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ClickHouse/src/Storages/MergeTree/MergeTreeRangeReader.cpp
Alexander Gololobov 48de02a7b8 Capitalized const name
2022-07-25 16:32:16 +02:00

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#include <Storages/MergeTree/IMergeTreeReader.h>
#include <Columns/FilterDescription.h>
#include <Columns/ColumnConst.h>
#include <Columns/ColumnsCommon.h>
#include <Common/TargetSpecific.h>
#include <IO/WriteBufferFromString.h>
#include <IO/Operators.h>
#include <base/range.h>
#include <Interpreters/castColumn.h>
#include <DataTypes/DataTypeNothing.h>
#ifdef __SSE2__
#include <emmintrin.h>
#endif
#if defined(__aarch64__) && defined(__ARM_NEON)
# include <arm_neon.h>
# ifdef HAS_RESERVED_IDENTIFIER
# pragma clang diagnostic ignored "-Wreserved-identifier"
# endif
#endif
namespace DB
{
namespace ErrorCodes
{
extern const int LOGICAL_ERROR;
extern const int BAD_ARGUMENTS;
}
static void filterColumns(Columns & columns, const IColumn::Filter & filter)
{
for (auto & column : columns)
{
if (column)
{
column = column->filter(filter, -1);
if (column->empty())
{
columns.clear();
return;
}
}
}
}
static void filterColumns(Columns & columns, const ColumnPtr & filter)
{
ConstantFilterDescription const_descr(*filter);
if (const_descr.always_true)
return;
if (const_descr.always_false)
{
for (auto & col : columns)
if (col)
col = col->cloneEmpty();
return;
}
FilterDescription descr(*filter);
filterColumns(columns, *descr.data);
}
size_t MergeTreeRangeReader::ReadResult::getLastMark(const MergeTreeRangeReader::ReadResult::RangesInfo & ranges)
{
size_t current_task_last_mark = 0;
for (const auto & mark_range : ranges)
current_task_last_mark = std::max(current_task_last_mark, mark_range.range.end);
return current_task_last_mark;
}
MergeTreeRangeReader::DelayedStream::DelayedStream(
size_t from_mark,
size_t current_task_last_mark_,
IMergeTreeReader * merge_tree_reader_)
: current_mark(from_mark), current_offset(0), num_delayed_rows(0)
, current_task_last_mark(current_task_last_mark_)
, merge_tree_reader(merge_tree_reader_)
, index_granularity(&(merge_tree_reader->data_part->index_granularity))
, continue_reading(false), is_finished(false)
{
}
size_t MergeTreeRangeReader::DelayedStream::position() const
{
size_t num_rows_before_current_mark = index_granularity->getMarkStartingRow(current_mark);
return num_rows_before_current_mark + current_offset + num_delayed_rows;
}
size_t MergeTreeRangeReader::DelayedStream::readRows(Columns & columns, size_t num_rows)
{
if (num_rows)
{
size_t rows_read = merge_tree_reader->readRows(
current_mark, current_task_last_mark, continue_reading, num_rows, columns);
continue_reading = true;
/// Zero rows_read maybe either because reading has finished
/// or because there is no columns we can read in current part (for example, all columns are default).
/// In the last case we can't finish reading, but it's also ok for the first case
/// because we can finish reading by calculation the number of pending rows.
if (0 < rows_read && rows_read < num_rows)
is_finished = true;
return rows_read;
}
return 0;
}
size_t MergeTreeRangeReader::DelayedStream::read(Columns & columns, size_t from_mark, size_t offset, size_t num_rows)
{
size_t num_rows_before_from_mark = index_granularity->getMarkStartingRow(from_mark);
/// We already stand accurately in required position,
/// so because stream is lazy, we don't read anything
/// and only increment amount delayed_rows
if (position() == num_rows_before_from_mark + offset)
{
num_delayed_rows += num_rows;
return 0;
}
else
{
size_t read_rows = finalize(columns);
continue_reading = false;
current_mark = from_mark;
current_offset = offset;
num_delayed_rows = num_rows;
return read_rows;
}
}
size_t MergeTreeRangeReader::DelayedStream::finalize(Columns & columns)
{
/// We need to skip some rows before reading
if (current_offset && !continue_reading)
{
for (size_t mark_num : collections::range(current_mark, index_granularity->getMarksCount()))
{
size_t mark_index_granularity = index_granularity->getMarkRows(mark_num);
if (current_offset >= mark_index_granularity)
{
current_offset -= mark_index_granularity;
current_mark++;
}
else
break;
}
/// Skip some rows from begin of granule.
/// We don't know size of rows in compressed granule,
/// so have to read them and throw out.
if (current_offset)
{
Columns tmp_columns;
tmp_columns.resize(columns.size());
readRows(tmp_columns, current_offset);
}
}
size_t rows_to_read = num_delayed_rows;
current_offset += num_delayed_rows;
num_delayed_rows = 0;
return readRows(columns, rows_to_read);
}
MergeTreeRangeReader::Stream::Stream(
size_t from_mark, size_t to_mark, size_t current_task_last_mark, IMergeTreeReader * merge_tree_reader_)
: current_mark(from_mark), offset_after_current_mark(0)
, last_mark(to_mark)
, merge_tree_reader(merge_tree_reader_)
, index_granularity(&(merge_tree_reader->data_part->index_granularity))
, current_mark_index_granularity(index_granularity->getMarkRows(from_mark))
, stream(from_mark, current_task_last_mark, merge_tree_reader)
{
size_t marks_count = index_granularity->getMarksCount();
if (from_mark >= marks_count)
throw Exception("Trying create stream to read from mark №"+ toString(current_mark) + " but total marks count is "
+ toString(marks_count), ErrorCodes::LOGICAL_ERROR);
if (last_mark > marks_count)
throw Exception("Trying create stream to read to mark №"+ toString(current_mark) + " but total marks count is "
+ toString(marks_count), ErrorCodes::LOGICAL_ERROR);
}
void MergeTreeRangeReader::Stream::checkNotFinished() const
{
if (isFinished())
throw Exception("Cannot read out of marks range.", ErrorCodes::BAD_ARGUMENTS);
}
void MergeTreeRangeReader::Stream::checkEnoughSpaceInCurrentGranule(size_t num_rows) const
{
if (num_rows + offset_after_current_mark > current_mark_index_granularity)
throw Exception("Cannot read from granule more than index_granularity.", ErrorCodes::LOGICAL_ERROR);
}
size_t MergeTreeRangeReader::Stream::readRows(Columns & columns, size_t num_rows)
{
size_t rows_read = stream.read(columns, current_mark, offset_after_current_mark, num_rows);
if (stream.isFinished())
finish();
return rows_read;
}
void MergeTreeRangeReader::Stream::toNextMark()
{
++current_mark;
size_t total_marks_count = index_granularity->getMarksCount();
if (current_mark < total_marks_count)
current_mark_index_granularity = index_granularity->getMarkRows(current_mark);
else if (current_mark == total_marks_count)
current_mark_index_granularity = 0; /// HACK?
else
throw Exception("Trying to read from mark " + toString(current_mark) + ", but total marks count " + toString(total_marks_count), ErrorCodes::LOGICAL_ERROR);
offset_after_current_mark = 0;
}
size_t MergeTreeRangeReader::Stream::read(Columns & columns, size_t num_rows, bool skip_remaining_rows_in_current_granule)
{
checkEnoughSpaceInCurrentGranule(num_rows);
if (num_rows)
{
checkNotFinished();
size_t read_rows = readRows(columns, num_rows);
offset_after_current_mark += num_rows;
/// Start new granule; skipped_rows_after_offset is already zero.
if (offset_after_current_mark == current_mark_index_granularity || skip_remaining_rows_in_current_granule)
toNextMark();
return read_rows;
}
else
{
/// Nothing to read.
if (skip_remaining_rows_in_current_granule)
{
/// Skip the rest of the rows in granule and start new one.
checkNotFinished();
toNextMark();
}
return 0;
}
}
void MergeTreeRangeReader::Stream::skip(size_t num_rows)
{
if (num_rows)
{
checkNotFinished();
checkEnoughSpaceInCurrentGranule(num_rows);
offset_after_current_mark += num_rows;
if (offset_after_current_mark == current_mark_index_granularity)
{
/// Start new granule; skipped_rows_after_offset is already zero.
toNextMark();
}
}
}
size_t MergeTreeRangeReader::Stream::finalize(Columns & columns)
{
size_t read_rows = stream.finalize(columns);
if (stream.isFinished())
finish();
return read_rows;
}
void MergeTreeRangeReader::ReadResult::addGranule(size_t num_rows_)
{
rows_per_granule.push_back(num_rows_);
total_rows_per_granule += num_rows_;
}
void MergeTreeRangeReader::ReadResult::adjustLastGranule()
{
size_t num_rows_to_subtract = total_rows_per_granule - num_read_rows;
if (rows_per_granule.empty())
throw Exception("Can't adjust last granule because no granules were added", ErrorCodes::LOGICAL_ERROR);
if (num_rows_to_subtract > rows_per_granule.back())
throw Exception(ErrorCodes::LOGICAL_ERROR,
"Can't adjust last granule because it has {} rows, but try to subtract {} rows.",
toString(rows_per_granule.back()), toString(num_rows_to_subtract));
rows_per_granule.back() -= num_rows_to_subtract;
total_rows_per_granule -= num_rows_to_subtract;
}
void MergeTreeRangeReader::ReadResult::clear()
{
/// Need to save information about the number of granules.
num_rows_to_skip_in_last_granule += rows_per_granule.back();
rows_per_granule.assign(rows_per_granule.size(), 0);
total_rows_per_granule = 0;
filter_holder = nullptr;
filter = nullptr;
}
void MergeTreeRangeReader::ReadResult::shrink(Columns & old_columns)
{
for (auto & column : old_columns)
{
if (!column)
continue;
if (const auto * column_const = typeid_cast<const ColumnConst *>(column.get()))
{
column = column_const->cloneResized(total_rows_per_granule);
continue;
}
auto new_column = column->cloneEmpty();
new_column->reserve(total_rows_per_granule);
for (size_t j = 0, pos = 0; j < rows_per_granule_original.size(); pos += rows_per_granule_original[j++])
{
if (rows_per_granule[j])
new_column->insertRangeFrom(*column, pos, rows_per_granule[j]);
}
column = std::move(new_column);
}
}
void MergeTreeRangeReader::ReadResult::setFilterConstTrue()
{
clearFilter();
filter_holder = DataTypeUInt8().createColumnConst(num_rows, 1u);
}
void MergeTreeRangeReader::ReadResult::setFilterConstFalse()
{
clearFilter();
columns.clear();
num_rows = 0;
}
void MergeTreeRangeReader::ReadResult::optimize(bool can_read_incomplete_granules, bool allow_filter_columns)
{
if (total_rows_per_granule == 0 || filter == nullptr)
return;
NumRows zero_tails;
auto total_zero_rows_in_tails = countZeroTails(filter->getData(), zero_tails, can_read_incomplete_granules);
if (total_zero_rows_in_tails == filter->size())
{
clear();
return;
}
else if (total_zero_rows_in_tails == 0 && countBytesInResultFilter(filter->getData()) == filter->size())
{
setFilterConstTrue();
return;
}
/// Just a guess. If only a few rows may be skipped, it's better not to skip at all.
else if (2 * total_zero_rows_in_tails > filter->size())
{
for (auto i : collections::range(0, rows_per_granule.size()))
{
rows_per_granule_original.push_back(rows_per_granule[i]);
rows_per_granule[i] -= zero_tails[i];
}
num_rows_to_skip_in_last_granule += rows_per_granule_original.back() - rows_per_granule.back();
filter_original = filter;
filter_holder_original = std::move(filter_holder);
/// Check if const 1 after shrink
if (allow_filter_columns && countBytesInResultFilter(filter->getData()) + total_zero_rows_in_tails == total_rows_per_granule)
{
total_rows_per_granule = total_rows_per_granule - total_zero_rows_in_tails;
num_rows = total_rows_per_granule;
setFilterConstTrue();
shrink(columns); /// shrink acts as filtering in such case
}
else
{
auto new_filter = ColumnUInt8::create(filter->size() - total_zero_rows_in_tails);
IColumn::Filter & new_data = new_filter->getData();
collapseZeroTails(filter->getData(), new_data);
total_rows_per_granule = new_filter->size();
num_rows = total_rows_per_granule;
filter = new_filter.get();
filter_holder = std::move(new_filter);
}
need_filter = true;
}
/// Another guess, if it's worth filtering at PREWHERE
else if (countBytesInResultFilter(filter->getData()) < 0.6 * filter->size())
need_filter = true;
}
size_t MergeTreeRangeReader::ReadResult::countZeroTails(const IColumn::Filter & filter_vec, NumRows & zero_tails, bool can_read_incomplete_granules) const
{
zero_tails.resize(0);
zero_tails.reserve(rows_per_granule.size());
const auto * filter_data = filter_vec.data();
size_t total_zero_rows_in_tails = 0;
for (auto rows_to_read : rows_per_granule)
{
/// Count the number of zeros at the end of filter for rows were read from current granule.
size_t zero_tail = numZerosInTail(filter_data, filter_data + rows_to_read);
if (!can_read_incomplete_granules && zero_tail != rows_to_read)
zero_tail = 0;
zero_tails.push_back(zero_tail);
total_zero_rows_in_tails += zero_tails.back();
filter_data += rows_to_read;
}
return total_zero_rows_in_tails;
}
void MergeTreeRangeReader::ReadResult::collapseZeroTails(const IColumn::Filter & filter_vec, IColumn::Filter & new_filter_vec)
{
const auto * filter_data = filter_vec.data();
auto * new_filter_data = new_filter_vec.data();
for (auto i : collections::range(0, rows_per_granule.size()))
{
memcpySmallAllowReadWriteOverflow15(new_filter_data, filter_data, rows_per_granule[i]);
filter_data += rows_per_granule_original[i];
new_filter_data += rows_per_granule[i];
}
new_filter_vec.resize(new_filter_data - new_filter_vec.data());
}
DECLARE_AVX512BW_SPECIFIC_CODE(
size_t numZerosInTail(const UInt8 * begin, const UInt8 * end)
{
size_t count = 0;
const __m512i zero64 = _mm512_setzero_epi32();
while (end - begin >= 64)
{
end -= 64;
const auto * pos = end;
UInt64 val = static_cast<UInt64>(_mm512_cmp_epi8_mask(
_mm512_loadu_si512(reinterpret_cast<const __m512i *>(pos)),
zero64,
_MM_CMPINT_EQ));
val = ~val;
if (val == 0)
count += 64;
else
{
count += __builtin_clzll(val);
return count;
}
}
while (end > begin && *(--end) == 0)
{
++count;
}
return count;
}
) /// DECLARE_AVX512BW_SPECIFIC_CODE
DECLARE_AVX2_SPECIFIC_CODE(
size_t numZerosInTail(const UInt8 * begin, const UInt8 * end)
{
size_t count = 0;
const __m256i zero32 = _mm256_setzero_si256();
while (end - begin >= 64)
{
end -= 64;
const auto * pos = end;
UInt64 val =
(static_cast<UInt64>(_mm256_movemask_epi8(_mm256_cmpeq_epi8(
_mm256_loadu_si256(reinterpret_cast<const __m256i *>(pos)),
zero32))) & 0xffffffffu)
| (static_cast<UInt64>(_mm256_movemask_epi8(_mm256_cmpeq_epi8(
_mm256_loadu_si256(reinterpret_cast<const __m256i *>(pos + 32)),
zero32))) << 32u);
val = ~val;
if (val == 0)
count += 64;
else
{
count += __builtin_clzll(val);
return count;
}
}
while (end > begin && *(--end) == 0)
{
++count;
}
return count;
}
) /// DECLARE_AVX2_SPECIFIC_CODE
size_t MergeTreeRangeReader::ReadResult::numZerosInTail(const UInt8 * begin, const UInt8 * end)
{
#if USE_MULTITARGET_CODE
/// check if cpu support avx512 dynamically, haveAVX512BW contains check of haveAVX512F
if (isArchSupported(TargetArch::AVX512BW))
return TargetSpecific::AVX512BW::numZerosInTail(begin, end);
else if (isArchSupported(TargetArch::AVX2))
return TargetSpecific::AVX2::numZerosInTail(begin, end);
#endif
size_t count = 0;
#if defined(__SSE2__) && defined(__POPCNT__)
const __m128i zero16 = _mm_setzero_si128();
while (end - begin >= 64)
{
end -= 64;
const auto * pos = end;
UInt64 val =
static_cast<UInt64>(_mm_movemask_epi8(_mm_cmpeq_epi8(
_mm_loadu_si128(reinterpret_cast<const __m128i *>(pos)),
zero16)))
| (static_cast<UInt64>(_mm_movemask_epi8(_mm_cmpeq_epi8(
_mm_loadu_si128(reinterpret_cast<const __m128i *>(pos + 16)),
zero16))) << 16u)
| (static_cast<UInt64>(_mm_movemask_epi8(_mm_cmpeq_epi8(
_mm_loadu_si128(reinterpret_cast<const __m128i *>(pos + 32)),
zero16))) << 32u)
| (static_cast<UInt64>(_mm_movemask_epi8(_mm_cmpeq_epi8(
_mm_loadu_si128(reinterpret_cast<const __m128i *>(pos + 48)),
zero16))) << 48u);
val = ~val;
if (val == 0)
count += 64;
else
{
count += __builtin_clzll(val);
return count;
}
}
#elif defined(__aarch64__) && defined(__ARM_NEON)
const uint8x16_t bitmask = {0x01, 0x02, 0x4, 0x8, 0x10, 0x20, 0x40, 0x80, 0x01, 0x02, 0x4, 0x8, 0x10, 0x20, 0x40, 0x80};
while (end - begin >= 64)
{
end -= 64;
const auto * src = reinterpret_cast<const unsigned char *>(end);
const uint8x16_t p0 = vceqzq_u8(vld1q_u8(src));
const uint8x16_t p1 = vceqzq_u8(vld1q_u8(src + 16));
const uint8x16_t p2 = vceqzq_u8(vld1q_u8(src + 32));
const uint8x16_t p3 = vceqzq_u8(vld1q_u8(src + 48));
uint8x16_t t0 = vandq_u8(p0, bitmask);
uint8x16_t t1 = vandq_u8(p1, bitmask);
uint8x16_t t2 = vandq_u8(p2, bitmask);
uint8x16_t t3 = vandq_u8(p3, bitmask);
uint8x16_t sum0 = vpaddq_u8(t0, t1);
uint8x16_t sum1 = vpaddq_u8(t2, t3);
sum0 = vpaddq_u8(sum0, sum1);
sum0 = vpaddq_u8(sum0, sum0);
UInt64 val = vgetq_lane_u64(vreinterpretq_u64_u8(sum0), 0);
val = ~val;
if (val == 0)
count += 64;
else
{
count += __builtin_clzll(val);
return count;
}
}
#endif
while (end > begin && *(--end) == 0)
{
++count;
}
return count;
}
/// Filter size must match total_rows_per_granule
void MergeTreeRangeReader::ReadResult::setFilter(const ColumnPtr & new_filter)
{
if (!new_filter && filter)
throw Exception("Can't replace existing filter with empty.", ErrorCodes::LOGICAL_ERROR);
if (filter)
{
size_t new_size = new_filter->size();
if (new_size != total_rows_per_granule)
throw Exception("Can't set filter because it's size is " + toString(new_size) + " but "
+ toString(total_rows_per_granule) + " rows was read.", ErrorCodes::LOGICAL_ERROR);
}
ConstantFilterDescription const_description(*new_filter);
if (const_description.always_true)
{
setFilterConstTrue();
}
else if (const_description.always_false)
{
clear();
}
else
{
FilterDescription filter_description(*new_filter);
filter_holder = filter_description.data_holder ? filter_description.data_holder : new_filter;
filter = typeid_cast<const ColumnUInt8 *>(filter_holder.get());
if (!filter)
throw Exception("setFilter function expected ColumnUInt8.", ErrorCodes::LOGICAL_ERROR);
}
}
size_t MergeTreeRangeReader::ReadResult::countBytesInResultFilter(const IColumn::Filter & filter_)
{
auto it = filter_bytes_map.find(&filter_);
if (it == filter_bytes_map.end())
{
auto bytes = countBytesInFilter(filter_);
filter_bytes_map[&filter_] = bytes;
return bytes;
}
else
return it->second;
}
MergeTreeRangeReader::MergeTreeRangeReader(
IMergeTreeReader * merge_tree_reader_,
MergeTreeRangeReader * prev_reader_,
const PrewhereExprStep * prewhere_info_,
bool last_reader_in_chain_,
const Names & non_const_virtual_column_names_)
: merge_tree_reader(merge_tree_reader_)
, index_granularity(&(merge_tree_reader->data_part->index_granularity))
, prev_reader(prev_reader_)
, prewhere_info(prewhere_info_)
, last_reader_in_chain(last_reader_in_chain_)
, is_initialized(true)
{
if (prev_reader)
sample_block = prev_reader->getSampleBlock();
for (const auto & name_and_type : merge_tree_reader->getColumns())
sample_block.insert({name_and_type.type->createColumn(), name_and_type.type, name_and_type.name});
for (const auto & column_name : non_const_virtual_column_names_)
{
if (sample_block.has(column_name))
continue;
non_const_virtual_column_names.push_back(column_name);
if (column_name == "_part_offset")
sample_block.insert(ColumnWithTypeAndName(ColumnUInt64::create(), std::make_shared<DataTypeUInt64>(), column_name));
}
if (prewhere_info)
{
const auto & step = *prewhere_info;
if (step.actions)
step.actions->execute(sample_block, true);
if (step.remove_column)
sample_block.erase(step.column_name);
}
}
bool MergeTreeRangeReader::isReadingFinished() const
{
return prev_reader ? prev_reader->isReadingFinished() : stream.isFinished();
}
size_t MergeTreeRangeReader::numReadRowsInCurrentGranule() const
{
return prev_reader ? prev_reader->numReadRowsInCurrentGranule() : stream.numReadRowsInCurrentGranule();
}
size_t MergeTreeRangeReader::numPendingRowsInCurrentGranule() const
{
if (prev_reader)
return prev_reader->numPendingRowsInCurrentGranule();
auto pending_rows = stream.numPendingRowsInCurrentGranule();
if (pending_rows)
return pending_rows;
return numRowsInCurrentGranule();
}
size_t MergeTreeRangeReader::numRowsInCurrentGranule() const
{
/// If pending_rows is zero, than stream is not initialized.
if (stream.current_mark_index_granularity)
return stream.current_mark_index_granularity;
/// We haven't read anything, return first
size_t first_mark = merge_tree_reader->getFirstMarkToRead();
return index_granularity->getMarkRows(first_mark);
}
size_t MergeTreeRangeReader::currentMark() const
{
return stream.currentMark();
}
size_t MergeTreeRangeReader::Stream::numPendingRows() const
{
size_t rows_between_marks = index_granularity->getRowsCountInRange(current_mark, last_mark);
return rows_between_marks - offset_after_current_mark;
}
UInt64 MergeTreeRangeReader::Stream::currentPartOffset() const
{
return index_granularity->getMarkStartingRow(current_mark) + offset_after_current_mark;
}
UInt64 MergeTreeRangeReader::Stream::lastPartOffset() const
{
return index_granularity->getMarkStartingRow(last_mark);
}
size_t MergeTreeRangeReader::Stream::ceilRowsToCompleteGranules(size_t rows_num) const
{
/// FIXME suboptimal
size_t result = 0;
size_t from_mark = current_mark;
while (result < rows_num && from_mark < last_mark)
result += index_granularity->getMarkRows(from_mark++);
return result;
}
bool MergeTreeRangeReader::isCurrentRangeFinished() const
{
return prev_reader ? prev_reader->isCurrentRangeFinished() : stream.isFinished();
}
MergeTreeRangeReader::ReadResult MergeTreeRangeReader::read(size_t max_rows, MarkRanges & ranges)
{
if (max_rows == 0)
throw Exception("Expected at least 1 row to read, got 0.", ErrorCodes::LOGICAL_ERROR);
ReadResult read_result;
if (prev_reader)
{
read_result = prev_reader->read(max_rows, ranges);
size_t num_read_rows;
Columns columns = continueReadingChain(read_result, num_read_rows);
/// Nothing to do. Return empty result.
if (read_result.num_rows == 0)
return read_result;
bool has_columns = false;
size_t total_bytes = 0;
for (auto & column : columns)
{
if (column)
{
total_bytes += column->byteSize();
has_columns = true;
}
}
read_result.addNumBytesRead(total_bytes);
bool should_evaluate_missing_defaults = false;
if (has_columns)
{
/// num_read_rows >= read_result.num_rows
/// We must filter block before adding columns to read_result.block
/// Fill missing columns before filtering because some arrays from Nested may have empty data.
merge_tree_reader->fillMissingColumns(columns, should_evaluate_missing_defaults, num_read_rows);
if (read_result.getFilter())
filterColumns(columns, read_result.getFilter()->getData());
}
else
{
size_t num_rows = read_result.num_rows;
/// If block is empty, we still may need to add missing columns.
/// In that case use number of rows in result block and don't filter block.
if (num_rows)
merge_tree_reader->fillMissingColumns(columns, should_evaluate_missing_defaults, num_rows);
}
if (!columns.empty())
{
/// If some columns absent in part, then evaluate default values
if (should_evaluate_missing_defaults)
{
auto block = prev_reader->sample_block.cloneWithColumns(read_result.columns);
auto block_before_prewhere = read_result.block_before_prewhere;
for (const auto & column : block)
{
if (block_before_prewhere.has(column.name))
block_before_prewhere.erase(column.name);
}
if (block_before_prewhere)
{
if (read_result.need_filter)
{
auto old_columns = block_before_prewhere.getColumns();
filterColumns(old_columns, read_result.getFilterOriginal()->getData());
block_before_prewhere.setColumns(old_columns);
}
for (auto & column : block_before_prewhere)
block.insert(std::move(column));
}
merge_tree_reader->evaluateMissingDefaults(block, columns);
}
/// If columns not empty, then apply on-fly alter conversions if any required
merge_tree_reader->performRequiredConversions(columns);
}
read_result.columns.reserve(read_result.columns.size() + columns.size());
for (auto & column : columns)
read_result.columns.emplace_back(std::move(column));
}
else
{
read_result = startReadingChain(max_rows, ranges);
read_result.num_rows = read_result.numReadRows();
if (read_result.num_rows)
{
/// Physical columns go first and then some virtual columns follow
/// TODO: is there a better way to account for virtual columns that were filled by previous readers?
size_t physical_columns_count = read_result.columns.size() - read_result.extra_columns_filled.size();
Columns physical_columns(read_result.columns.begin(), read_result.columns.begin() + physical_columns_count);
bool should_evaluate_missing_defaults;
merge_tree_reader->fillMissingColumns(physical_columns, should_evaluate_missing_defaults,
read_result.num_rows);
/// If some columns absent in part, then evaluate default values
if (should_evaluate_missing_defaults)
merge_tree_reader->evaluateMissingDefaults({}, physical_columns);
/// If result not empty, then apply on-fly alter conversions if any required
merge_tree_reader->performRequiredConversions(physical_columns);
for (size_t i = 0; i < physical_columns.size(); ++i)
read_result.columns[i] = std::move(physical_columns[i]);
}
else
read_result.columns.clear();
size_t total_bytes = 0;
for (auto & column : read_result.columns)
total_bytes += column->byteSize();
read_result.addNumBytesRead(total_bytes);
}
if (read_result.num_rows == 0)
return read_result;
executePrewhereActionsAndFilterColumns(read_result);
return read_result;
}
MergeTreeRangeReader::ReadResult MergeTreeRangeReader::startReadingChain(size_t max_rows, MarkRanges & ranges)
{
ReadResult result;
result.columns.resize(merge_tree_reader->getColumns().size());
size_t current_task_last_mark = getLastMark(ranges);
/// The stream could be unfinished by the previous read request because of max_rows limit.
/// In this case it will have some rows from the previously started range. We need to save their begin and
/// end offsets to properly fill _part_offset column.
UInt64 leading_begin_part_offset = 0;
UInt64 leading_end_part_offset = 0;
if (!stream.isFinished())
{
leading_begin_part_offset = stream.currentPartOffset();
leading_end_part_offset = stream.lastPartOffset();
}
/// Stream is lazy. result.num_added_rows is the number of rows added to block which is not equal to
/// result.num_rows_read until call to stream.finalize(). Also result.num_added_rows may be less than
/// result.num_rows_read if the last granule in range also the last in part (so we have to adjust last granule).
{
size_t space_left = max_rows;
while (space_left && (!stream.isFinished() || !ranges.empty()))
{
if (stream.isFinished())
{
result.addRows(stream.finalize(result.columns));
stream = Stream(ranges.front().begin, ranges.front().end, current_task_last_mark, merge_tree_reader);
result.addRange(ranges.front());
ranges.pop_front();
}
size_t current_space = space_left;
/// If reader can't read part of granule, we have to increase number of reading rows
/// to read complete granules and exceed max_rows a bit.
if (!merge_tree_reader->canReadIncompleteGranules())
current_space = stream.ceilRowsToCompleteGranules(space_left);
auto rows_to_read = std::min(current_space, stream.numPendingRowsInCurrentGranule());
bool last = rows_to_read == space_left;
result.addRows(stream.read(result.columns, rows_to_read, !last));
result.addGranule(rows_to_read);
space_left = (rows_to_read > space_left ? 0 : space_left - rows_to_read);
}
}
result.addRows(stream.finalize(result.columns));
/// Last granule may be incomplete.
result.adjustLastGranule();
for (const auto & column_name : non_const_virtual_column_names)
{
if (column_name == "_part_offset")
fillPartOffsetColumn(result, leading_begin_part_offset, leading_end_part_offset);
}
return result;
}
void MergeTreeRangeReader::fillPartOffsetColumn(ReadResult & result, UInt64 leading_begin_part_offset, UInt64 leading_end_part_offset)
{
size_t num_rows = result.numReadRows();
auto column = ColumnUInt64::create(num_rows);
ColumnUInt64::Container & vec = column->getData();
UInt64 * pos = vec.data();
UInt64 * end = &vec[num_rows];
while (pos < end && leading_begin_part_offset < leading_end_part_offset)
*pos++ = leading_begin_part_offset++;
const auto start_ranges = result.startedRanges();
for (const auto & start_range : start_ranges)
{
UInt64 start_part_offset = index_granularity->getMarkStartingRow(start_range.range.begin);
UInt64 end_part_offset = index_granularity->getMarkStartingRow(start_range.range.end);
while (pos < end && start_part_offset < end_part_offset)
*pos++ = start_part_offset++;
}
result.columns.emplace_back(std::move(column));
result.extra_columns_filled.push_back("_part_offset");
}
Columns MergeTreeRangeReader::continueReadingChain(const ReadResult & result, size_t & num_rows)
{
Columns columns;
num_rows = 0;
/// No columns need to be read at this step? (only more filtering)
if (merge_tree_reader->getColumns().empty())
return columns;
if (result.rowsPerGranule().empty())
{
/// If zero rows were read on prev step, than there is no more rows to read.
/// Last granule may have less rows than index_granularity, so finish reading manually.
stream.finish();
return columns;
}
columns.resize(merge_tree_reader->numColumnsInResult());
const auto & rows_per_granule = result.rowsPerGranule();
const auto & started_ranges = result.startedRanges();
size_t current_task_last_mark = ReadResult::getLastMark(started_ranges);
size_t next_range_to_start = 0;
auto size = rows_per_granule.size();
for (auto i : collections::range(0, size))
{
if (next_range_to_start < started_ranges.size()
&& i == started_ranges[next_range_to_start].num_granules_read_before_start)
{
num_rows += stream.finalize(columns);
const auto & range = started_ranges[next_range_to_start].range;
++next_range_to_start;
stream = Stream(range.begin, range.end, current_task_last_mark, merge_tree_reader);
}
bool last = i + 1 == size;
num_rows += stream.read(columns, rows_per_granule[i], !last);
}
stream.skip(result.numRowsToSkipInLastGranule());
num_rows += stream.finalize(columns);
/// added_rows may be zero if all columns were read in prewhere and it's ok.
if (num_rows && num_rows != result.totalRowsPerGranule())
throw Exception("RangeReader read " + toString(num_rows) + " rows, but "
+ toString(result.totalRowsPerGranule()) + " expected.", ErrorCodes::LOGICAL_ERROR);
return columns;
}
static void checkCombinedFiltersSize(size_t bytes_in_first_filter, size_t second_filter_size)
{
if (bytes_in_first_filter != second_filter_size)
throw Exception(ErrorCodes::LOGICAL_ERROR,
"Cannot combine filters because number of bytes in a first filter ({}) "
"does not match second filter size ({})", bytes_in_first_filter, second_filter_size);
}
/// Second filter size must be equal to number of 1s in the first filter.
/// The result size is equal to first filter size.
static ColumnPtr combineFilters(ColumnPtr first, ColumnPtr second)
{
ConstantFilterDescription first_const_descr(*first);
if (first_const_descr.always_true)
{
checkCombinedFiltersSize(first->size(), second->size());
return second;
}
if (first_const_descr.always_false)
{
checkCombinedFiltersSize(0, second->size());
return first;
}
FilterDescription first_descr(*first);
size_t bytes_in_first_filter = countBytesInFilter(*first_descr.data);
checkCombinedFiltersSize(bytes_in_first_filter, second->size());
ConstantFilterDescription second_const_descr(*second);
if (second_const_descr.always_true)
return first;
if (second_const_descr.always_false)
return second->cloneResized(first->size());
FilterDescription second_descr(*second);
MutableColumnPtr mut_first;
if (first_descr.data_holder)
mut_first = IColumn::mutate(std::move(first_descr.data_holder));
else
mut_first = IColumn::mutate(std::move(first));
auto & first_data = typeid_cast<ColumnUInt8 *>(mut_first.get())->getData();
const auto * second_data = second_descr.data->data();
for (auto & val : first_data)
{
if (val)
{
val = *second_data;
++second_data;
}
}
return mut_first;
}
void MergeTreeRangeReader::executePrewhereActionsAndFilterColumns(ReadResult & result)
{
if (!prewhere_info)
return;
const auto & header = merge_tree_reader->getColumns();
size_t num_columns = header.size();
/// Check that we have columns from previous steps and newly read required columns
if (result.columns.size() < num_columns + result.extra_columns_filled.size())
throw Exception(ErrorCodes::LOGICAL_ERROR,
"Invalid number of columns passed to MergeTreeRangeReader. Expected {}, got {}",
num_columns, result.columns.size());
/// This filter has the size of total_rows_per granule. It is applied after reading contiguous chunks from
/// the start of each granule.
ColumnPtr combined_filter;
/// Filter computed at the current step. Its size is equal to num_rows which is <= total_rows_per_granule
ColumnPtr current_step_filter;
size_t prewhere_column_pos;
{
/// Restore block from columns list.
Block block;
size_t pos = 0;
if (prev_reader)
{
for (const auto & col : prev_reader->getSampleBlock())
{
block.insert({result.columns[pos], col.type, col.name});
++pos;
}
}
for (auto name_and_type = header.begin(); name_and_type != header.end() && pos < result.columns.size(); ++pos, ++name_and_type)
block.insert({result.columns[pos], name_and_type->type, name_and_type->name});
for (const auto & column_name : non_const_virtual_column_names)
{
if (block.has(column_name))
continue;
if (column_name == "_part_offset")
{
if (pos >= result.columns.size())
throw Exception(ErrorCodes::LOGICAL_ERROR,
"Invalid number of columns passed to MergeTreeRangeReader. Expected {}, got {}",
num_columns, result.columns.size());
block.insert({result.columns[pos], std::make_shared<DataTypeUInt64>(), column_name});
}
else if (column_name == LightweightDeleteDescription::FILTER_COLUMN.name)
{
/// Do nothing, it will be added later
}
else
throw Exception("Unexpected non-const virtual column: " + column_name, ErrorCodes::LOGICAL_ERROR);
++pos;
}
/// Columns might be projected out. We need to store them here so that default columns can be evaluated later.
result.block_before_prewhere = block;
if (prewhere_info->actions)
prewhere_info->actions->execute(block);
prewhere_column_pos = block.getPositionByName(prewhere_info->column_name);
result.columns.clear();
result.columns.reserve(block.columns());
for (auto & col : block)
result.columns.emplace_back(std::move(col.column));
current_step_filter.swap(result.columns[prewhere_column_pos]);
combined_filter = current_step_filter;
}
if (result.getFilter())
{
ColumnPtr prev_filter = result.getFilterHolder();
combined_filter = combineFilters(prev_filter, std::move(combined_filter));
}
result.setFilter(combined_filter);
/// If there is a WHERE, we filter in there, and only optimize IO and shrink columns here
if (!last_reader_in_chain)
result.optimize(merge_tree_reader->canReadIncompleteGranules(), true);
/// If we read nothing or filter gets optimized to nothing
if (result.totalRowsPerGranule() == 0)
result.setFilterConstFalse();
/// If we need to filter in PREWHERE
else if (prewhere_info->need_filter || result.need_filter)
{
/// If there is a filter and without optimized
if (result.getFilter() && last_reader_in_chain)
{
const auto * result_filter = result.getFilter();
/// optimize is not called, need to check const 1 and const 0
size_t bytes_in_filter = result.countBytesInResultFilter(result_filter->getData());
if (bytes_in_filter == 0)
result.setFilterConstFalse();
else if (bytes_in_filter == result.num_rows)
result.setFilterConstTrue();
}
/// If there is still a filter, do the filtering now
if (result.getFilter())
{
/// filter might be shrunk while columns not
const auto * result_filter = result.getFilterOriginal();
filterColumns(result.columns, current_step_filter);
result.need_filter = true;
bool has_column = false;
for (auto & column : result.columns)
{
if (column)
{
has_column = true;
result.num_rows = column->size();
break;
}
}
/// There is only one filter column. Record the actual number
if (!has_column)
result.num_rows = result.countBytesInResultFilter(result_filter->getData());
}
/// Check if the PREWHERE column is needed
if (!result.columns.empty())
{
if (prewhere_info->remove_column)
result.columns.erase(result.columns.begin() + prewhere_column_pos);
else
result.columns[prewhere_column_pos] =
getSampleBlock().getByName(prewhere_info->column_name).type->
createColumnConst(result.num_rows, 1u)->convertToFullColumnIfConst();
}
}
/// Filter in WHERE instead
else
{
if (prewhere_info->remove_column)
result.columns.erase(result.columns.begin() + prewhere_column_pos);
else
{
auto type = getSampleBlock().getByName(prewhere_info->column_name).type;
ColumnWithTypeAndName col(result.getFilterHolder()->convertToFullColumnIfConst(), std::make_shared<DataTypeUInt8>(), "");
result.columns[prewhere_column_pos] = castColumn(col, type);
result.clearFilter(); // Acting as a flag to not filter in PREWHERE
}
}
}
std::string PrewhereExprInfo::dump() const
{
WriteBufferFromOwnString s;
for (size_t i = 0; i < steps.size(); ++i)
{
s << "STEP " << i << ":\n"
<< " ACTIONS: " << (steps[i].actions ? steps[i].actions->dumpActions() : "nullptr") << "\n"
<< " COLUMN: " << steps[i].column_name << "\n"
<< " REMOVE_COLUMN: " << steps[i].remove_column << "\n"
<< " NEED_FILTER: " << steps[i].need_filter << "\n";
}
return s.str();
}
}
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