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JoinFilterPushDown.cpp File Reference
#include "JoinFilterPushDown.h"
#include "DeepCopyVisitor.h"
#include "RelAlgExecutor.h"
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Classes

class  anonymous_namespace{JoinFilterPushDown.cpp}::BindFilterToOutermostVisitor
 
class  anonymous_namespace{JoinFilterPushDown.cpp}::CollectInputColumnsVisitor
 

Namespaces

 anonymous_namespace{JoinFilterPushDown.cpp}
 

Functions

bool to_gather_info_for_filter_selectivity (const std::vector< InputTableInfo > &table_infos)
 
std::vector< PushedDownFilterInfofind_push_down_filters (const RelAlgExecutionUnit &ra_exe_unit, const std::vector< size_t > &input_permutation, const std::vector< size_t > &left_deep_join_input_sizes)
 

Function Documentation

std::vector<PushedDownFilterInfo> find_push_down_filters ( const RelAlgExecutionUnit ra_exe_unit,
const std::vector< size_t > &  input_permutation,
const std::vector< size_t > &  left_deep_join_input_sizes 
)

Go through all tables involved in the relational algebra plan, and select potential candidates to be pushed down by calcite. For each filter we store a set of intermediate indices (previous, current, and next table) based on the column indices in their query string.

Definition at line 241 of file JoinFilterPushDown.cpp.

References CHECK_EQ, CHECK_GE, CHECK_LT, RelAlgExecutionUnit::input_descs, RelAlgExecutionUnit::join_quals, run_benchmark_import::result, and ScalarExprVisitor< T >::visit().

Referenced by RelAlgExecutor::selectFiltersToBePushedDown().

244  {
245  std::vector<PushedDownFilterInfo> result;
246  if (left_deep_join_input_sizes.empty()) {
247  return result;
248  }
249  std::vector<size_t> input_size_prefix_sums(left_deep_join_input_sizes.size());
250  std::partial_sum(left_deep_join_input_sizes.begin(),
251  left_deep_join_input_sizes.end(),
252  input_size_prefix_sums.begin());
253  std::vector<int> to_original_rte_idx(ra_exe_unit.input_descs.size(),
254  ra_exe_unit.input_descs.size());
255  if (!input_permutation.empty()) {
256  CHECK_EQ(to_original_rte_idx.size(), input_permutation.size());
257  for (size_t i = 0; i < input_permutation.size(); ++i) {
258  CHECK_LT(input_permutation[i], to_original_rte_idx.size());
259  CHECK_EQ(static_cast<size_t>(to_original_rte_idx[input_permutation[i]]),
260  to_original_rte_idx.size());
261  to_original_rte_idx[input_permutation[i]] = i;
262  }
263  } else {
264  std::iota(to_original_rte_idx.begin(), to_original_rte_idx.end(), 0);
265  }
266  std::unordered_map<int, std::vector<std::shared_ptr<Analyzer::Expr>>>
267  filters_per_nesting_level;
268  for (const auto& level_conditions : ra_exe_unit.join_quals) {
270  for (const auto& cond : level_conditions.quals) {
271  const auto rte_indices = visitor.visit(cond.get());
272  if (rte_indices.size() > 1) {
273  continue;
274  }
275  const int rte_idx = (!rte_indices.empty()) ? *rte_indices.cbegin() : 0;
276  if (!rte_idx) {
277  continue;
278  }
279  CHECK_GE(rte_idx, 0);
280  CHECK_LT(static_cast<size_t>(rte_idx), to_original_rte_idx.size());
281  filters_per_nesting_level[to_original_rte_idx[rte_idx]].push_back(cond);
282  }
283  }
284  for (const auto& kv : filters_per_nesting_level) {
285  CHECK_GE(kv.first, 0);
286  CHECK_LT(static_cast<size_t>(kv.first), input_size_prefix_sums.size());
287  size_t input_prev = (kv.first > 1) ? input_size_prefix_sums[kv.first - 2] : 0;
288  size_t input_start = kv.first ? input_size_prefix_sums[kv.first - 1] : 0;
289  size_t input_next = input_size_prefix_sums[kv.first];
290  result.emplace_back(
291  PushedDownFilterInfo{kv.second, input_prev, input_start, input_next});
292  }
293  return result;
294 }
#define CHECK_EQ(x, y)
Definition: Logger.h:205
std::vector< InputDescriptor > input_descs
#define CHECK_GE(x, y)
Definition: Logger.h:210
T visit(const Analyzer::Expr *expr) const
const JoinQualsPerNestingLevel join_quals
#define CHECK_LT(x, y)
Definition: Logger.h:207

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bool to_gather_info_for_filter_selectivity ( const std::vector< InputTableInfo > &  table_infos)

The main purpose of this function is to prevent going through extra overhead of computing required statistics for finding the right candidates and then the actual push-down, unless the problem is large enough that such effort is potentially helpful.

Definition at line 214 of file JoinFilterPushDown.cpp.

Referenced by RelAlgExecutor::selectFiltersToBePushedDown().

215  {
216  if (table_infos.size() < 2) {
217  return false;
218  }
219  // we currently do not support filter push down when there is a self-join involved:
220  // TODO(Saman): prevent Calcite from optimizing self-joins to remove this exclusion
221  std::unordered_set<int> table_ids;
222  for (auto ti : table_infos) {
223  if (table_ids.find(ti.table_id) == table_ids.end()) {
224  table_ids.insert(ti.table_id);
225  } else {
226  // a self-join is involved
227  return false;
228  }
229  }
230  // TODO(Saman): add some extra heuristics to avoid preflight count and push down if it
231  // is not going to be helpful.
232  return true;
233 }

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