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schema.cc
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schema.cc
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// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
#include "parquet/arrow/schema.h"
#include <functional>
#include <string>
#include <vector>
#include "arrow/extension_type.h"
#include "arrow/io/memory.h"
#include "arrow/ipc/api.h"
#include "arrow/result_internal.h"
#include "arrow/type.h"
#include "arrow/util/base64.h"
#include "arrow/util/checked_cast.h"
#include "arrow/util/key_value_metadata.h"
#include "arrow/util/logging.h"
#include "arrow/util/string.h"
#include "arrow/util/value_parsing.h"
#include "parquet/arrow/schema_internal.h"
#include "parquet/exception.h"
#include "parquet/metadata.h"
#include "parquet/properties.h"
#include "parquet/types.h"
using arrow::DecimalType;
using arrow::Field;
using arrow::FieldVector;
using arrow::KeyValueMetadata;
using arrow::Status;
using arrow::internal::checked_cast;
using arrow::internal::EndsWith;
using arrow::internal::ToChars;
using ArrowType = arrow::DataType;
using ArrowTypeId = arrow::Type;
using parquet::Repetition;
using parquet::schema::GroupNode;
using parquet::schema::Node;
using parquet::schema::NodePtr;
using parquet::schema::PrimitiveNode;
using ParquetType = parquet::Type;
using parquet::ConvertedType;
using parquet::LogicalType;
using parquet::internal::LevelInfo;
namespace parquet::arrow {
// ----------------------------------------------------------------------
// Parquet to Arrow schema conversion
namespace {
Repetition::type RepetitionFromNullable(bool is_nullable) {
return is_nullable ? Repetition::OPTIONAL : Repetition::REQUIRED;
}
Status FieldToNode(const std::string& name, const std::shared_ptr<Field>& field,
const WriterProperties& properties,
const ArrowWriterProperties& arrow_properties, NodePtr* out);
Status ListToNode(const std::shared_ptr<::arrow::BaseListType>& type,
const std::string& name, bool nullable, int field_id,
const WriterProperties& properties,
const ArrowWriterProperties& arrow_properties, NodePtr* out) {
NodePtr element;
std::string value_name =
arrow_properties.compliant_nested_types() ? "element" : type->value_field()->name();
RETURN_NOT_OK(FieldToNode(value_name, type->value_field(), properties, arrow_properties,
&element));
NodePtr list = GroupNode::Make("list", Repetition::REPEATED, {element});
*out = GroupNode::Make(name, RepetitionFromNullable(nullable), {list},
LogicalType::List(), field_id);
return Status::OK();
}
Status MapToNode(const std::shared_ptr<::arrow::MapType>& type, const std::string& name,
bool nullable, int field_id, const WriterProperties& properties,
const ArrowWriterProperties& arrow_properties, NodePtr* out) {
// TODO: Should we offer a non-compliant mode that forwards the type names?
NodePtr key_node;
RETURN_NOT_OK(
FieldToNode("key", type->key_field(), properties, arrow_properties, &key_node));
NodePtr value_node;
RETURN_NOT_OK(FieldToNode("value", type->item_field(), properties, arrow_properties,
&value_node));
NodePtr key_value =
GroupNode::Make("key_value", Repetition::REPEATED, {key_node, value_node});
*out = GroupNode::Make(name, RepetitionFromNullable(nullable), {key_value},
LogicalType::Map(), field_id);
return Status::OK();
}
Status StructToNode(const std::shared_ptr<::arrow::StructType>& type,
const std::string& name, bool nullable, int field_id,
const WriterProperties& properties,
const ArrowWriterProperties& arrow_properties, NodePtr* out) {
std::vector<NodePtr> children(type->num_fields());
if (type->num_fields() != 0) {
for (int i = 0; i < type->num_fields(); i++) {
RETURN_NOT_OK(FieldToNode(type->field(i)->name(), type->field(i), properties,
arrow_properties, &children[i]));
}
} else {
// XXX (ARROW-10928) We could add a dummy primitive node but that would
// require special handling when writing and reading, to avoid column index
// mismatches.
return Status::NotImplemented("Cannot write struct type '", name,
"' with no child field to Parquet. "
"Consider adding a dummy child field.");
}
*out = GroupNode::Make(name, RepetitionFromNullable(nullable), children, nullptr,
field_id);
return Status::OK();
}
static std::shared_ptr<const LogicalType> TimestampLogicalTypeFromArrowTimestamp(
const ::arrow::TimestampType& timestamp_type, ::arrow::TimeUnit::type time_unit) {
const bool utc = !(timestamp_type.timezone().empty());
// ARROW-5878(wesm): for forward compatibility reasons, and because
// there's no other way to signal to old readers that values are
// timestamps, we force the ConvertedType field to be set to the
// corresponding TIMESTAMP_* value. This does cause some ambiguity
// as Parquet readers have not been consistent about the
// interpretation of TIMESTAMP_* values as being UTC-normalized.
switch (time_unit) {
case ::arrow::TimeUnit::MILLI:
return LogicalType::Timestamp(utc, LogicalType::TimeUnit::MILLIS,
/*is_from_converted_type=*/false,
/*force_set_converted_type=*/true);
case ::arrow::TimeUnit::MICRO:
return LogicalType::Timestamp(utc, LogicalType::TimeUnit::MICROS,
/*is_from_converted_type=*/false,
/*force_set_converted_type=*/true);
case ::arrow::TimeUnit::NANO:
return LogicalType::Timestamp(utc, LogicalType::TimeUnit::NANOS,
/*is_from_converted_type=*/false,
/*force_set_converted_type=*/false);
case ::arrow::TimeUnit::SECOND:
// No equivalent parquet logical type.
break;
}
return LogicalType::None();
}
static Status GetTimestampMetadata(const ::arrow::TimestampType& type,
const WriterProperties& properties,
const ArrowWriterProperties& arrow_properties,
ParquetType::type* physical_type,
std::shared_ptr<const LogicalType>* logical_type) {
const bool coerce = arrow_properties.coerce_timestamps_enabled();
const auto target_unit =
coerce ? arrow_properties.coerce_timestamps_unit() : type.unit();
const auto version = properties.version();
// The user is explicitly asking for Impala int96 encoding, there is no
// logical type.
if (arrow_properties.support_deprecated_int96_timestamps()) {
*physical_type = ParquetType::INT96;
return Status::OK();
}
*physical_type = ParquetType::INT64;
*logical_type = TimestampLogicalTypeFromArrowTimestamp(type, target_unit);
// The user is explicitly asking for timestamp data to be converted to the
// specified units (target_unit).
if (coerce) {
if (version == ::parquet::ParquetVersion::PARQUET_1_0 ||
version == ::parquet::ParquetVersion::PARQUET_2_4) {
switch (target_unit) {
case ::arrow::TimeUnit::MILLI:
case ::arrow::TimeUnit::MICRO:
break;
case ::arrow::TimeUnit::NANO:
case ::arrow::TimeUnit::SECOND:
return Status::NotImplemented("For Parquet version ",
::parquet::ParquetVersionToString(version),
", can only coerce Arrow timestamps to "
"milliseconds or microseconds");
}
} else {
switch (target_unit) {
case ::arrow::TimeUnit::MILLI:
case ::arrow::TimeUnit::MICRO:
case ::arrow::TimeUnit::NANO:
break;
case ::arrow::TimeUnit::SECOND:
return Status::NotImplemented("For Parquet version ",
::parquet::ParquetVersionToString(version),
", can only coerce Arrow timestamps to "
"milliseconds, microseconds, or nanoseconds");
}
}
return Status::OK();
}
// The user implicitly wants timestamp data to retain its original time units,
// however the ConvertedType field used to indicate logical types for Parquet
// version <= 2.4 fields does not allow for nanosecond time units and so nanoseconds
// must be coerced to microseconds.
if ((version == ::parquet::ParquetVersion::PARQUET_1_0 ||
version == ::parquet::ParquetVersion::PARQUET_2_4) &&
type.unit() == ::arrow::TimeUnit::NANO) {
*logical_type =
TimestampLogicalTypeFromArrowTimestamp(type, ::arrow::TimeUnit::MICRO);
return Status::OK();
}
// The user implicitly wants timestamp data to retain its original time units,
// however the Arrow seconds time unit cannot be represented (annotated) in
// any version of Parquet and so must be coerced to milliseconds.
if (type.unit() == ::arrow::TimeUnit::SECOND) {
*logical_type =
TimestampLogicalTypeFromArrowTimestamp(type, ::arrow::TimeUnit::MILLI);
return Status::OK();
}
return Status::OK();
}
static constexpr char FIELD_ID_KEY[] = "PARQUET:field_id";
std::shared_ptr<::arrow::KeyValueMetadata> FieldIdMetadata(int field_id) {
if (field_id >= 0) {
return ::arrow::key_value_metadata({FIELD_ID_KEY}, {ToChars(field_id)});
} else {
return nullptr;
}
}
int FieldIdFromMetadata(
const std::shared_ptr<const ::arrow::KeyValueMetadata>& metadata) {
if (!metadata) {
return -1;
}
int key = metadata->FindKey(FIELD_ID_KEY);
if (key < 0) {
return -1;
}
std::string field_id_str = metadata->value(key);
int field_id;
if (::arrow::internal::ParseValue<::arrow::Int32Type>(
field_id_str.c_str(), field_id_str.length(), &field_id)) {
if (field_id < 0) {
// Thrift should convert any negative value to null but normalize to -1 here in case
// we later check this in logic.
return -1;
}
return field_id;
} else {
return -1;
}
}
Status FieldToNode(const std::string& name, const std::shared_ptr<Field>& field,
const WriterProperties& properties,
const ArrowWriterProperties& arrow_properties, NodePtr* out) {
std::shared_ptr<const LogicalType> logical_type = LogicalType::None();
ParquetType::type type;
Repetition::type repetition = RepetitionFromNullable(field->nullable());
int field_id = FieldIdFromMetadata(field->metadata());
int length = -1;
int precision = -1;
int scale = -1;
switch (field->type()->id()) {
case ArrowTypeId::NA: {
type = ParquetType::INT32;
logical_type = LogicalType::Null();
if (repetition != Repetition::OPTIONAL) {
return Status::Invalid("NullType Arrow field must be nullable");
}
} break;
case ArrowTypeId::BOOL:
type = ParquetType::BOOLEAN;
break;
case ArrowTypeId::UINT8:
type = ParquetType::INT32;
logical_type = LogicalType::Int(8, false);
break;
case ArrowTypeId::INT8:
type = ParquetType::INT32;
logical_type = LogicalType::Int(8, true);
break;
case ArrowTypeId::UINT16:
type = ParquetType::INT32;
logical_type = LogicalType::Int(16, false);
break;
case ArrowTypeId::INT16:
type = ParquetType::INT32;
logical_type = LogicalType::Int(16, true);
break;
case ArrowTypeId::UINT32:
if (properties.version() == ::parquet::ParquetVersion::PARQUET_1_0) {
type = ParquetType::INT64;
} else {
type = ParquetType::INT32;
logical_type = LogicalType::Int(32, false);
}
break;
case ArrowTypeId::INT32:
type = ParquetType::INT32;
break;
case ArrowTypeId::UINT64:
type = ParquetType::INT64;
logical_type = LogicalType::Int(64, false);
break;
case ArrowTypeId::INT64:
type = ParquetType::INT64;
break;
case ArrowTypeId::FLOAT:
type = ParquetType::FLOAT;
break;
case ArrowTypeId::DOUBLE:
type = ParquetType::DOUBLE;
break;
case ArrowTypeId::LARGE_STRING:
case ArrowTypeId::STRING:
type = ParquetType::BYTE_ARRAY;
logical_type = LogicalType::String();
break;
case ArrowTypeId::LARGE_BINARY:
case ArrowTypeId::BINARY:
type = ParquetType::BYTE_ARRAY;
break;
case ArrowTypeId::FIXED_SIZE_BINARY: {
type = ParquetType::FIXED_LEN_BYTE_ARRAY;
const auto& fixed_size_binary_type =
static_cast<const ::arrow::FixedSizeBinaryType&>(*field->type());
length = fixed_size_binary_type.byte_width();
} break;
case ArrowTypeId::DECIMAL128:
case ArrowTypeId::DECIMAL256: {
const auto& decimal_type = static_cast<const ::arrow::DecimalType&>(*field->type());
precision = decimal_type.precision();
scale = decimal_type.scale();
if (properties.store_decimal_as_integer() && 1 <= precision && precision <= 18) {
type = precision <= 9 ? ParquetType ::INT32 : ParquetType ::INT64;
} else {
type = ParquetType::FIXED_LEN_BYTE_ARRAY;
length = DecimalType::DecimalSize(precision);
}
PARQUET_CATCH_NOT_OK(logical_type = LogicalType::Decimal(precision, scale));
} break;
case ArrowTypeId::DATE32:
type = ParquetType::INT32;
logical_type = LogicalType::Date();
break;
case ArrowTypeId::DATE64:
type = ParquetType::INT32;
logical_type = LogicalType::Date();
break;
case ArrowTypeId::TIMESTAMP:
RETURN_NOT_OK(
GetTimestampMetadata(static_cast<::arrow::TimestampType&>(*field->type()),
properties, arrow_properties, &type, &logical_type));
break;
case ArrowTypeId::TIME32:
type = ParquetType::INT32;
logical_type =
LogicalType::Time(/*is_adjusted_to_utc=*/true, LogicalType::TimeUnit::MILLIS);
break;
case ArrowTypeId::TIME64: {
type = ParquetType::INT64;
auto time_type = static_cast<::arrow::Time64Type*>(field->type().get());
if (time_type->unit() == ::arrow::TimeUnit::NANO) {
logical_type =
LogicalType::Time(/*is_adjusted_to_utc=*/true, LogicalType::TimeUnit::NANOS);
} else {
logical_type =
LogicalType::Time(/*is_adjusted_to_utc=*/true, LogicalType::TimeUnit::MICROS);
}
} break;
case ArrowTypeId::DURATION:
type = ParquetType::INT64;
break;
case ArrowTypeId::HALF_FLOAT:
type = ParquetType::FIXED_LEN_BYTE_ARRAY;
logical_type = LogicalType::Float16();
length = sizeof(uint16_t);
break;
case ArrowTypeId::STRUCT: {
auto struct_type = std::static_pointer_cast<::arrow::StructType>(field->type());
return StructToNode(struct_type, name, field->nullable(), field_id, properties,
arrow_properties, out);
}
case ArrowTypeId::FIXED_SIZE_LIST:
case ArrowTypeId::LARGE_LIST:
case ArrowTypeId::LIST: {
auto list_type = std::static_pointer_cast<::arrow::BaseListType>(field->type());
return ListToNode(list_type, name, field->nullable(), field_id, properties,
arrow_properties, out);
}
case ArrowTypeId::DICTIONARY: {
// Parquet has no Dictionary type, dictionary-encoded is handled on
// the encoding, not the schema level.
const ::arrow::DictionaryType& dict_type =
static_cast<const ::arrow::DictionaryType&>(*field->type());
std::shared_ptr<::arrow::Field> unpacked_field = ::arrow::field(
name, dict_type.value_type(), field->nullable(), field->metadata());
return FieldToNode(name, unpacked_field, properties, arrow_properties, out);
}
case ArrowTypeId::EXTENSION: {
auto ext_type = std::static_pointer_cast<::arrow::ExtensionType>(field->type());
std::shared_ptr<::arrow::Field> storage_field = ::arrow::field(
name, ext_type->storage_type(), field->nullable(), field->metadata());
return FieldToNode(name, storage_field, properties, arrow_properties, out);
}
case ArrowTypeId::MAP: {
auto map_type = std::static_pointer_cast<::arrow::MapType>(field->type());
return MapToNode(map_type, name, field->nullable(), field_id, properties,
arrow_properties, out);
}
default: {
// TODO: DENSE_UNION, SPARE_UNION, JSON_SCALAR, DECIMAL_TEXT, VARCHAR
return Status::NotImplemented(
"Unhandled type for Arrow to Parquet schema conversion: ",
field->type()->ToString());
}
}
PARQUET_CATCH_NOT_OK(*out = PrimitiveNode::Make(name, repetition, logical_type, type,
length, field_id));
return Status::OK();
}
struct SchemaTreeContext {
SchemaManifest* manifest;
ArrowReaderProperties properties;
const SchemaDescriptor* schema;
void LinkParent(const SchemaField* child, const SchemaField* parent) {
manifest->child_to_parent[child] = parent;
}
void RecordLeaf(const SchemaField* leaf) {
manifest->column_index_to_field[leaf->column_index] = leaf;
}
};
bool IsDictionaryReadSupported(const ArrowType& type) {
// Only supported currently for BYTE_ARRAY types
return type.id() == ::arrow::Type::BINARY || type.id() == ::arrow::Type::STRING;
}
// ----------------------------------------------------------------------
// Schema logic
::arrow::Result<std::shared_ptr<ArrowType>> GetTypeForNode(
int column_index, const schema::PrimitiveNode& primitive_node,
SchemaTreeContext* ctx) {
ASSIGN_OR_RAISE(
std::shared_ptr<ArrowType> storage_type,
GetArrowType(primitive_node, ctx->properties.coerce_int96_timestamp_unit()));
if (ctx->properties.read_dictionary(column_index) &&
IsDictionaryReadSupported(*storage_type)) {
return ::arrow::dictionary(::arrow::int32(), storage_type);
}
return storage_type;
}
Status NodeToSchemaField(const Node& node, LevelInfo current_levels,
SchemaTreeContext* ctx, const SchemaField* parent,
SchemaField* out);
Status GroupToSchemaField(const GroupNode& node, LevelInfo current_levels,
SchemaTreeContext* ctx, const SchemaField* parent,
SchemaField* out);
Status PopulateLeaf(int column_index, const std::shared_ptr<Field>& field,
LevelInfo current_levels, SchemaTreeContext* ctx,
const SchemaField* parent, SchemaField* out) {
out->field = field;
out->column_index = column_index;
out->level_info = current_levels;
ctx->RecordLeaf(out);
ctx->LinkParent(out, parent);
return Status::OK();
}
// Special case mentioned in the format spec:
// If the name is array or ends in _tuple, this should be a list of struct
// even for single child elements.
bool HasStructListName(const GroupNode& node) {
::std::string_view name{node.name()};
return name == "array" || EndsWith(name, "_tuple");
}
Status GroupToStruct(const GroupNode& node, LevelInfo current_levels,
SchemaTreeContext* ctx, const SchemaField* parent,
SchemaField* out) {
std::vector<std::shared_ptr<Field>> arrow_fields;
out->children.resize(node.field_count());
// All level increments for the node are expected to happen by callers.
// This is required because repeated elements need to have their own
// SchemaField.
for (int i = 0; i < node.field_count(); i++) {
RETURN_NOT_OK(
NodeToSchemaField(*node.field(i), current_levels, ctx, out, &out->children[i]));
arrow_fields.push_back(out->children[i].field);
}
auto struct_type = ::arrow::struct_(arrow_fields);
out->field = ::arrow::field(node.name(), struct_type, node.is_optional(),
FieldIdMetadata(node.field_id()));
out->level_info = current_levels;
return Status::OK();
}
Status ListToSchemaField(const GroupNode& group, LevelInfo current_levels,
SchemaTreeContext* ctx, const SchemaField* parent,
SchemaField* out);
Status MapToSchemaField(const GroupNode& group, LevelInfo current_levels,
SchemaTreeContext* ctx, const SchemaField* parent,
SchemaField* out) {
if (group.field_count() != 1) {
return Status::Invalid("MAP-annotated groups must have a single child.");
}
if (group.is_repeated()) {
return Status::Invalid("MAP-annotated groups must not be repeated.");
}
const Node& key_value_node = *group.field(0);
if (!key_value_node.is_repeated()) {
return Status::Invalid(
"Non-repeated key value in a MAP-annotated group are not supported.");
}
if (!key_value_node.is_group()) {
return Status::Invalid("Key-value node must be a group.");
}
const GroupNode& key_value = checked_cast<const GroupNode&>(key_value_node);
if (key_value.field_count() != 1 && key_value.field_count() != 2) {
return Status::Invalid("Key-value map node must have 1 or 2 child elements. Found: ",
key_value.field_count());
}
const Node& key_node = *key_value.field(0);
if (!key_node.is_required()) {
return Status::Invalid("Map keys must be annotated as required.");
}
// Arrow doesn't support 1 column maps (i.e. Sets). The options are to either
// make the values column nullable, or process the map as a list. We choose the latter
// as it is simpler.
if (key_value.field_count() == 1) {
return ListToSchemaField(group, current_levels, ctx, parent, out);
}
current_levels.Increment(group);
int16_t repeated_ancestor_def_level = current_levels.IncrementRepeated();
out->children.resize(1);
SchemaField* key_value_field = &out->children[0];
key_value_field->children.resize(2);
SchemaField* key_field = &key_value_field->children[0];
SchemaField* value_field = &key_value_field->children[1];
ctx->LinkParent(out, parent);
ctx->LinkParent(key_value_field, out);
ctx->LinkParent(key_field, key_value_field);
ctx->LinkParent(value_field, key_value_field);
// required/optional group name=whatever {
// repeated group name=key_values{
// required TYPE key;
// required/optional TYPE value;
// }
// }
//
RETURN_NOT_OK(NodeToSchemaField(*key_value.field(0), current_levels, ctx,
key_value_field, key_field));
RETURN_NOT_OK(NodeToSchemaField(*key_value.field(1), current_levels, ctx,
key_value_field, value_field));
key_value_field->field = ::arrow::field(
group.name(), ::arrow::struct_({key_field->field, value_field->field}),
/*nullable=*/false, FieldIdMetadata(key_value.field_id()));
key_value_field->level_info = current_levels;
out->field = ::arrow::field(group.name(),
std::make_shared<::arrow::MapType>(key_value_field->field),
group.is_optional(), FieldIdMetadata(group.field_id()));
out->level_info = current_levels;
// At this point current levels contains the def level for this list,
// we need to reset to the prior parent.
out->level_info.repeated_ancestor_def_level = repeated_ancestor_def_level;
return Status::OK();
}
Status ListToSchemaField(const GroupNode& group, LevelInfo current_levels,
SchemaTreeContext* ctx, const SchemaField* parent,
SchemaField* out) {
if (group.field_count() != 1) {
return Status::Invalid("LIST-annotated groups must have a single child.");
}
if (group.is_repeated()) {
return Status::Invalid("LIST-annotated groups must not be repeated.");
}
current_levels.Increment(group);
out->children.resize(group.field_count());
SchemaField* child_field = &out->children[0];
ctx->LinkParent(out, parent);
ctx->LinkParent(child_field, out);
const Node& list_node = *group.field(0);
if (!list_node.is_repeated()) {
return Status::Invalid(
"Non-repeated nodes in a LIST-annotated group are not supported.");
}
int16_t repeated_ancestor_def_level = current_levels.IncrementRepeated();
if (list_node.is_group()) {
// Resolve 3-level encoding
//
// required/optional group name=whatever {
// repeated group name=list {
// required/optional TYPE item;
// }
// }
//
// yields list<item: TYPE ?nullable> ?nullable
//
// We distinguish the special case that we have
//
// required/optional group name=whatever {
// repeated group name=array or $SOMETHING_tuple {
// required/optional TYPE item;
// }
// }
//
// In this latter case, the inner type of the list should be a struct
// rather than a primitive value
//
// yields list<item: struct<item: TYPE ?nullable> not null> ?nullable
const auto& list_group = static_cast<const GroupNode&>(list_node);
// Special case mentioned in the format spec:
// If the name is array or ends in _tuple, this should be a list of struct
// even for single child elements.
if (list_group.field_count() == 1 && !HasStructListName(list_group)) {
// List of primitive type
RETURN_NOT_OK(
NodeToSchemaField(*list_group.field(0), current_levels, ctx, out, child_field));
} else {
RETURN_NOT_OK(GroupToStruct(list_group, current_levels, ctx, out, child_field));
}
} else {
// Two-level list encoding
//
// required/optional group LIST {
// repeated TYPE;
// }
const auto& primitive_node = static_cast<const PrimitiveNode&>(list_node);
int column_index = ctx->schema->GetColumnIndex(primitive_node);
ASSIGN_OR_RAISE(std::shared_ptr<ArrowType> type,
GetTypeForNode(column_index, primitive_node, ctx));
auto item_field = ::arrow::field(list_node.name(), type, /*nullable=*/false,
FieldIdMetadata(list_node.field_id()));
RETURN_NOT_OK(
PopulateLeaf(column_index, item_field, current_levels, ctx, out, child_field));
}
out->field = ::arrow::field(group.name(), ::arrow::list(child_field->field),
group.is_optional(), FieldIdMetadata(group.field_id()));
out->level_info = current_levels;
// At this point current levels contains the def level for this list,
// we need to reset to the prior parent.
out->level_info.repeated_ancestor_def_level = repeated_ancestor_def_level;
return Status::OK();
}
Status GroupToSchemaField(const GroupNode& node, LevelInfo current_levels,
SchemaTreeContext* ctx, const SchemaField* parent,
SchemaField* out) {
if (node.logical_type()->is_list()) {
return ListToSchemaField(node, current_levels, ctx, parent, out);
} else if (node.logical_type()->is_map()) {
return MapToSchemaField(node, current_levels, ctx, parent, out);
}
std::shared_ptr<ArrowType> type;
if (node.is_repeated()) {
// Simple repeated struct
//
// repeated group $NAME {
// r/o TYPE[0] f0
// r/o TYPE[1] f1
// }
out->children.resize(1);
int16_t repeated_ancestor_def_level = current_levels.IncrementRepeated();
RETURN_NOT_OK(GroupToStruct(node, current_levels, ctx, out, &out->children[0]));
out->field = ::arrow::field(node.name(), ::arrow::list(out->children[0].field),
/*nullable=*/false, FieldIdMetadata(node.field_id()));
ctx->LinkParent(&out->children[0], out);
out->level_info = current_levels;
// At this point current_levels contains this list as the def level, we need to
// use the previous ancestor of this list.
out->level_info.repeated_ancestor_def_level = repeated_ancestor_def_level;
return Status::OK();
} else {
current_levels.Increment(node);
return GroupToStruct(node, current_levels, ctx, parent, out);
}
}
Status NodeToSchemaField(const Node& node, LevelInfo current_levels,
SchemaTreeContext* ctx, const SchemaField* parent,
SchemaField* out) {
// Workhorse function for converting a Parquet schema node to an Arrow
// type. Handles different conventions for nested data.
ctx->LinkParent(out, parent);
// Now, walk the schema and create a ColumnDescriptor for each leaf node
if (node.is_group()) {
// A nested field, but we don't know what kind yet
return GroupToSchemaField(static_cast<const GroupNode&>(node), current_levels, ctx,
parent, out);
} else {
// Either a normal flat primitive type, or a list type encoded with 1-level
// list encoding. Note that the 3-level encoding is the form recommended by
// the parquet specification, but technically we can have either
//
// required/optional $TYPE $FIELD_NAME
//
// or
//
// repeated $TYPE $FIELD_NAME
const auto& primitive_node = static_cast<const PrimitiveNode&>(node);
int column_index = ctx->schema->GetColumnIndex(primitive_node);
ASSIGN_OR_RAISE(std::shared_ptr<ArrowType> type,
GetTypeForNode(column_index, primitive_node, ctx));
if (node.is_repeated()) {
// One-level list encoding, e.g.
// a: repeated int32;
int16_t repeated_ancestor_def_level = current_levels.IncrementRepeated();
out->children.resize(1);
auto child_field = ::arrow::field(node.name(), type, /*nullable=*/false);
RETURN_NOT_OK(PopulateLeaf(column_index, child_field, current_levels, ctx, out,
&out->children[0]));
out->field = ::arrow::field(node.name(), ::arrow::list(child_field),
/*nullable=*/false, FieldIdMetadata(node.field_id()));
out->level_info = current_levels;
// At this point current_levels has consider this list the ancestor so restore
// the actual ancestor.
out->level_info.repeated_ancestor_def_level = repeated_ancestor_def_level;
return Status::OK();
} else {
current_levels.Increment(node);
// A normal (required/optional) primitive node
return PopulateLeaf(column_index,
::arrow::field(node.name(), type, node.is_optional(),
FieldIdMetadata(node.field_id())),
current_levels, ctx, parent, out);
}
}
}
// Get the original Arrow schema, as serialized in the Parquet metadata
Status GetOriginSchema(const std::shared_ptr<const KeyValueMetadata>& metadata,
std::shared_ptr<const KeyValueMetadata>* clean_metadata,
std::shared_ptr<::arrow::Schema>* out) {
if (metadata == nullptr) {
*out = nullptr;
*clean_metadata = nullptr;
return Status::OK();
}
static const std::string kArrowSchemaKey = "ARROW:schema";
int schema_index = metadata->FindKey(kArrowSchemaKey);
if (schema_index == -1) {
*out = nullptr;
*clean_metadata = metadata;
return Status::OK();
}
// The original Arrow schema was serialized using the store_schema option.
// We deserialize it here and use it to inform read options such as
// dictionary-encoded fields.
auto decoded = ::arrow::util::base64_decode(metadata->value(schema_index));
auto schema_buf = std::make_shared<Buffer>(decoded);
::arrow::ipc::DictionaryMemo dict_memo;
::arrow::io::BufferReader input(schema_buf);
ARROW_ASSIGN_OR_RAISE(*out, ::arrow::ipc::ReadSchema(&input, &dict_memo));
if (metadata->size() > 1) {
// Copy the metadata without the schema key
auto new_metadata = ::arrow::key_value_metadata({}, {});
new_metadata->reserve(metadata->size() - 1);
for (int64_t i = 0; i < metadata->size(); ++i) {
if (i == schema_index) continue;
new_metadata->Append(metadata->key(i), metadata->value(i));
}
*clean_metadata = new_metadata;
} else {
// No other keys, let metadata be null
*clean_metadata = nullptr;
}
return Status::OK();
}
// Restore original Arrow field information that was serialized as Parquet metadata
// but that is not necessarily present in the field reconstituted from Parquet data
// (for example, Parquet timestamp types doesn't carry timezone information).
Result<bool> ApplyOriginalMetadata(const Field& origin_field, SchemaField* inferred);
std::function<std::shared_ptr<::arrow::DataType>(FieldVector)> GetNestedFactory(
const ArrowType& origin_type, const ArrowType& inferred_type) {
switch (inferred_type.id()) {
case ::arrow::Type::STRUCT:
if (origin_type.id() == ::arrow::Type::STRUCT) {
return [](FieldVector fields) { return ::arrow::struct_(std::move(fields)); };
}
break;
case ::arrow::Type::LIST:
if (origin_type.id() == ::arrow::Type::LIST) {
return [](FieldVector fields) {
DCHECK_EQ(fields.size(), 1);
return ::arrow::list(std::move(fields[0]));
};
}
if (origin_type.id() == ::arrow::Type::LARGE_LIST) {
return [](FieldVector fields) {
DCHECK_EQ(fields.size(), 1);
return ::arrow::large_list(std::move(fields[0]));
};
}
if (origin_type.id() == ::arrow::Type::FIXED_SIZE_LIST) {
const auto list_size =
checked_cast<const ::arrow::FixedSizeListType&>(origin_type).list_size();
return [list_size](FieldVector fields) {
DCHECK_EQ(fields.size(), 1);
return ::arrow::fixed_size_list(std::move(fields[0]), list_size);
};
}
break;
default:
break;
}
return {};
}
Result<bool> ApplyOriginalStorageMetadata(const Field& origin_field,
SchemaField* inferred) {
bool modified = false;
auto& origin_type = origin_field.type();
auto& inferred_type = inferred->field->type();
const int num_children = inferred_type->num_fields();
if (num_children > 0 && origin_type->num_fields() == num_children) {
DCHECK_EQ(static_cast<int>(inferred->children.size()), num_children);
const auto factory = GetNestedFactory(*origin_type, *inferred_type);
if (factory) {
// The type may be modified (e.g. LargeList) while the children stay the same
modified |= origin_type->id() != inferred_type->id();
// Apply original metadata recursively to children
for (int i = 0; i < inferred_type->num_fields(); ++i) {
ARROW_ASSIGN_OR_RAISE(
const bool child_modified,
ApplyOriginalMetadata(*origin_type->field(i), &inferred->children[i]));
modified |= child_modified;
}
if (modified) {
// Recreate this field using the modified child fields
::arrow::FieldVector modified_children(inferred_type->num_fields());
for (int i = 0; i < inferred_type->num_fields(); ++i) {
modified_children[i] = inferred->children[i].field;
}
inferred->field =
inferred->field->WithType(factory(std::move(modified_children)));
}
}
}
if (origin_type->id() == ::arrow::Type::TIMESTAMP &&
inferred_type->id() == ::arrow::Type::TIMESTAMP) {
// Restore time zone, if any
const auto& ts_type = checked_cast<const ::arrow::TimestampType&>(*inferred_type);
const auto& ts_origin_type =
checked_cast<const ::arrow::TimestampType&>(*origin_type);
// If the data is tz-aware, then set the original time zone, since Parquet
// has no native storage for timezones
if (ts_type.timezone() == "UTC" && !ts_origin_type.timezone().empty()) {
if (ts_type.unit() == ts_origin_type.unit()) {
inferred->field = inferred->field->WithType(origin_type);
} else {
auto ts_type_new = ::arrow::timestamp(ts_type.unit(), ts_origin_type.timezone());
inferred->field = inferred->field->WithType(ts_type_new);
}
}
modified = true;
}
if (origin_type->id() == ::arrow::Type::DURATION &&
inferred_type->id() == ::arrow::Type::INT64) {
// Read back int64 arrays as duration.
inferred->field = inferred->field->WithType(origin_type);
modified = true;
}
if (origin_type->id() == ::arrow::Type::DICTIONARY &&
inferred_type->id() != ::arrow::Type::DICTIONARY &&
IsDictionaryReadSupported(*inferred_type)) {
// Direct dictionary reads are only supported for a couple primitive types,
// so no need to recurse on value types.
const auto& dict_origin_type =
checked_cast<const ::arrow::DictionaryType&>(*origin_type);
inferred->field = inferred->field->WithType(
::arrow::dictionary(::arrow::int32(), inferred_type, dict_origin_type.ordered()));
modified = true;
}
if ((origin_type->id() == ::arrow::Type::LARGE_BINARY &&
inferred_type->id() == ::arrow::Type::BINARY) ||
(origin_type->id() == ::arrow::Type::LARGE_STRING &&
inferred_type->id() == ::arrow::Type::STRING)) {
// Read back binary-like arrays with the intended offset width.
inferred->field = inferred->field->WithType(origin_type);
modified = true;
}
if (origin_type->id() == ::arrow::Type::DECIMAL256 &&
inferred_type->id() == ::arrow::Type::DECIMAL128) {
inferred->field = inferred->field->WithType(origin_type);
modified = true;
}
// Restore field metadata
std::shared_ptr<const KeyValueMetadata> field_metadata = origin_field.metadata();
if (field_metadata != nullptr) {
if (inferred->field->metadata()) {
// Prefer the metadata keys (like field_id) from the current metadata
field_metadata = field_metadata->Merge(*inferred->field->metadata());
}
inferred->field = inferred->field->WithMetadata(field_metadata);
modified = true;
}
return modified;
}
Result<bool> ApplyOriginalMetadata(const Field& origin_field, SchemaField* inferred) {
bool modified = false;
auto& origin_type = origin_field.type();
if (origin_type->id() == ::arrow::Type::EXTENSION) {
const auto& ex_type = checked_cast<const ::arrow::ExtensionType&>(*origin_type);
auto origin_storage_field = origin_field.WithType(ex_type.storage_type());
// Apply metadata recursively to storage type
RETURN_NOT_OK(ApplyOriginalStorageMetadata(*origin_storage_field, inferred));
// Restore extension type, if the storage type is the same as inferred
// from the Parquet type
if (ex_type.storage_type()->Equals(*inferred->field->type())) {
inferred->field = inferred->field->WithType(origin_type);
}
modified = true;