SpeculativeTopNMap Class Reference

#include <SpeculativeTopN.h>

Public Member Functions
	SpeculativeTopNMap ()
	SpeculativeTopNMap (const ResultSet &rows, const std::vector< Analyzer::Expr * > &target_exprs, const size_t truncate_n)
void	reduce (SpeculativeTopNMap &that)
std::shared_ptr< ResultSet >	asRows (const RelAlgExecutionUnit &ra_exe_unit, std::shared_ptr< RowSetMemoryOwner > row_set_mem_owner, const QueryMemoryDescriptor &query_mem_desc, const Executor *executor, const size_t top_n, const bool desc) const

Private Attributes
std::unordered_map< int64_t, SpeculativeTopNVal >	map_
size_t	unknown_

Detailed Description

Definition at line 57 of file SpeculativeTopN.h.

Constructor & Destructor Documentation

SpeculativeTopNMap::SpeculativeTopNMap

(

)

Definition at line 23 of file SpeculativeTopN.cpp.

: unknown_(0) {}

SpeculativeTopNMap::SpeculativeTopNMap	(	const ResultSet &	rows,
		const std::vector< Analyzer::Expr * > &	target_exprs,
		const size_t	truncate_n
	)

Definition at line 25 of file SpeculativeTopN.cpp.

References CHECK, CHECK_EQ, map_, and unknown_.

    : unknown_(0) {
  CHECK_EQ(rows.colCount(), target_exprs.size());
  const bool count_first = dynamic_cast<const Analyzer::AggExpr*>(target_exprs[0]);
  for (size_t i = 0; i < truncate_n + 1; ++i) {
    const auto crt_row = rows.getNextRow(false, false);
    if (crt_row.empty()) {
      break;
    }
    int64_t key{0};
    size_t val{0};
    CHECK_EQ(rows.colCount(), crt_row.size());
    {
      auto scalar_r = boost::get<ScalarTargetValue>(&crt_row[0]);
      CHECK(scalar_r);
      auto p = boost::get<int64_t>(scalar_r);
      CHECK(p);
      if (count_first) {
        val = *p;
      } else {
        key = *p;
      }
    }
    {
      auto scalar_r = boost::get<ScalarTargetValue>(&crt_row[1]);
      CHECK(scalar_r);
      auto p = boost::get<int64_t>(scalar_r);
      CHECK(p);
      if (count_first) {
        key = *p;
      } else {
        val = *p;
      }
    }
    if (i < truncate_n) {
      const auto it_ok = map_.emplace(key, SpeculativeTopNVal{val, false});
      CHECK(it_ok.second);
    } else {
      unknown_ = val;
    }
  }
}

Member Function Documentation

std::shared_ptr< ResultSet > SpeculativeTopNMap::asRows	(	const RelAlgExecutionUnit &	ra_exe_unit,
		std::shared_ptr< RowSetMemoryOwner >	row_set_mem_owner,
		const QueryMemoryDescriptor &	query_mem_desc,
		const Executor *	executor,
		const size_t	top_n,
		const bool	desc
	)		const

Definition at line 92 of file SpeculativeTopN.cpp.

References CHECK_EQ, CPU, GroupByBaselineHash, map_, query_mem_desc, gpu_enabled::sort(), gpu_enabled::swap(), RelAlgExecutionUnit::target_exprs, target_exprs_to_infos(), and SpeculativeTopNEntry::val.

Referenced by Executor::reduceSpeculativeTopN().

                           {
  std::vector<SpeculativeTopNEntry> vec;
  for (const auto& kv : map_) {
    vec.emplace_back(SpeculativeTopNEntry{kv.first, kv.second.val, kv.second.unknown});
  }
  if (desc) {
    std::sort(vec.begin(), vec.end(), std::greater<SpeculativeTopNEntry>());
  } else {
    std::sort(vec.begin(), vec.end());
  }
  const auto num_rows = std::min(top_n, vec.size());
  for (size_t i = 0; i < num_rows; ++i) {
    if (vec[i].unknown) {
      throw SpeculativeTopNFailed();
    }
  }
  CHECK_EQ(size_t(2), ra_exe_unit.target_exprs.size());

  // Top N key-value pairs are stored into a new ResultSet with a new
  // QueryMemoryDescriptor to be passed over. We use row-wise GroupByBaselineHash, as it
  // is the most flexible layout for dealing with key-value pairs in the storage (for
  // iterations and reduction).
  auto query_mem_desc_rs = query_mem_desc;
  query_mem_desc_rs.setQueryDescriptionType(QueryDescriptionType::GroupByBaselineHash);
  query_mem_desc_rs.setOutputColumnar(false);
  query_mem_desc_rs.setEntryCount(num_rows);
  query_mem_desc_rs.clearSlotInfo();
  query_mem_desc_rs.addColSlotInfo({std::make_tuple(8, 8)});
  query_mem_desc_rs.addColSlotInfo({std::make_tuple(8, 8)});
  query_mem_desc_rs.setAllTargetGroupbyIndices({-1, -1});

  auto rs = std::make_shared<ResultSet>(
      target_exprs_to_infos(ra_exe_unit.target_exprs, query_mem_desc_rs),
      ExecutorDeviceType::CPU,
      query_mem_desc_rs,
      row_set_mem_owner,
      executor->blockSize(),
      executor->gridSize());
  auto rs_storage = rs->allocateStorage();
  auto rs_buff = reinterpret_cast<int64_t*>(rs_storage->getUnderlyingBuffer());
  const bool count_first =
      dynamic_cast<const Analyzer::AggExpr*>(ra_exe_unit.target_exprs[0]);

  // going throug the TopN results, and properly storing them into the GroupByBaselineHash
  // layout (including the group column (key) and two agg columns (key and value)) to
  // imitate the regular Group By query's result.
  for (size_t i = 0; i < num_rows; ++i) {
    rs_buff[0] = vec[i].key;
    int64_t col0 = vec[i].key;
    int64_t col1 = vec[i].val;
    if (count_first) {
      std::swap(col0, col1);
    }
    rs_buff[1] = col0;
    rs_buff[2] = col1;
    rs_buff += 3;
  }
  return rs;
}

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void SpeculativeTopNMap::reduce

(

SpeculativeTopNMap &

that

)

Definition at line 70 of file SpeculativeTopN.cpp.

References CHECK, map_, unknown_, and SpeculativeTopNVal::val.

Referenced by Executor::reduceSpeculativeTopN().

                                                        {
  for (auto& kv : map_) {
    auto& this_entry = kv.second;
    const auto that_it = that.map_.find(kv.first);
    if (that_it != that.map_.end()) {
      const auto& that_entry = that_it->second;
      CHECK(!that_entry.unknown);
      this_entry.val += that_entry.val;
      that.map_.erase(that_it);
    } else {
      this_entry.val += that.unknown_;
      this_entry.unknown = that.unknown_;
    }
  }
  for (const auto& kv : that.map_) {
    const auto it_ok = map_.emplace(
        kv.first, SpeculativeTopNVal{kv.second.val + unknown_, unknown_ != 0});
    CHECK(it_ok.second);
  }
  unknown_ += that.unknown_;
}

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Member Data Documentation

std::unordered_map<int64_t, SpeculativeTopNVal> SpeculativeTopNMap::map_

private

Definition at line 75 of file SpeculativeTopN.h.

Referenced by asRows(), reduce(), and SpeculativeTopNMap().

size_t SpeculativeTopNMap::unknown_

private

Definition at line 76 of file SpeculativeTopN.h.

Referenced by reduce(), and SpeculativeTopNMap().

---

The documentation for this class was generated from the following files:

• /home/jenkins-slave/workspace/core-os-doxygen/QueryEngine/SpeculativeTopN.h
• /home/jenkins-slave/workspace/core-os-doxygen/QueryEngine/SpeculativeTopN.cpp