Method getOutput

bolt/exec/MergeJoin.cpp:861–956

  // Some, but not all rows passed.
  return wrapAndCombineDict(numPassed, indices, output);
}

RowVectorPtr MergeJoin::getOutput() {
  // Make sure to have is-blocked or needs-input as true if returning null
  // output. Otherwise, Driver assumes the operator is finished.

  // Use Operator::noMoreInput() as a no-more-input-on-the-left indicator and a
  // noMoreRightInput_ flag as no-more-input-on-the-right indicator.

  // TODO Finish early if ran out of data on either side of the join.

  for (;;) {
    auto output = doGetOutput();
    if (output != nullptr && output->size() > 0) {
      if (filter_) {
        output = applyFilter(output);

        if (output != nullptr) {
          for (const auto& [channel, _] : filterInputToOutputChannel_) {
            filterInput_->childAt(channel).reset();
          }
          return output;
        }

        // No rows survived the filter. Get more rows.
        continue;
      } else if (isAntiJoin(joinType_)) {
        output = filterOutputForAntiJoin(output);
        if (output != nullptr && output->size() > 0) {
          return output;
        }

        // No rows survived the filter for anti join. Get more rows.
        continue;
      } else if (
          isLeftSemiFilterJoin(joinType_) || isRightSemiFilterJoin(joinType_)) {
        output = filterOutputForSemiJoin(output);
        if (output != nullptr && output->size() > 0) {
          return output;
        }

        // No rows survived the filter for anti join. Get more rows.
        continue;
      } else {
        return output;
      }
    }

    // Check if we need to get more data from the right side.
    if (!noMoreRightInput_ && !futureRightSideInput_.valid() && !rightInput_) {
      if (!rightSource_) {
        rightSource_ = operatorCtx_->task()->getMergeJoinSource(
            operatorCtx_->driverCtx()->splitGroupId, planNodeId());
      }

      while (!noMoreRightInput_ && !rightInput_) {
        auto blockingReason =