Method canPushdownFilters

bolt/exec/Driver.cpp:1005–1052

}

std::unordered_set<column_index_t> Driver::canPushdownFilters(
    const Operator* filterSource,
    const std::vector<column_index_t>& channels) const {
  int filterSourceIndex = -1;
  for (auto i = 0; i < operators_.size(); ++i) {
    auto op = operators_[i].get();
    if (filterSource == op) {
      filterSourceIndex = i;
      break;
    }
  }
  BOLT_CHECK_GE(
      filterSourceIndex,
      0,
      "Operator not found in its Driver: {}",
      filterSource->toString());

  std::unordered_set<column_index_t> supportedChannels;
  for (auto i = 0; i < channels.size(); ++i) {
    auto channel = channels[i];
    for (auto j = filterSourceIndex - 1; j >= 0; --j) {
      auto prevOp = operators_[j].get();

      if (j == 0) {
        // Source operator.
        if (prevOp->canAddDynamicFilter()) {
          supportedChannels.emplace(channels[i]);
        }
        break;
      }

      const auto& identityProjections = prevOp->identityProjections();
      auto inputChannel = getIdentityProjection(identityProjections, channel);
      if (!inputChannel.has_value()) {
        // Filter channel is not an identity projection.
        if (prevOp->canAddDynamicFilter()) {
          supportedChannels.emplace(channels[i]);
        }
        break;
      }

      // Continue walking upstream.
      channel = inputChannel.value();
    }
  }

  return supportedChannels;
}

Operator* Driver::findOperator(std::string_view planNodeId) const {
  for (auto& op : operators_) {