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Fix length calculation when reading list array with offset #104

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merged 1 commit into from
Aug 15, 2022
Merged

Fix length calculation when reading list array with offset #104

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32 changes: 20 additions & 12 deletions cpp/src/lance/io/reader.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -299,11 +299,15 @@ ::arrow::Result<std::shared_ptr<::arrow::Array>> FileReader::GetArray(
storage_arr = GetPrimitiveArray(field, batch_id, params);
}

if (!storage_arr.ok()) {
return storage_arr;
}

if (field->is_extension_type()) {
std::shared_ptr<::arrow::ExtensionType> ext_type = ::arrow::GetExtensionType(
field->extension_name());
std::shared_ptr<::arrow::ExtensionType> ext_type =
::arrow::GetExtensionType(field->extension_name());
if (ext_type != nullptr && storage_arr.ok()) {
return ::arrow::ExtensionType::WrapArray(ext_type, storage_arr.ValueOrDie());
return ::arrow::ExtensionType::WrapArray(ext_type, storage_arr.ValueOrDie());
}
}
return storage_arr;
Expand Down Expand Up @@ -335,11 +339,15 @@ ::arrow::Result<std::shared_ptr<::arrow::Array>> FileReader::GetListArray(
"FileReader::GetListArray: indices is empty: field={}({})", field->name(), field->id()));
}
auto start = static_cast<int32_t>(indices->Value(0));
auto length = static_cast<int32_t>(indices->Value(indices->length() - 1) - start);
auto length = static_cast<int32_t>(indices->Value(indices->length() - 1) - start + 1);

ARROW_ASSIGN_OR_RAISE(auto unfiltered_arr,
GetListArray(field, batch_id, ArrayReadParams(start, length)));
ARROW_ASSIGN_OR_RAISE(auto datum,
::arrow::compute::CallFunction("take", {unfiltered_arr, indices}));
ARROW_ASSIGN_OR_RAISE(auto offsets_datum,
::arrow::compute::Subtract(indices, ::arrow::Datum(indices->Value(0))));
ARROW_ASSIGN_OR_RAISE(
auto datum,
::arrow::compute::CallFunction("take", {unfiltered_arr, offsets_datum.make_array()}));
return datum.make_array();
}

Expand All @@ -363,10 +371,11 @@ ::arrow::Result<std::shared_ptr<::arrow::Array>> FileReader::GetListArray(
// Realigned offsets to be zero-started
ARROW_ASSIGN_OR_RAISE(auto shifted_offsets, ResetOffsets(offsets));
// Setup null bitmap
ARROW_ASSIGN_OR_RAISE(auto null_bitmap, ::arrow::AllocateBitmap(shifted_offsets->length() - 1, pool_));
ARROW_ASSIGN_OR_RAISE(auto null_bitmap,
::arrow::AllocateBitmap(shifted_offsets->length() - 1, pool_));
for (int i = 0; i < shifted_offsets->length() - 1; i++) {
::arrow::bit_util::SetBitTo(null_bitmap->mutable_data(), i,
offsets->Value(i + 1) - offsets->Value(i) > 0);
::arrow::bit_util::SetBitTo(
null_bitmap->mutable_data(), i, offsets->Value(i + 1) - offsets->Value(i) > 0);
}
return std::make_shared<::arrow::ListArray>(field->type(),
shifted_offsets->length() - 1,
Expand Down Expand Up @@ -394,11 +403,10 @@ ::arrow::Result<std::shared_ptr<::arrow::Array>> FileReader::GetPrimitiveArray(
decoder->Reset(position, length);
decltype(decoder->ToArray()) result;
if (params.indices) {
result = decoder->Take(params.indices.value());
return decoder->Take(params.indices.value());
} else {
result = decoder->ToArray(params.offset.value(), params.length);
return decoder->ToArray(params.offset.value(), params.length);
}
return result;
}

FileReader::ArrayReadParams::ArrayReadParams(int32_t off, std::optional<int32_t> len)
Expand Down
36 changes: 36 additions & 0 deletions cpp/src/lance/io/reader_test.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@
#include "lance/arrow/stl.h"
#include "lance/arrow/type.h"
#include "lance/arrow/writer.h"
#include "lance/io/reader.h"

TEST_CASE("Test List Array With Nulls") {
auto int_builder = std::make_shared<::arrow::Int32Builder>();
Expand Down Expand Up @@ -64,3 +65,38 @@ TEST_CASE("Test List Array With Nulls") {
CHECK(scalar->Equals(::arrow::NullScalar()));
}
}

TEST_CASE("Get List Array With Indices") {
auto value_builder = std::make_shared<::arrow::Int32Builder>();
auto list_builder = ::arrow::ListBuilder(::arrow::default_memory_pool(), value_builder);
for (int i = 0; i < 10; i++) {
CHECK(list_builder.Append().ok());
CHECK(value_builder->AppendValues({1 * i, 2 * i, 3 * i}).ok());
}

auto arr = std::static_pointer_cast<::arrow::ListArray>(list_builder.Finish().ValueOrDie());
auto schema = ::arrow::schema({::arrow::field("values", ::arrow::list(::arrow::int32()))});
auto table = ::arrow::Table::Make(schema, {arr});

auto sink = arrow::io::BufferOutputStream::Create().ValueOrDie();
CHECK(lance::arrow::WriteTable(*table, sink).ok());
auto infile = make_shared<arrow::io::BufferReader>(sink->Finish().ValueOrDie());
auto reader = lance::io::FileReader(infile);
CHECK(reader.Open().ok());

for (auto& indices : std::vector<std::vector<int>>({{0, 1, 3}, {2, 3, 4}, {0, 5, 9}})) {
list_builder.Reset();
value_builder->Reset();
for (int idx : indices) {
CHECK(list_builder.Append().ok());
CHECK(value_builder->AppendValues({idx * 1, idx * 2, idx * 3}).ok());
}
auto expected_arr =
std::static_pointer_cast<::arrow::ListArray>(list_builder.Finish().ValueOrDie());
auto expected_table = ::arrow::Table::Make(schema, {expected_arr});

auto batch = reader.ReadBatch(reader.schema(), 0, lance::arrow::ToArray(indices).ValueOrDie())
.ValueOrDie();
CHECK(batch->Equals(*expected_table->CombineChunksToBatch().ValueOrDie()));
}
}