count, col_info->type, thread_idx));
+
+    table_column = merged_results.get();
+    columnarized_scan_table_cache_.emplace(std::make_pair(table_id, col_id),
+                                           std::move(merged_results));
   }
   return ColumnFetcher::transferColumnIfNeeded(
       table_column, 0, memory_level, device_id, device_allocator);
diff --git a/omniscidb/QueryEngine/JoinHashTable/Runtime/JoinColumnIterator.h b/omniscidb/QueryEngine/JoinHashTable/Runtime/JoinColumnIterator.h
@@ -73,6 +73,7 @@ struct JoinColumnIterator {
   DEVICE FORCE_INLINE JoinColumnIterator& operator++() {
     index += step;
     index_inside_chunk += step;
+    // this loop is made to find index_of_chunk by total index of element
     while (chunk_data &&
            index_inside_chunk >= join_chunk_array[index_of_chunk].num_elems) {
       index_inside_chunk -= join_chunk_array[index_of_chunk].num_elems;
diff --git a/omniscidb/ResultSetRegistry/ColumnarResults.cpp b/omniscidb/ResultSetRegistry/ColumnarResults.cpp
@@ -122,28 +122,6 @@ ColumnarResults::ColumnarResults(std::shared_ptr<RowSetMemoryOwner> row_set_mem_
   }
 }
 
-ColumnarResults::ColumnarResults(std::shared_ptr<RowSetMemoryOwner> row_set_mem_owner,
-                                 const int8_t* one_col_buffer,
-                                 const size_t num_rows,
-                                 const hdk::ir::Type* target_type,
-                                 const size_t thread_idx)
-    : column_buffers_(1)
-    , num_rows_(num_rows)
-    , target_types_{target_type}
-    , parallel_conversion_(false)
-    , direct_columnar_conversion_(false)
-    , thread_idx_(thread_idx) {
-  auto timer = DEBUG_TIMER(__func__);
-
-  if (target_type->isVarLen()) {
-    throw ColumnarConversionNotSupported();
-  }
-  const auto buf_size = num_rows * target_type->size();
-  column_buffers_[0] =
-      reinterpret_cast<int8_t*>(row_set_mem_owner->allocate(buf_size, thread_idx_));
-  memcpy(((void*)column_buffers_[0]), one_col_buffer, buf_size);
-}
-
 ColumnarResults::ColumnarResults(const std::vector<int8_t*> one_col_buffer,
                                  const size_t num_rows,
                                  const hdk::ir::Type* target_type,
diff --git a/omniscidb/ResultSetRegistry/ColumnarResults.h b/omniscidb/ResultSetRegistry/ColumnarResults.h
@@ -67,12 +67,6 @@ class ColumnarResults {
                   const Config& config,
                   const bool is_parallel_execution_enforced = false);
 
-  ColumnarResults(const std::shared_ptr<RowSetMemoryOwner> row_set_mem_owner,
-                  const int8_t* one_col_buffer,
-                  const size_t num_rows,
-                  const hdk::ir::Type* target_type,
-                  const size_t thread_idx);
-
   ColumnarResults(const std::vector<int8_t*> one_col_buffer,
                   const size_t num_rows,
                   const hdk::ir::Type* target_type,
diff --git a/python/pyhdk/hdk.py b/python/pyhdk/hdk.py
@@ -2899,6 +2899,9 @@ def if_then_else(self, cond, true_val, false_val):
         """
         return self._builder.if_then_else(cond, true_val, false_val)
 
+    def clear_cache(self):
+        self._executor.clearMemory(self._data_mgr, 1)
+
 
 def init(**kwargs):
     if init._instance is None:
