ClickHouse/src/Storages/MergeTree/MergeTreeReaderWide.cpp

288 lines
10 KiB
C++

#include <Storages/MergeTree/MergeTreeReaderWide.h>
#include <Columns/ColumnArray.h>
#include <DataTypes/DataTypeArray.h>
#include <DataTypes/NestedUtils.h>
#include <Interpreters/inplaceBlockConversions.h>
#include <Storages/MergeTree/IMergeTreeReader.h>
#include <Storages/MergeTree/MergeTreeDataPartWide.h>
#include <Common/escapeForFileName.h>
#include <Common/typeid_cast.h>
namespace DB
{
namespace
{
using OffsetColumns = std::map<std::string, ColumnPtr>;
constexpr auto DATA_FILE_EXTENSION = ".bin";
}
namespace ErrorCodes
{
extern const int MEMORY_LIMIT_EXCEEDED;
}
MergeTreeReaderWide::MergeTreeReaderWide(
DataPartWidePtr data_part_,
NamesAndTypesList columns_,
const StorageMetadataPtr & metadata_snapshot_,
UncompressedCache * uncompressed_cache_,
MarkCache * mark_cache_,
MarkRanges mark_ranges_,
MergeTreeReaderSettings settings_,
IMergeTreeDataPart::ValueSizeMap avg_value_size_hints_,
const ReadBufferFromFileBase::ProfileCallback & profile_callback_,
clockid_t clock_type_)
: IMergeTreeReader(
std::move(data_part_),
std::move(columns_),
metadata_snapshot_,
uncompressed_cache_,
std::move(mark_cache_),
std::move(mark_ranges_),
std::move(settings_),
std::move(avg_value_size_hints_))
{
try
{
disk = data_part->volume->getDisk();
for (const NameAndTypePair & column : columns)
{
auto column_from_part = getColumnFromPart(column);
addStreams(column_from_part, profile_callback_, clock_type_);
}
}
catch (...)
{
storage.reportBrokenPart(data_part->name);
throw;
}
}
size_t MergeTreeReaderWide::readRows(
size_t from_mark, size_t current_task_last_mark, bool continue_reading, size_t max_rows_to_read, Columns & res_columns)
{
size_t read_rows = 0;
try
{
size_t num_columns = columns.size();
checkNumberOfColumns(num_columns);
std::unordered_map<String, ISerialization::SubstreamsCache> caches;
std::unordered_set<std::string> prefetched_streams;
if (disk->isRemote() ? settings.read_settings.remote_fs_prefetch : settings.read_settings.local_fs_prefetch)
{
/// Request reading of data in advance,
/// so if reading can be asynchronous, it will also be performed in parallel for all columns.
auto name_and_type = columns.begin();
for (size_t pos = 0; pos < num_columns; ++pos, ++name_and_type)
{
auto column_from_part = getColumnFromPart(*name_and_type);
try
{
auto & cache = caches[column_from_part.getNameInStorage()];
prefetch(column_from_part, from_mark, continue_reading, current_task_last_mark, cache, prefetched_streams);
}
catch (Exception & e)
{
/// Better diagnostics.
e.addMessage("(while reading column " + column_from_part.name + ")");
throw;
}
}
}
auto name_and_type = columns.begin();
for (size_t pos = 0; pos < num_columns; ++pos, ++name_and_type)
{
auto column_from_part = getColumnFromPart(*name_and_type);
const auto & [name, type] = column_from_part;
/// The column is already present in the block so we will append the values to the end.
bool append = res_columns[pos] != nullptr;
if (!append)
res_columns[pos] = type->createColumn();
auto & column = res_columns[pos];
try
{
size_t column_size_before_reading = column->size();
auto & cache = caches[column_from_part.getNameInStorage()];
readData(
column_from_part, column, from_mark, continue_reading, current_task_last_mark,
max_rows_to_read, cache, /* was_prefetched =*/ !prefetched_streams.empty());
/// For elements of Nested, column_size_before_reading may be greater than column size
/// if offsets are not empty and were already read, but elements are empty.
if (!column->empty())
read_rows = std::max(read_rows, column->size() - column_size_before_reading);
}
catch (Exception & e)
{
/// Better diagnostics.
e.addMessage("(while reading column " + name + ")");
throw;
}
if (column->empty())
res_columns[pos] = nullptr;
}
/// NOTE: positions for all streams must be kept in sync.
/// In particular, even if for some streams there are no rows to be read,
/// you must ensure that no seeks are skipped and at this point they all point to to_mark.
}
catch (Exception & e)
{
if (e.code() != ErrorCodes::MEMORY_LIMIT_EXCEEDED)
storage.reportBrokenPart(data_part->name);
/// Better diagnostics.
e.addMessage("(while reading from part " + data_part->getFullPath() + " "
"from mark " + toString(from_mark) + " "
"with max_rows_to_read = " + toString(max_rows_to_read) + ")");
throw;
}
catch (...)
{
storage.reportBrokenPart(data_part->name);
throw;
}
return read_rows;
}
void MergeTreeReaderWide::addStreams(const NameAndTypePair & name_and_type,
const ReadBufferFromFileBase::ProfileCallback & profile_callback, clockid_t clock_type)
{
ISerialization::StreamCallback callback = [&] (const ISerialization::SubstreamPath & substream_path)
{
String stream_name = ISerialization::getFileNameForStream(name_and_type, substream_path);
if (streams.count(stream_name))
return;
bool data_file_exists = data_part->checksums.files.count(stream_name + DATA_FILE_EXTENSION);
/** If data file is missing then we will not try to open it.
* It is necessary since it allows to add new column to structure of the table without creating new files for old parts.
*/
if (!data_file_exists)
return;
streams.emplace(stream_name, std::make_unique<MergeTreeReaderStream>(
disk, data_part->getFullRelativePath() + stream_name, DATA_FILE_EXTENSION,
data_part->getMarksCount(), all_mark_ranges, settings, mark_cache,
uncompressed_cache, data_part->getFileSizeOrZero(stream_name + DATA_FILE_EXTENSION),
&data_part->index_granularity_info,
profile_callback, clock_type));
};
auto serialization = data_part->getSerializationForColumn(name_and_type);
serialization->enumerateStreams(callback);
serializations.emplace(name_and_type.name, std::move(serialization));
}
static ReadBuffer * getStream(
bool seek_to_start,
const ISerialization::SubstreamPath & substream_path,
MergeTreeReaderWide::FileStreams & streams,
const NameAndTypePair & name_and_type,
size_t from_mark, bool seek_to_mark,
size_t current_task_last_mark,
ISerialization::SubstreamsCache & cache)
{
/// If substream have already been read.
if (cache.count(ISerialization::getSubcolumnNameForStream(substream_path)))
return nullptr;
String stream_name = ISerialization::getFileNameForStream(name_and_type, substream_path);
auto it = streams.find(stream_name);
if (it == streams.end())
return nullptr;
MergeTreeReaderStream & stream = *it->second;
stream.adjustForRange(seek_to_start ? 0 : from_mark, current_task_last_mark);
if (seek_to_start)
stream.seekToStart();
else if (seek_to_mark)
stream.seekToMark(from_mark);
return stream.data_buffer;
}
void MergeTreeReaderWide::prefetch(
const NameAndTypePair & name_and_type,
size_t from_mark,
bool continue_reading,
size_t current_task_last_mark,
ISerialization::SubstreamsCache & cache,
std::unordered_set<std::string> & prefetched_streams)
{
const auto & name = name_and_type.name;
auto & serialization = serializations[name];
serialization->enumerateStreams([&](const ISerialization::SubstreamPath & substream_path)
{
String stream_name = ISerialization::getFileNameForStream(name_and_type, substream_path);
if (!prefetched_streams.count(stream_name))
{
bool seek_to_mark = !continue_reading;
if (ReadBuffer * buf = getStream(false, substream_path, streams, name_and_type, from_mark, seek_to_mark, current_task_last_mark, cache))
buf->prefetch();
prefetched_streams.insert(stream_name);
}
});
}
void MergeTreeReaderWide::readData(
const NameAndTypePair & name_and_type, ColumnPtr & column,
size_t from_mark, bool continue_reading, size_t current_task_last_mark,
size_t max_rows_to_read, ISerialization::SubstreamsCache & cache, bool was_prefetched)
{
double & avg_value_size_hint = avg_value_size_hints[name_and_type.name];
ISerialization::DeserializeBinaryBulkSettings deserialize_settings;
deserialize_settings.avg_value_size_hint = avg_value_size_hint;
const auto & name = name_and_type.name;
auto & serialization = serializations[name];
if (deserialize_binary_bulk_state_map.count(name) == 0)
{
deserialize_settings.getter = [&](const ISerialization::SubstreamPath & substream_path)
{
return getStream(/* seek_to_start = */true, substream_path, streams, name_and_type, from_mark, /* seek_to_mark = */false, current_task_last_mark, cache);
};
serialization->deserializeBinaryBulkStatePrefix(deserialize_settings, deserialize_binary_bulk_state_map[name]);
}
deserialize_settings.getter = [&](const ISerialization::SubstreamPath & substream_path)
{
bool seek_to_mark = !was_prefetched && !continue_reading;
return getStream(
/* seek_to_start = */false, substream_path, streams, name_and_type, from_mark,
seek_to_mark, current_task_last_mark, cache);
};
deserialize_settings.continuous_reading = continue_reading;
auto & deserialize_state = deserialize_binary_bulk_state_map[name];
serialization->deserializeBinaryBulkWithMultipleStreams(column, max_rows_to_read, deserialize_settings, deserialize_state, &cache);
IDataType::updateAvgValueSizeHint(*column, avg_value_size_hint);
}
}