fatemehp commented on code in PR #14142:
URL: https://github.com/apache/arrow/pull/14142#discussion_r1007183618
##########
cpp/src/parquet/column_reader.cc:
##########
@@ -1329,14 +1336,231 @@ class TypedRecordReader : public
ColumnReaderImplBase<DType>,
return records_read;
}
+ // Throw away levels from start_levels_position to levels_position_.
+ // Will update levels_position_, levels_written_, and levels_capacity_
+ // accordingly and move the levels to left to fill in the gap.
+ // It will resize the buffer without releasing the memory allocation.
+ void ThrowAwayLevels(int64_t start_levels_position) {
+ ARROW_DCHECK_LE(levels_position_, levels_written_);
+ ARROW_DCHECK_LE(start_levels_position, levels_position_);
+ ARROW_DCHECK_GT(this->max_def_level_, 0);
+ ARROW_DCHECK_NE(def_levels_, nullptr);
+
+ int64_t gap = levels_position_ - start_levels_position;
+ if (gap == 0) return;
+
+ int64_t levels_remaining = levels_written_ - gap;
+ int64_t destination = levels_position_ - gap;
+
+ auto left_shift = [=](::arrow::ResizableBuffer* buffer) {
+ int16_t* data = reinterpret_cast<int16_t*>(buffer->mutable_data());
+ std::copy(data + levels_position_, data + levels_written_, data +
destination);
+ PARQUET_THROW_NOT_OK(buffer->Resize(levels_remaining * sizeof(int16_t),
+ /*shrink_to_fit=*/false));
+ };
+
+ left_shift(def_levels_.get());
+
+ if (this->max_rep_level_ > 0) {
+ ARROW_DCHECK_NE(rep_levels_, nullptr);
+ left_shift(rep_levels_.get());
+ }
+
+ levels_written_ -= gap;
+ levels_position_ -= gap;
+ levels_capacity_ -= gap;
+ }
+
+ // Skip records that we have in our buffer. This function is only for
+ // non-repeated fields.
+ int64_t SkipRecordsInBufferNonRepeated(int64_t num_records) {
+ ARROW_DCHECK_EQ(this->max_rep_level_, 0);
+ if (!this->has_values_to_process() || num_records == 0) return 0;
+
+ int64_t remaining_records = levels_written_ - levels_position_;
+ int64_t skipped_records = std::min(num_records, remaining_records);
+ int64_t start_levels_position = levels_position_;
+ // Since there is no repetition, number of levels equals number of records.
+ levels_position_ += skipped_records;
+
+ // We skipped the levels by incrementing 'levels_position_'. For values
+ // we do not have a buffer, so we need to read them and throw them away.
+ // First we need to figure out how many present/not-null values there are.
+ std::shared_ptr<::arrow::ResizableBuffer> valid_bits;
+ valid_bits = AllocateBuffer(this->pool_);
+
PARQUET_THROW_NOT_OK(valid_bits->Resize(bit_util::BytesForBits(skipped_records),
+ /*shrink_to_fit=*/true));
+ ValidityBitmapInputOutput validity_io;
+ validity_io.values_read_upper_bound = skipped_records;
+ validity_io.valid_bits = valid_bits->mutable_data();
+ validity_io.valid_bits_offset = 0;
+ DefLevelsToBitmap(def_levels() + start_levels_position, skipped_records,
+ this->leaf_info_, &validity_io);
+ int64_t values_to_read = validity_io.values_read - validity_io.null_count;
+
+ // Now that we have figured out number of values to read, we do not need
+ // these levels anymore. We will remove these values from the buffer.
+ // This requires shifting the levels in the buffer to left. So this will
+ // update levels_position_ and levels_written_.
+ ThrowAwayLevels(start_levels_position);
+ // For values, we do not have them in buffer, so we will read them and
+ // throw them away.
+ ReadAndThrowAwayValues(values_to_read);
Review Comment:
Done, by throwing the error in the function itself as suggested below.
##########
cpp/src/parquet/column_reader.cc:
##########
@@ -1329,14 +1336,231 @@ class TypedRecordReader : public
ColumnReaderImplBase<DType>,
return records_read;
}
+ // Throw away levels from start_levels_position to levels_position_.
+ // Will update levels_position_, levels_written_, and levels_capacity_
+ // accordingly and move the levels to left to fill in the gap.
+ // It will resize the buffer without releasing the memory allocation.
+ void ThrowAwayLevels(int64_t start_levels_position) {
+ ARROW_DCHECK_LE(levels_position_, levels_written_);
+ ARROW_DCHECK_LE(start_levels_position, levels_position_);
+ ARROW_DCHECK_GT(this->max_def_level_, 0);
+ ARROW_DCHECK_NE(def_levels_, nullptr);
+
+ int64_t gap = levels_position_ - start_levels_position;
+ if (gap == 0) return;
+
+ int64_t levels_remaining = levels_written_ - gap;
+ int64_t destination = levels_position_ - gap;
Review Comment:
Done.
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